(intended for variable flow applications) · 2011. 9. 16. · model gwh 2400 es ng and gwh 2400 es...

MODEL GWH 2400 ES NG and GWH 2400 ES LP - INDOOR MODELTemperature Modulated with Electronic IgnitionSuitable for heating potable water onlyNot approved for space heating purposes(Intended for variable flow applications)

GWH 2400 ES NG - Natural GasGWH 2400 ES LP - Liquefied Petroleum (LP) Gas

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Warning: If the information in this manual is notfollowed exactly, a fire or explosion may resultcausing property damage, personal injury or death.Do not store or use gasoline or other flammablevapor and liquids in the vicinity of this or any otherappliance.

Improper installation, adjustment, alteration,service or maintenance can cause injury orproperty damage. Refer to this manual. Forassistance or additional information consult aqualified installer, service agency or the gassupplier.In the Commonwealth of Massachusetts thisproduct must be installed by a licensed plumber orgas fitter.

Upon completion of the installation, theseinstructions should be handed to the user of theappliance for future reference.

What to do if you smell gas

• Close gas valve. Open windows.

• Do not try to light any appliance.

• Do not touch any electrical switch; do not use anyphone in your building.

• If you cannot reach your gas supplier, call the firedepartment.

• Immediately call your gas supplier from a neighbor’sphone. Follow the gas supplier’s instructions

• Installation and service must be performed by aqualified installer, service agency or the gas supplier.

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Index

Index

1 Warning 3

2 Appliance details 42.1 Features 42.2 GWH 2400 ES Specifications

(Technical data) 42.3 Unpacking the GWH 2400 ES heater 52.4 General rules to follow for safe operation 62.5 Dimensions and Minimum installation

clearances 7

3 Installation instructions 83.1 Tools required for installation 83.2 Introduction 83.3 Venting 83.4 Combustion air requirements 153.5 Proper location for installing your heater 163.6 Heater placement and clearances 163.7 Mounting installation 163.8 Gas piping & connections 173.9 Water connections 203.10 Water quality 203.11 Recirculation application 213.12 Measuring gas pressure 21

4 Electrical connections 234.1 Electrical power supply 234.2 Position of the fuses in control unit 23

5 Operation instructions 245.1 LCD Display functions 245.2 For your safety read before operating

your water heater 255.3 Power 255.4 Temperature selection 255.5 Use of optional remote control accessory

(part no. TSTAT2) 265.6 Operation 265.7 Reset button 265.8 Program button 265.9 Locked condition 26

6 Maintenance and service 276.1 Annual maintenance 276.2 Winterizing for seasonal use 276.3 Mineral scale build-up 286.4 Adjusting CO2 (carbon dioxide) 286.5 Program values 316.6 Control board diagnostics 326.7 Fan speed adjustment 33

7 Troubleshooting 357.1 Introduction 357.2 Burner do not ignite when hot water

is turned ON 357.3 Water is too hot 357.4 Water is not hot enough 357.5 Low water flow/pressure 367.6 Hot water temperature fluctuates at tap 367.7 Noisy burner/heater during operation 36

8 Problem solving 388.1 Error code diagnostics 38

9 Electrical diagram 42

10 Sensor resistance charts 43

11 GWH 2400 ES Functional scheme 45

12 Interior components diagram and parts list 46

12.1 Interior components 4612.2 Components diagram 48

13 Protecting the environment 54

14 Limited Warranty 55

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Warning

3

1 Warning

For your safety

Do not store or use gasoline or other flammable,combustible or corrosive vapors and liquids in thevicinity of this or any other appliance.

FCC:This device complies with Part 15 of the FCC rules.Operation is subject to the following two conditions: (1)This device may not cause harmful interference, and (2)this device must accept any interference received,including interference that may cause undesiredoperation.

Fig. 1

Warning: Carefully plan where youinstall the heater. Correct combustionair supply and flue pipe installation arevery important. If a gas appliance is notinstalled correctly, fatal accidents canresult, such as carbon monoxidepoisoning or fire.

Warning: Exhaust gas must be ventedto outside using stainless steel ventmaterial suitable for category III ventsystems and temperatures up to 480°F.Vent piping must be sealed gas-tight toprevent possibility of flue gas spillage,carbon monoxide emissions and risk offire, resulting in severe personal injuryor death. Approved vent terminatorsmust be used when penetrating to theoutside.

Warning: Place the heater in a locationwhere water leaks will do NO DAMAGEto adjacent areas or lower floors.

Warning: Field wiring connections andelectrical grounding must comply withlocal codes, or in the absence of localcodes, with the latest edition of theNational Electric Code, ANSI/NFPA 70,or in Canada, all electrical wiring mustcomply with the local codes and theCanadian Electrical Code, CSA C22.1Part 1.

Warning: Shock hazard: line voltage ispresent. Before servicing the waterheater, unplug power supply cord fromoutlet. Failure to do so could result insevere personal injury or death.

Warning: The heater must bedisconnected from the gas supplypiping system during any pressuretesting of that system at test pressuresequal to or more than 0.5 psig.

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Appliance details

2 Appliance details

2.1 Features

Parts

• Key Pad interface control

• High power pre-mix compact burner with low NOxemissions

• Modulating Gas Valve with constant gas:air ratiocontrol

• Modulating water valve for improved comfort andtemperature control.

High quality materials for long working life

• Copper heat exchanger

• High efficiency Ceramat Burner

• Compact space saver: mounts on a wall with asupplied bracket.

Features

• Real-time diagnostics for troubleshooting/informational purposes

• LCD Display with backlight

• On/Off and Temperature control switches

• Reset button

• Program button (Selectable temperature default)

• Failure codes for easy diagnostics and repair

• Easily removable one-piece cover

• Built in freeze prevention.

Note: Freeze prevention is not intended to protectplumbing outside the appliance or to keep theappliance from freezing for long periods.

Accessories (Bosch part #)

• Optional wireless remote control accessory tooperate with the appliance (TSTAT2)

• Cascading kit (TLINK)

• Outdoor kit (AQOK).

2.2 GWH 2400 ES Specifications (Technical data)

Approved in US/Canada

Capacity

Maximum flow rate: 6.4 GPM (24 l/min) at a 45°F(25°C) rise.

Maximum output

147,000 Btu/h (43.0 kW)

Maximum input

175,000 Btu/h (51.2 kW)

Efficiency in %

Thermal efficiency > 82%

Min. Input

19,900 Btu/h (5.8 kW)

Temperature Control

Selection range: 100°F (38°C) - 140°F (60°C)

Default temperature: 122°F (50°C)

Stability: +/- 2°F (+/- 1°C)

Gas Requirement

Gas connection (inches) - ¾”

Inlet gas pressure under operation (with a high hotwater flow rate)*

• Propane: 9” - 14” water column

• Natural Gas: 4” - 14” water column.

* To measure gas pressure, see Measuring GasPressure, chapter 3.12.

Water

• Hot water connection (inches) - ¾”

• Cold water connection (inches) - ¾”

• Water valve material: Polymer (PPS) (PolypropyleneSulfid)

• Minimum water flow: 0.65 gallon/minute (2,5 l/m).Note: Activation varies with inlet water temperaturesfrom 0.65 - 1.6 gallon/minute.

• Minimum recommended water pressure: 30 PSI(2.07 bar)

• Minimum recommended well pressure: 40 PSI (2.75 bar), see chapter 3.9.

• Connections:– Bottom of heater

Combustion

• NOx ≤ 55 ppm

• CO ≤ 250 ppm

• CO2 level set from factory, see chapter 6.4.

Dimensions

• Depth (in): 11¼” (286 mm)

• Width (in): 17 7/8” (452 mm)

• Height (in): 30½” (775 mm)

• Weight: 67 pounds (30,5 kg).

Gas types

Natural Gas.LP Gas.Converting the gas type can only be done by a certifiedgas technician with a calibrated CO2 analyzer.

iBOSCH is constantly improving itsproducts, therefore specifications aresubject to change without prior notice.

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Appliance details

5

Call Bosch Water Heating through BBT North Americafor conversion instructions.

Voltage

120 V AC (60 Hz) nominal

Amperage

Idle - 40 mAOperation - ≤ 2.5 A

Noise

45 - 65 db (A)

Safety devices

• Flame failure device (ionization flame rod sensor)

• Pressure relief valve (supplied with heater)

• Over heat prevention (temperature limiter)

• Inlet temperature sensor

• Outlet temperature sensor

• Backflow temperature sensor.

Water protection

IP X4 (protection against water drops)

2.3 Unpacking the GWH 2400 ES heater

Before installing the unit, be certain you have the correct heater for your type of Gas: Propane or Natural Gas. Identification labels are found on the shipping box, and on the rating plate which is located on the right side panel of the cover.

Fig. 2 Rating plateA Serial numberB Type of gas

The box includes:

• GWH 2400 ES

• Pressure relief valve (150 psi / 200,000 Btu rating)

• Bracket for wall hanging the heater

• Exhaust vent adaptor (with 4 screws and gasketprovided)

• Combustion air inlet adaptor (with 3 screws and gas-ket provided)

• Installation manual (manual can be downloaded atwww.boschhotwater.com)

• Product registration card

• Energy Guide label.

Please complete and return the enclosed productregistration card.

The GWH 2400 ES is not approved or designedfor:

• Manufactured (mobile) homes, boats or any mobileinstallation (modular homes are acceptable forinstallation)

• Use above 4500ft A.S.L. altitude

• Outdoor installation without installation of Outdoor kit (AQOK)

• Space heating purposes

• Preheated inlet water supply.

iIf appliance is installed at elevationsbetween 2000ft and 4500ft, acombustion gas analyzer is required forproper calibration of appliance. (see page22).

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Appliance details

To remove front cover

B Loosen the two Philips head screws located onbottom rear of cover (see Fig. 3).

Fig. 3 Loosen the two screws

B Lift front cover panel upward and remove.

Fig. 4 Removing the front cover

To remove combustion cover (service only)

B Open the four clips and remove the combustioncover see Fig. 5.

Fig. 5 Remove the combustion cover

2.4 General rules to follow for safe operation

B 1. You must follow these instructions when you installyour heater. In the United States: The installation mustconform with local codes or, in the absence of localcodes, the National Fuel Gas Code ANSI Z223.1/NFPA 54.In Canada: The Installation must conform with CGAB149.(1,2) INSTALLATION CODES and /or localinstallation codes.

B 2. Carefully plan where you install the heater. Correctcombustion air supply and vent pipe installation arevery important. If not installed correctly, fatalaccidents can occur, such as carbon monoxidepoisoning or fire.

B 3. When the unit is installed indoors and ROOMSEALED (twin pipe) it is permitted to be located inbathrooms, bedrooms and occupied rooms that arenormally kept closed. See chapter 3.3 (page 8). If theunit will be installed indoors and use indoorcombustion air, the place where you install the heatermust have enough ventilation. The National FuelGas Code does not allow UNSEALED gas firedwater heater installations in bathrooms,bedrooms or any occupied rooms normallykept closed. See chapter 3.5 (page 16) and 3.4(page 15).

B 4. You must vent your heater. See chapter 3.3 onVENTING.

B 5. The appliance and its gas connection must be leaktested before placing the appliance in operation.The appliance must be isolated from the gas supplypiping system by closing its individual manual gasshutoff valve (not supplied with heater) during anypressure testing at pressures in excess of ½ Psig (3.5kPa).

B 6. Keep water heater area clear and free fromcombustibles and flammable liquids. Do not locatethe heater over any material which might burn.

B 7. Correct gas pressure is critical for the properoperation of this heater. Gas piping must be sized toprovide the required pressure at the maximum outputof the heater, while all the other gas appliances are inoperation. Check with your local gas supplier, andsee the section on connecting the gas supply. SeeSection 3.8, page 17.

B 8. Should overheating occur or the gas supply fail toshut off, turn off the gas supply at the manual gas shutoff valve, on the gas line. Note: manual gas shutoffvalve is not supplied with the heater but must be fieldinstalled.

B 9. Do not use this appliance if any part has beenunderwater. Immediately call a qualified servicetechnician to inspect the appliance and to replace anypart of the control system and any gas control whichhas been underwater.

B 10. Failure to install heater correctly may lead tounsafe operation and void the warranty.

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Appliance details

7

2.5 Dimensions and Minimum installation clearances

Fig. 6 Dimensions1 On/Off button2 Reset button3 Program key4 Power ON or stand-by LED5 LCD display6 Up button7 Down button

Fig. 7 Minimum clearances

Note: For servicing access, a 2ft clearance to front cover is recommended.

Model GWH 2400 ES

TOP (A) 12”

FRONT (B) 1”

BACK 0”

SIDES 1”

FLOOR (C) 12”

Table 1 Minimum clearances

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Installation instructions

3 Installation instructions

3.1 Tools required for installation

• Philips head screwdriver

• Flat head screwdriver

• Adjustable wrench

• Level

• Thermometer

• Standard plumbing tools

• Manometer

• Drill

• Pipe wrench

• Adjustable pliers

• Pipe fitting tools

• Hacksaw with metal blades

• Hole saw.

3.2 Introduction

Please follow these instructions. Failure to followinstructions may result in:

B Damage or injury.

B Improper operation.

B Loss of warranty.

If you are unable to perform the tasks required to installthis heater properly, please contact a locally licensedplumber or gas technician.Common installation practice is to determine theventing/intake system layout and penetration and thenwork back to the heater.

3.3 Venting

3.3.1 Vent material and specifications

Establish vent clearances that comply with the ventmanufacturer's specifications. In all cases, follow localcodes. See Table 2.

The appliance should be located as close to the pointof vent termination as possible. The maximum ventlength is 26 feet (8 m) with one 90 degree elbow andapproved terminator. Subtract 2.5 feet from the total

Warning: Do not reduce the vent(exhaust and combustion) pipe sizesand do not common vent with any othervented appliance or stove.

Warning: Failure to vent the exhaustgases to the outside with sealedstainless steel vent pipe (AL29-4C)may result in dangerous flue gasesfilling the structure in which it isinstalled.

Warning: Do not mix vent pipe orjoining methods from differentmanufacturers.

Warning: Proper end terminal / raincap must be used. Failure to do so mayresult in damage to the appliance.This damage is not covered underthe manufacturer's warranty.

Caution: The vent system must beinstalled by a qualified installer inaccordance with these instructions. Ifimproperly installed, a hazardouscondition such as explosion or carbonmonoxide poisoning could result.Bosch Water Heating will not beresponsible for improperly installedappliances.

Diam. Min. lenght

Max. length

Material

Exhaust Vent

3 or 4 inches

3 feet 26 feet with 1 90° elbow and terminal

Sealed single wall stainless steel

(AL29-4C)

Intake Vent

3 or 4 inches

1 90° elbow

26 feet with 1 90°elbow and terminal

Sealed PVC or any other rigid

pipe

Table 2 Venting Specifications

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vent length for each additional 90° elbow used (amaximum of three 90° elbows are permitted in thetotal exhaust vent length), or subtract 1.25 feet for every45° elbow used. Horizontal sections of vent must pitchupwards towards termination ¼" for every foot ofhorizontal length, to prevent the pooling of condensate,and be supported at 4 foot intervals with overheadhangers.Exception: horizontal run between last elbowand termination must pitch down to termination1/4" per foot.Note: For horizontal terminations, venting mustterminate once it penetrates to the outside of thestructure. There must be no sections of vent pipeexposed to the outdoors.Note: Listed thimbles or collars are necessary whereventing passes through wall and ceiling partitions. If thevent system passes through combustible areas wherethe vent clearance requirements cannot be maintained,it is permissible to chase straight sections of sealed 3inch single wall vent through 4 inch (or greater) Type-Bvent. The distance to combustibles using this chasetechnique is 1 inch1). Note: Type-B vent must neverbe used as the actual exhaust vent system for theappliance, as it is not gas tight and illegal for usewith this appliance. This will create a serioushealth hazard and void the warranty.

For specific questions concerning vent material, speci-fications, usage or installation, please contact the vent manufacturer directly.

Minimum exhaust vent length

Fig. 8

Maximum exhaust vent and combustion air inletlengths

Fig. 9 Maximum vent and combustion air lenghts

Note: reduce 2.5 ft for each 90° elbow used after thefirst one, reduce 1.25 ft for each 45° elbow, see table 2,page 8.

Refer to chapter 3.3.2, page 12 for condensate drainrequirements.

Vent Safety System

The GWH 2400 ES will shut down if inadequateexhaust venting is detected or a lack of combustion airis provided to the unit; see troubleshooting section onpage 35. See error code to confirm error, correct theproblem and then reset the heater before operating.

1) in all cases, follow local codes.

3” VENTING

Z flex Protech Heat Fab

3” Horizontal Terminal

2SVSTB03 FSTB3 9390 TEE

3” Vertical terminator

2SVSRCF03 FSRC3 5300CI

Table 3 Terminator Part Numbers

Fittings or Piping Equivalent

feet m

45 degree elbow 1.25 0.38

90 degree elbow 2.5 0.76

pipe per foot 1 0.30

Table 4 Friction Loss Equivalent in piping and fittings

Company Contact info

Z-flex www.z-flex.com800-654-5600

ProTech Industries www.protechinfo.com800-766-3473

Heat-Fab www.heatfab.com800-772-0739

Table 5 Vent manufacturers

The maximum exhaust vent and combustion air inlet lengths with one elbow are ≥ 26ft.

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Recommended exhaust vent terminator position

Fig. 10

* Subject to local codes and anticipated snow level

** Other equipment that operates with a mechanical air inlet may require greater distances, reference manufacturer's instructions

NOTE: terminating exhaust vent under a deck is not permitted

Ref. Description Minimum distance

ADirectly below an opening; operable windows, doors and any non-mechanical fresh air openings

36 in (twin pipe installation)48 in (single pipe installation)

B

Below a gutter, sanitary pipework or eaves 24 in

Below a gutter, sanitary pipework or eaves, protected by metal shielding

12 in

C From any internal corner 12 in

D*Above ground or snow pack 12 in

Above a paved sidewalk 7 ft

EFrom an opposing wall or structure facing the termination 24 in

From the relief valve of a Ip gas regulator 60 in

F From a terminator facing a terminator 48 in

G Vertically between two exhaust vent terminators on the same wall 60 in

H Horizontally between two exhaust vent terminators on the same wall 36 in

I**

Horizontally and vertically from combustion air inlet of a twin pipe system 36 in

From the gravity combustion air inlet any other equipment 6 ft

J From any external corner 12 in

KHorizontally from an opening; operable windows, doors and any non-mechanical fresh air openings

12 in (twin pipe installation)48 in (single pipe installation)

LVertically from a wall, roof slope, or obstruction (venting through a flat or pitched roof)

see ABOVE THE ROOF requirements on following page

Table 6

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Venting configuration examples

Fig. 11 Horizontal side wall venting installation(combustion air piping not shown)

Important:

Note: Pitch horizontal runs down toward theheater, except horizontal run between last elbowand termination which must slope down totermination 1/4" per foot.

Note: For horizontal terminations, venting must terminate once it penetrates to the outside of the structure. There must be no sections of vent pipe exposed to the outdoors.

Fig. 12 Vertical venting installation (combustion airpiping not shown)

Fig. 13 Above the roof clearance requirements fromrain cap (combustion air piping not shown)

Fig. 14 Vertical venting installation - MasonryChimney (combustion air piping not shown)

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3.3.2 Condensate drain requirements

A condensate drain must be installed under thefollowing conditions:

• All vertical terminating vent installations

• Horizontal terminating vent installations where thetotal equivalent exhaust vent length is greater than 10feet. See table 17, page 33.

• Vent installations where any section of the exhaustvent pipe passes through an unconditioned space.

Note: Do not install condensate drain in areas where itmay freeze.

1. Install condensate drain as close to heater aspossible.2. Use 3/8" ID high temperature silicone tube toconnect to condensate drain port. Do not use copperpiping for any portion of the condensate drain.3. Form a condensate trap by means of a 3" looppartially filled with water.4. To increase the tube length, connect to end of thehigh temperature silicon tubing with vinyl tubing, PVC orCPVC pipe. Do not reduce the internal diameter at anypoint.5. Dispose of condensate according to local codes.

Fig. 15 Condensate drain installation

Room sealed installation (TWIN PIPE SYSTEM)

Installing this water heater as a room sealed (TWINPIPE SYSTEM) is the recommended method. Contactyour dealer for available vent termination kits and ventmaterials for this water heater.The exhaust and combustion air piping must ventdirectly to the outside of the structure.

Fig. 16

Combustion air pipe: ≤ 26 ft (8 m) from collarExhaust vent pipe: ≤ 26 ft (8 m) from collar

Fig. 17

3" Venting Z-flex ProTech Heat Fab

90° Condensate Drain Tee

2SVEVWCF03 FST3 & FSDF3

93PPLSTEE

Horizontal Condensate Drain

2SVEDWCF03 FSHDT3 9321

Condensate Drain Tube

2SVEDTK24 N/A 7000TUBE

Table 7 Approved Condensate Drain Part Numbers

Warning: In areas where outsidetemperatures commonly fall belowfreezing, a twin pipe venting system isrequired. Failure to do so may result incold outside air being drawn across theheat exchanger coil causing it to freezeand burst. This failure is not coveredunder the manufacturer's warranty.

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Fig. 18

Open combustion installation (SINGLE PIPE SYSTEM)

Not recommended in cold climate areas, seechapter 3.4, page 15.

Fig. 19

Connecting a one piece 90 degree elbow pipe to thecombustion air inlet adaptor is required. This willprevent debris or objects from falling into the appliance.

The exhaust vent system must vent directly to theoutside of the building and an adequate amount ofindoor combustion air must be provided for thisinstallation. See chapter 3.4.Note: reduce 2.5 ft for each 90° elbow used after the

first one, reduce 1.25 ft for each 45° elbow.A maximum of three 90-degree elbows are permitted.

Determining installation adjustment

The GWH 2400 ES comes factory set to accomodate most common venting arrangements. Determine the elbows and straight pipe you will require for exhaust and combustion air. Refer to the the table below to deter-mine if the factory setting for the fan is adequate. If your venting system is longer and exceeds the values listed in Table 8, proceed to Section 6.7, page 33 for fan speed adjustment.

Note: Maximum of three 90° elbows allowed for exhaust and three 90° elbows allowed for intake.

Warning: Approved terminators mustbe used for inlet and exhaust ventsystems to prevent rain from enteringthe appliance, failure to do so may resultin damage to the appliance. This failureis not covered under the manufacturer’swarranty.

TWIN PIPE

Exhaust

Intake One 90° elbow or Less (feet)

Two 90° elbows

Three 90° elbows

1 x 90° elbow or Less

19’ 16.5’ 14’

2 x 90° elbow 16.5’ 14’ 11.5’

3 x 90° elbow 14’ 11.5’ 9’

SINGLE PIPE

No intake piping

19’ 16.5’ 14’

Maximum combined intake and exhaust vent length without fan speed adjustment.

Table 8

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3.3.3 Vent connections

B Attach the flue gas exhaust accessory (8 705 504151) to the top of the unit (position 1) using the 4screws and gasket provided. Fully insert stainlesssteel vent pipe 1.5” minimum into the accessory andtighten the clamp (position 2).

Fig. 20

B Attach the combustion air inlet accessory (8 705504 154) to the top of the unit (position 3) using the3 screws and gasket provided, and install air intakepipe over the accessory. NOTE: The appliance hasthe option to mount the combustion air inlet acces-sory on the top right or on the top left side of theheater. The combustion air inlet that is not used mustbe kept sealed.

Fig. 21

B Ensure that exhaust vent pipe is fully inserted in collar to enable proper connection.

Attention residents of the Commonwealth of Massachusetts:

In the Commonwealth of Massachusetts the followingregulation went into effect on 12/30/2005:

(a) For all side wall horizontally vented gas fueledequipment installed in every dwelling, building orstructure used in whole or in part for residentialpurposes, including those owned or operated by theCommonwealth and where the side wall exhaust venttermination is less than seven (7) feet above finishedgrade in the area of the venting, including but not limitedto decks and porches, the following requirements shallbe satisfied:

1. INSTALLATION OF CARBON MONOXIDEDETECTORS. At the time of installation of the side wallhorizontal vented gas fueled equipment, the installingplumber or gasfitter shall observe that a hard wiredcarbon monoxide detector with an alarm and batteryback-up is installed on the floor level where the gasequipment is to be installed. In addition, the installingplumber or gasfitter shall observe that a batteryoperated or hard wired carbon monoxide detector withan alarm is installed on each additional level of thedwelling, building or structure served by the side wallhorizontal vented gas fueled equipment. It shall be theresponsibility of the property owner to secure theservices of qualified licensed professionals for theinstallation of hard wired carbon monoxide detectors.

a. In the event that the side wall horizontally vented gasfueled equipment is installed in a crawl space or an attic, the hard wired carbon monoxide detector with alarmand battery back-up may be installed on the nextadjacent floor level.

b. In the event that the requirements of this subdivisioncan not be met at the time of completion of installation,the owner shall have a period of thirty (30) days tocomply with the above requirements; provided,however, that during said thirty (30) day period, abattery operated carbon monoxide detector with analarm shall be installed.

2. APPROVED CARBON MONOXIDE DETECTORS.Each carbon monoxide detector as required inaccordance with the above provisions shall comply withNFPA 720 and be ANSI/UL 2034 listed and IAScertified.

3. SIGNAGE. A metal or plastic identification plate shallbe permanently mounted to the exterior of the buildingat a minimum height of eight (8) feet above gradedirectly in line with the exhaust vent terminal for thehorizontally vented gas fueled heating appliance orequipment. The sign shall read, in print size no less thanone half (1/2) inch in size, "GAS VENT DIRECTLYBELOW. KEEP CLEAR OF ALL OBSTRUCTIONS".

4. INSPECTION. The state or local gas inspector of theside wall horizontally vented gas fueled equipment shallnot approve the installation unless, upon inspection, theinspector observes carbon monoxide detectors and

iExhaust venting must be 3" or 4" sealedsingle wall stainless steel (AL29-4C) ventpipe.

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signage installed in accordance with the provisions of248 CMR 5.08(2)(a)1 through 4.

(b) EXEMPTIONS: The following equipment is exemptfrom 248 CMR 5.08(2)(a)1 through 4:

1. The equipment listed in Chapter 10 entitled"Equipment Not Required To Be Vented" in the mostcurrent edition of NFPA 54 as adopted by the Board;and

2. Product approved side wall horizontally vented gasfueled equipment installed in a room or structureseparate from the dwelling, building or structure used inwhole or in part for residential purposes.

(c) MANUFACTURERS REQUIREMENTS - GASEQUIPMENT VENTING SYSTEM REQUIRED. Whenthe manufacturer of Product Approved side wallhorizontally mounted gas equipment provides a ventingsystem design or venting system components with theequipment, the instructions provided by themanufacturer for the installation of the equipment andthe venting shall include:

1. Detailed instructions for the installation of the ventingsystem or the venting system components: and

2. A complete parts list for the venting system design orventing system.

(d)MANUFACTURER REQUIREMENTS - GASEQUIPMENT VENTING SYSTEM NOT PROVIDED.When the manufacturer of a product approved side wallhorizontally vented gas fueled equipment does notprovide the parts for the venting of flue gases, butidentifies "special venting systems," the followingrequirements shall be satisfied by the manufacturer:

1. The referenced "special venting system" instructionsshall be included with the appliance or equipmentinstallation instructions; and

2. The "special venting systems" shall be productapproved by the Board, and the instructions for thatsystem shall include a parts list and detailed installationinstructions.

(e) A copy of all installation instructions for all productsapproved side wall horizontally vented gas fueledequipment, all venting instructions, all parts lists forventing instructions, and/or all venting designinstructions shall remain with the appliance orequipment at the completion of the installation.

3.4 Combustion air requirements

Twin pipe

The GWH 2400 ES is designed as a sealedcombustion appliance. It is recommended that thecombustion air be provided by a dedicated 3” or 4” pipefrom the outside. The combustion air pipe may be PVCor any other rigid sealed 3” or 4" pipe. The combustionair piping must pitch down 1/4 inch per foot towardstermination to prevent rain water from entering theappliance. The combustion air inlet, whether terminatingvertically or horizontally, must be located in such amanner as to provide a minimum 3 foot clearancefrom the exhaust vent terminator. See Fig. 10Letter I, page 10.The maximum length of the combustion air inletis 26 feet with one elbow. Subtract 2.5 feet foreach additional 90° elbow and 1.25 feet for eachadditional 45° elbow. Maximum number ofelbows permitted is 3.

Single pipe

Note: This appliance requires 8750 cubic feet ofavailable combustion air, or a minimum of 1094square feet of space with an 8 foot ceiling tooperate. If the large amount of air space, whichequates to about half of most average sizedhomes, is not available, the appliance must pullair from outside (see twin pipe system above).

Although it is permissible to draw combustion air frominside the structure, it is not the manufacturer’srecommended installation method. Always install a 3inch elbow on the top of the combustion air inletadaptor to prevent foreign objects from falling into theunit.If a single pipe installation is utilized, follow guidelinesbelow for providing adequate combustion air for thewater heater as well as any other appliances that may

Warning: In areas where outsidetemperatures commonly fall belowfreezing, a twin pipe venting system isrequired. Failure to do so may result incold outside air being drawn in throughthe venting system due to a negativepressure in the house and across theheat exchanger coil causing it to freezeand burst. This failure is not coveredunder the manufacturer’s warranty.

Warning: When installed in anenvironment where corrosive chemicalsor dirty air are present the twin pipesystem is required.

Warning: Vent terminations mustprevent rain from entering thecombustion air and exhaust vent piping.

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consume air in the space. Always follow local codes ifthey are more stringent.

This Installation Manual specifies the minimum exhaustvent length (Fig. 8, page 9) and the amount ofcombustion air required for this unit. When allrequirements are followed, the unit will operate properlyand safely. However, there may still be a risk of freezingdue to negative draft if the other combustion appliancesin the building are not supplied with sufficientcombustion air. A wood stove or furnace can pull itscombustion air from the heater's vent pipe, allowing thecold incoming air to freeze the cold water in the heatexchanger. Supplying more combustion air for allcombustion appliances is the solution. A HVACspecialist should be consulted to design solutions forproviding more combustion air. Observe the followingguidelines:Installations in structures that have been tightlyconstructed (air infiltration rate of 0.40 ACH or less)must be provided with combustion air per the NationalFuel Gas Code. Consult a HVAC specialist if your airinfiltration rate is questionable.The space must have two permanent openings, onecommencing within 12 inches of the top and onecommencing within 12 inches of the bottom of theenclosure.

Each opening must have a minimum free area of onesquare inch per:

• 1000 Btu/hr if all air is taken from inside the building

• 2000 Btu/hr if all air is taken from the outside byhorizontal ducts

• 4000 Btu/hr if all air is taken from the outside bydirect openings or vertical ducts.

Or the space must be provided with one permanentopening or duct that is within 12 inches of the ceiling ofthe enclosure.

This opening must have a minimum free area of onesquare inch per:

• 3000 Btu/hr if all air is taken from the outside by adirect opening or vertical duct.

Louvers, grills and screens have a blocking effect. If theeffective free area is not known, increase the sizes ofyour openings by 300% if your louvers are wood and by43% if your louvers are metal. Refer to the National FuelGas Code for complete information.

3.5 Proper location for installing your heater

Carefully select the location of the water heater. Foryour safety and for proper heater operation, you mustprovide combustion air to the heater and a properexhaust vent system.Follow the guidelines below:

B 1. Locate the heater where venting, gas andplumbing connections are feasible and convenient.

B 2. The hot water lines should be kept short andinsulated to save energy. Centrally locating the waterheater is recommended to keep hot waterdistribution times even throughout the structure.

3.6 Heater placement and clearances

The GWH 2400 ES is approved for installation ona combustible wall (see chapter 3.7 Mountinginstallation) provided the floor covering belowthe heater is noncombustible. For installations in analcove or closet, maintain the minimum clearances tocombustible and non-combustible materials listedbelow. See also Fig. 7 and Table 1 on page 7.

Clearances from any exhaust vent pipe are dependentupon the clearance requirements of the stainless steelvent pipe manufacturer. Single wall stainless steel(AL29-4C) vent pipe (vent type rated for Category IIIappliances) must be used when exhaust venting thisappliance. See chapter 3.3 (page 8) Venting.

3.7 Mounting installation

Warning: The water in this waterheater is cold and always remains coldexcept for the times the burner is on. Inthe event of power outage inconjunction with freezing temperatures,it is recommended that the heater bedrained.See chapter 6.2, page 27 “Winterizing”for draining instructions.

Warning: Flammable materials,gasoline, pressurized containers, or anyother items or articles that are potentialfire hazards must NOT be placed on oradjacent to the heater. The appliancearea must be kept free of allcombustible materials, gasoline andother flammable vapors and liquids.

Warning: before starting installation

B Check that there are no loose ordamaged parts inside theappliance

B Confirm the gas type of the heatermatches the gas supply you will beconnecting the heater, see Fig. 2,page 5.

iFront cover should be removed (seeinstructions on page 6) in order to inspectcomponents visually.

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17

If wall is sheathed with plaster or drywall, it isrecommended that two support boards, either 1”x4” or1/2" (minimum) plywood first be attached across a pairof studs, see Fig. 22.

B Secure the wall mounting bracket provided with the heater to the wall surface. The heater must be kept level on the wall surface (see Fig. 23).

B Hang the appliance on the bracket, see Fig. 24.

Fig. 22 Distance between support boards

Fig. 23 Leveling the mounting bracket on the studs

Fig. 24 Mounting the heater

3.8 Gas piping & connections

Before connecting the gas supply, check the ratingplate on the right side of the heater to be sure that theheater is rated for the same gas to which it will beconnected.In the United States: The installation must conform withlocal codes or, in the absence of local codes, theNational Fuel Gas Code ANSI Z223.1/NFPA 54.In Canada: The Installation must conform to CSA B149INSTALLATION CODES and/or local installationcodes.

GAS CONNECTIONS

B Install a manual gas shut off valve on the gas supply line within easy reach of the appliance.

B Install a union when connecting gas supply.

Warning: Do not install this applianceon a carpeted wall. The heater must bemounted on a wall using appropriateanchoring materials.

Studs 16" (406mm) on

center

Warning: Appliance must be installed vertically.

Warning: DO NOT connect to anunregulated or high pressure propaneline or to a high pressure commercialnatural gas line.

Warning: The heater must be isolatedfrom the gas supply piping systemduring any pressure testing of thatsystem at test pressures equal to ormore than 0.5 psig. If overpressure hasoccurred, such as through impropertesting of the gas lines or malfunction ofthe supply system, the gas valve mustbe checked for safe operation.

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B The minimum internal diameter required forany appliance connector is ¾”.

B Undersized flexible appliance connectors notpermitted.

B National Fuel Gas Code requires that a sediment trap (drip leg) be installed on gas appliances not so equipped. The drip leg must be accessible and not subject to freezing conditions. Install in accordance with the recommendations of the serving gas sup-plier, see Fig. 25.

Fig. 25 Gas connection (drip leg)

Once connections are made, check for gas leaks at alljoints. Apply some gas leak detection solution to all gasfittings. Bubbles are a sign of a leak. A combustible gasdetector may also be used to detect for leaks.

GAS LINE SIZINGThe gas supply piping for a single heater should besized for a maximum draw of 199,000 BTUH. Measurethe length of gas supply line and use the tables inFig. 27, page 19 or the gas line manufacturer’s sizingtables to determine the pipe diameter necessary toaccommodate the 199,000 BTU demand of the heater.If there are more gas appliances on the line, size the gasline according to the total maximum amount of BTUinput rating for all appliances.

Note: Undersizing the gas line may result in diminishedhot water flow rate and temperature. See chapter 3.12,page 21 for the procedure to confirm gas pressure.Proper gas pressure must be confirmed at time ofinstallation.

Fig. 26

Danger: If you have a leak, shut off thegas. Tighten appropriate fittings to stopleak. Turn the gas on and check againwith a gas leak detection solution.Never test for gas leaks using a matchor flame.

Gas supply

Cap

Minimum3”

Gas pipingInlet gas particle screen(included)

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19

FOR NATURAL GASMaximum Capacity of pipe in Cubic Feet of Gas per Hour for Gas Pressure of 0.5 Psig or less and a Pressure dropof 0.3” in Water Column (0.75mbar).(Based on a 0.60 Specific Gravity Gas) Btu numbers given in thousands.

Fig. 27

Follow boxed numbers for piping just one GWH 2400 ES (example: ¾” B.I. Natural Gas pipe for 10 ft (3.0m).will handle 278,000 btu’s (81.5 kWh). For multiple appliances combine the total maximum btu input load andthen refer to applicable chart below.

* EHD = Equivalent Hydraulic Diameter. The greater thevalue of EHD, the greater the gas capacity of the tubing.

Maximum Capacity of Semi-Rigid (flexible, non

corrugated) Tubing in Thousands of BTU per Hour of

Undiluted Liquefied Petroleum Gases (at 11 inches

Water Column Inlet Pressure).

(Based on a Pressure Drop of 0.5 Inch Water Column)

* Source National Fuel Gas Code NFPA 54, ANSIZ223.1 - No Additional Allowance is necessary for anordinary number of fittings

FOR LP GASMaximum Capacity of Pipe in Thousands of BTU per Hour of Undiluted Petroleum Gases (at 11 inches Water Column InletPressure) (Based on a Pressure Drop of 0.5 Inch Water Column).

* EHD = Equivalent Hydraulic Diameter. The greater thevalue of EHD, the greater the gas capacity of the tubing.

Nominal

Iron Length of Black iron Pipe , Feet

Pipe Internal

Size, Diameter

inches inches 10 20 30 40 50 60 70 80 90 100 125 150 175 200

1/4 0.364 32 22 18 15 14 12 11 11 10 9 8 8 7 6

3/8 0.493 72 49 40 34 30 27 25 23 22 21 18 17 15 14

1/2 0.622 132 92 73 63 56 50 46 43 40 38 34 31 28 26

3/4 0.824 278 190 152 130 115 105 96 90 84 79 72 64 59 55

1 1.049 520 350 285 245 215 195 180 170 160 150 130 120 110 100

1 1/4 1.380 1050 730 590 500 440 400 370 350 320 305 275 250 225 210

1 1/2 1.610 1600 1100 890 760 670 610 560 530 490 460 410 380 350 320

2 2.067 3050 2100 1650 1450 1270 1150 1050 990 930 870 780 710 650 610

Tubesize,inches EHD*

10 20 30 40 50 60

1/2 18 EHD 82 58 47 41 37 34

3/4 23 EHD 161 116 96 83 75 68

1 30 EHD 330 231 188 162 144 131

1 1/4 37 EHD 639 456 374 325 292 267

Length of Flexible Corrugated Stainless Steel Tubing (CSST), Feet

CopperOutside Length of Tubing, FeetdiameterInch 10 20 30 40 50 60 70 80 90 100

3/8 39 26 21 19 _ _ _ _ _ _

1/2 92 62 50 41 37 35 31 29 27 26

5/8 199 131 107 90 79 72 67 62 59 55

3/4 329 216 181 145 131 121 112 104 95 90

Tubesizeinches EHD*

10 20 30 40 50 60

1/2 18 EHD 129 91 74 64 58 53

3/4 23 EHD 254 183 151 131 118 107

1 30 EHD 521 365 297 256 227 207

Length of Flexible Corrugated Stainless Steel Tubing (CSST), Feet Nominal

iron Black Iron Pipe

pipe Length of Pipe, Feet

Inches 10 20 30 40 50 60 80 100 125 150 200

1/2 291 200 160 137 122 110 94 84 74 67 58

3/4 608 418 336 287 255 231 197 175 155 140 1201 1145 787 632 541 480 434 372 330 292 265 227

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3.9 Water connections

B When facing the heater, the ¾” cold connection is onthe bottom right and the hot connection is on thebottom left. Centrally locating the water heater isrecommended to keep hot water distribution timeseven throughout the structure.

Fig. 28

B The use of unions when connecting both waterpipes to the inlet and outlet connections isrequired. This will facilitate any necessaryservicing.

B Plastic or PEX type plumbing line materials are notsuitable for connecting directly to the water heater.

B Although water piping throughout the building maybe other than copper, we recommend that copper orsuitably rated stainless steel flex line piping be usedfor the water connections for 1.5’ on either side ofthe water heater (follow local codes if morestringent).

B Never sweat any piping directly to or beneaththe water connections, as damage can occur tothe internal water valve from heating of thepipe.

B Keep water inlet and outlet pipes to no lessthan ¾" (19.05mm) diameter to allow the fullflow capacity.

B If the cold and hot connections to the heater arereversed, the heater will not function. Be certain thereare no loose particles or dirt in the piping. Blow outor flush the lines before connecting to the waterheater.

B Full port shutoff valves should be installed on boththe cold water supply and hot water outlet lines tofacilitate servicing the heater (see Fig. 29).

B For installation on a private well system with the useof a pressure tank, the lowest pressure range settingrecommended is 40-60 psi (2.75 and 4.15 bar).

3.10 Water quality

Water quality can have an impact on appliancelongevity and may not be covered under themanufacturer's warranty.For water analysis data call your local water department,or if on a well, have well water analyzed periodically. Ifwater quality exceeds one or more of the valuesspecified below, Bosch recommends installing a waterconditioner or softener.

Warning: This heater is not approvedfor preheated water applications. See chapter 3.11 for approvedrecirculating application.

HOT

COLD

Description Max. Levels

pH pH 6.5 - 8.5

TDS (total Dissolved Solids)

mg/l or ppm 500

Total hardness mg/l or ppm 100 (6 grains)

Aluminum mg/l or ppm 2.0

Chlorides mg/l or ppm 250

Copper mg/l or ppm 1.0

Iron mg/l or ppm 0.3

Manganese mg/l or ppm 0.05

Zinc mg/l or ppm 5.0

Table 9

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21

Connecting the pressure relief valve (PRV)A listed pressure relief valve supplied with the heatermust be installed at the time of installation. No valve isto be placed between the PRV and the heater. Noreducing coupling or other restriction may be installedin the discharge line. The discharge line must be aminimum of 4” above a drain and installed such that itallows complete drainage of both the PRV and the line.The discharge line must be placed where it will notcause any damage.The location of the PRV must be readily accessible forservicing or replacement, and be mounted as close tothe water heater as possible. See Fig. 29. To install thePRV, a suitable fitting connected to an extension on a“T” fitting can be sweated to the hot water line.Support all piping.

Fig. 29 Plumbing Connections (with shutoff valves)and Pressure Relief Valve

1 Water filter

3.11 Recirculation application

The following drawing is provided to outline onepossible recirculation design using the water heater inconjunction with an Ariston mini tank water heater.Recirculation directly through the tankless water heaternot allowed. This schematic is for illustration only andmust not be used for actual installation withoutappropriate engineering and technical advice from aproperly licensed professional in the locality where theinstallation is made.

Fig. 30 Recirculation application1 Full port isolation valve2 Circulator (pump)3 Check valve4 PRV5 Expansion tank

The use of a small electric mini-tank water heater (4-6gallon size) should be used for this application anddesigned so the pump will circulate the water throughthe mini-tank and the building's hot water return looponly. Timed or thermostatically controlled operation ofthe pump is commonly done. Contact Bosch WaterHeating if further information is needed.

Ariston Minitank

GWH2400 ES

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3.12 Measuring gas pressure

Confirm gas pressure upon installation.

Connecting manometer

B Shut off gas supply at installer supplied shutoff valvefor this water heater.

B Remove front cover and locate inlet gas pressuremeasuring point (see Fig. 32).

B Loosen screw inside left test point fitting (do notremove) and connect manometer tube to test point.Remove screw completely if correct size tapping isavailable.

Static Pressure Test

B Turn gas supply back on.

B Record static gas pressure reading in table 11.

Operating Pressure Test

B Press ON/OFF button to turn off the appliance.

B Press and hold "Program" (P) button and press ON/OFF button to turn appliance ON.

Fig. 31

B As soon as '188' is displayed, release "Program", button and the display should read P2.

B Press or until P1 appears.

Note: While in this mode the appliance will runconstantly at maximum power and allowmaximum water flow.

For inlet gas pressure adjustment consider thefollowing table:

B Turn on high volume of hot water flow (at least 6gpm) and heater will ignite. If heater display reverts toP2, open more hot water fixtures to allow sufficientflow. Press until P1 reappears on display.

B Operate all other gas appliances on the same gaspiping system at maximum output.

B Record lowest operating gas pressure reading intable 11.

Gas pressures lower than 4" W.C. for Natural Gas or 9"W.C. for LPG will result in insufficient degree rise to thehot water being used, reduced hot water volume,possible error code faults and must be corrected. SeeGas Connections, chapter 3.8, page 17.

Fig. 32 Gas pressure test port (left tapping)

HIGH ALTITUDE OPERATION (see chapter 6.4 page 28, for details)

Gas type NG LPG

4” WC 9” WC

Table 10 Minimum inlet gas pressure under full operation

Static Gas Pressure Reading (see Chapter 3.12)

enter here: ___________________ Date: ___________

Operating Gas Pressure Reading (see Chapter 3.12)

enter here: ___________________ Date: ___________

Table 11

Altitude above sea level

Natural Gas:

Liquid Propane:

0 - 2,000 ft(0 - 610 m)

no modification

no modification

For operation at elevations

above 2,000 ft (610 m) the equipment

ratings shall be reduced at the rate of 4% for each 1,000 ft (305 m) above

sea level

2,000 ft - 4,500 ft(610 m - 1,372 m)

CO2 adjustment with flue gas analyzer required See

section 6.4 for instructions.

Above 4,500 ft(above 1,372 m) Not approved

Table 12

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Electrical connections

23

4 Electrical connections

4.1 Electrical power supply

The GWH 2400 ES requires an electrical power supplyfrom a 120VAC / 60Hz circuit (with a dedicated outlet)and must be properly grounded.The heater is wired as shown in the wiring diagram(chapter 9, Fig. 58).

Fig. 33 Connecting power supply cord1 Power cord length: 3ft.

Note: Outlet appliance is plugged in to should be clear from possible water damage.

4.2 Position of the fuses in control unit

To check fuses, proceed as follows:

B Remove the front cover, see Fig. 4, page 6.

B Remove the three screws on front of the control unit.

Fig. 34

B Pull control unit free to access and remove the sixscrews from the back cover of the control unit, seeFig. 35, pos. 2.

B Check the fuses in the printed circuit board, see Fig.35, pos. 3.

Fig. 35 Location of fuses

B After verifying the fuses mount all parts in reverseorder.

Warning: For safety reasons,disconnect the power supply cord tothe heater before any service or testingis performed.

Warning: This heater must beelectrically grounded in accordancewith the most recent edition of theNational Electrical Code. NFPA 70. InCanada, all electrical wiring to theheater should be in accordance withlocal codes and the Canadian ElectricalCode, CSA C22.1 Part 1. Do not relyon the gas or water piping to ground themetal parts of the heater.

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Operation instructions

5 Operation instructions

Fig. 361 On/Off button2 Reset button3 Program Key4 LCD display5 Up button6 Down button7 LED - Power On indicator or Stand-by

5.1 LCD Display functions

Fig. 37 Power bar indicator

Fig. 38 Temperature indicator

Fig. 39 Error indicator

Fig. 40 Lock indicator

Fig. 41 Flame indicator

Fig. 42 Remote control

Warning: Do not use any cleaning or corrosive agent to clean the window.

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25

5.2 For your safety read before operating your water heater

A. This appliance is equipped with electronic ignition forlighting the main burner. When turning the heater on,follow these instructions exactly.B. Before operating the unit, press the On/Off button.

WHAT TO DO IF YOU SMELL GAS

B Do not try to light any appliance.

B Do not touch any electric switch; do not use anyphone in your building.

B Immediately call your gas supplier from a neighborsphone. Follow the gas supplier’s instructions.

B If you cannot reach your gas supplier, call the firedepartment.

C. Use only your hand to press the on/off control switch.Never use tools. Follow these instructions exactly. Ifcontrol switch is jammed, close the gas supply and calla qualified service technician. Attempted forceful repairmay result in a fire or explosion.D. Do not use this appliance if any part has been underwater. Immediately call a qualified service technician toinspect the appliance and to replace any part of thecontrol system and any gas control which has beenunder water.

5.3 Power

On

B To start the appliance press the On/Off button.

Fig. 43

Off

B To shut down the appliance press the On/Off buttonagain.

5.4 Temperature selection

To select output water temperature:

B Press buttons or in order to reach desiredtemperature.

Fig. 44

Setting the water temperature

The desired temperature of the hot water can beadjusted on the front control panel of the heater.The GWH 2400 ES has an electronically controlled gasvalve that modulates the burner input in response toboth varying hot water flow rates and/or changes in anyincoming and outgoing water temperatures.

Note: The water heater, running at minimum BTU, maystill achieve temperatures above the desired settemperature. Low flowing fixtures are the leading causeof this type of temperature overshoot. To combat thissymptom, clean fixtures or replace with higher flowingones.

Saving water resources:

B Make sure you close all the taps after any use. Avoidleaving the taps dripping. Repair any leaking tap.

B Define the temperature you want, in the appliance orwith the remote control. This way you have theprecise water flow needed (mixing cold water toregulate temperature will increase the water flow withconsequent waste of water).

Warning: If you do not follow theseinstructions exactly, a fire or explosionmay result causing property damage,personal injury or loss of life.

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5.5 Use of optional remote control accessory (part no. TSTAT2)

Fig. 45 Remote control

The wireless remote control accessory (Fig. 70,component 13) and the temperature selector buttonson the front of the water heater operate identically.Contact your distributor to order the remote controlaccessory. Modification of the water heaters interiorcontrol unit (Fig. 70, component 16) is required whenprogramming the remote control with this heater.

5.6 Operation

B When a hot water tap is opened, main burner ignites and LCD displays the symbol .

Fig. 46

B LCD blinks until selected temperature is reached.

5.7 Reset button

If the LCD shows the error symbol do not shut offpower or unplug the heater.See the error code on LCD and consult“Troubleshooting” section.

Fig. 47

After following instructions indicated in“Troubleshooting” section.

B press reset button to return heater to normaloperation.

Fig. 48 Reset button

If the problem persists, contact your installer.

5.8 Program button

Program button can be used on the appliance and in theremote control.

Programming “Program” functionProgramming actions are similar for both controls(appliance control pad and wireless remote control).

Fig. 49 “Program” key

Memorizing selected temperature

B Press buttons or to select temperature to bememorized.

B Hold “Program” button for 3 seconds to savetemperature.

When LCD stops blinking, temperature is saved inmemory.

Using “Program” functionIn order to select memorized temperature

B Press “Program” key.

LCD shows pre-memorized temperature, which is nowthe hot water selected temperature.

5.9 Locked condition

This condition is only valid for appliances with remotecontrols.

Fig. 50 Locked condition

Whenever LCD shows the temperature settingcannot be adjusted because the appliance is in use bya user which already selected a different temperature.Appliance will be automatically unlocked five minutesafter closing the hot water tap.

iNOTE: up to 6 remote controls can beprogrammed for one single water heater,each with a range distance of 98 ft (30 m).

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Maintenance and service

27

6 Maintenance and service

The unit should be checked once a year by a gastechnician. If repairs are needed, the repairs should bedone by a gas technician.

6.1 Annual maintenance

(To remove front cover, see page 6.)

Venting System

• Venting system - inspect inside of flue pipe for anyblockage or restriction. Observe burner flamesduring heater operation. (Vent pipe must beremoved). Inspect the combustion air inlet pipe forblockage or debris. Inspect combustion air andexhaust terminations for blockage or debris.

Combustion chamber

• Inspect burner observation window (Fig. 63, #10) forcracks or spillage of flue gases. Observe burnerflames during heater operation. Flames should besteady and blue with no signs of yellowing. Yellowburner flames are an indication of impropercombustion. Refer to Section 3.4 & 3.3 of thismanual to ensure that exhaust system andcombustion air supply meets manufacturer'sspecifications.

Inlet water filter

• Verify the inlet filter screen is clean and undamaged.The inlet water filter is located inside the cold waterinlet fitting on the right side of the appliance (SeeFig. 51, page 27). Close installer supplied cold watershutoff and loosen slotted screw on inlet fitting.Water will drain from the appliance. Removecylindrical filter inside.

Fig. 51 Water filter1 Inlet water filter2 Water filter

Descaling

• In areas where the water supply has a high mineralcontent (see Table 9, page 20), the heat exchangershould be periodically flushed with a descalingsolution. Scale build up will shorten the life of thewater heater and damage resulting from is notcovered under warranty. Refer to section 6.3 fordetailed instructions on descaling the heatexchanger.

Heat exchanger fin coils

• Inspect heat exchanger fincoil for soot build-up orblockage. To access fincoil, venting must beremoved from flue gas exhaust accessory. Withventing removed and inspect fincoil below with aflashlight. If there is evidence of soot build-up orblockage, the heat exchanger should be removed bya professsional and cleaned thoroughly. To removethe heat exchanger, consult service bulletin atwww.boschhotwater.com.

6.2 Winterizing for seasonal use

Installation instructions state that the water heater mustnot be installed in a location where it may be exposed tofreezing temperatures. If the heater must be left in aspace which is likely to experience freezingtemperatures, all water must be drained from the heater.If precautions are not taken, resulting damage will notbe covered under the warranty. NOTE: Use of agents

Warning: Always turn off the electricalpower supply, turn off the manual gasshut off valve and turn off the water shutoff valves whenever servicing.

Caution:

B Check and clean the complete waterheating system once a year.

B Carry out a maintenance overhaul ifnecessary. Immediately repair defects toavoid damage to the system.

Annual maintenance table

Every year

1. Inspect venting system X

2. Inspect heat exchanger X

3. Inspect burner X

4. Inspect condensate trap X

5. Inspect water filter X

Table 13 Annual maintenance

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such as anti-freeze is not permitted as they may causedamage to the water heater's internal components.

1. Press ON/OFF switch on the water heater to turnOFF the heater and unplug power supply cord. Thedisplay should be blank.

2. Shut off gas supply to heater.

3. Shut off the water supply to the water heater usinginstaller supplied shutoff valve.

4. Open hot water taps to drain the plumbing system. Ifwater continues to flow after 5 minutes, a plumbingcrossover is present and must be corrected beforeproceeding.

5. Open service valves (if available) or disconnect inletand outlet water pipes from the water heater. Place asmall bucket underneath the water heater to catchresidual water remaining inside the water heater.

6. Using an air compressor, blow short bursts of air(100psi max) through the outlet water connectionuntil there is no water present coming through theinlet water connection of the heater.

7. Reconnect water fittings and return heater to servicewhen danger of freezing has past.

6.3 Mineral scale build-up

Periodic descaling may be necessary in areas with highmineral content in the water. Scale buildup in the heatexchanger may result in lower flow rates, error codes ofA7 and E9 and boiling sounds (knocking and banging)in the heat exchanger.

Descaling using a pump

1. Disconnect electrical supply from the water heater.

2. Shut off the water supply to the water heater using(installer supplied) shutoff valve.

3. Open hot water taps to drain and relieve pressurefrom the plumbing system.

4. Drain water from the unit's heat exchanger bydisconnecting inlet and outlet water connectionsfrom the heater.

5. Connect a line (A) from the outlet of the circulatingpump (installer supplied) to the inlet water fitting onthe water heater (see Fig. 52).

6. Using another line (B), connect to the water outletfitting on the water heater. Route the other end of thisline into a descaling reservoir.

7. Using a 3rd line (C) from the descaling reservoir, connect to the inlet side of circulating pump. Install a filter on the end of this line in the descaling reservoir.

8. Make sure all connections are "water tight.".

9. Fill tank with descaling solution so both lines insideare submersed. We recommend straight whitevinegar. If using a commercial descalant, refer tomanufacturer's instructions on dilution with water.

10.Operate the circulating pump.

11.Make sure there are no leaks and the solution isflowing from the descaling reservoir through theheater and returning to the reservoir.

12.Run solution through the heater until the solutionreturning to the descaling reservoir comes out clear.(Changing to a fresh solution may be necessaryduring this process).

13.Disconnect all lines and drain all solution from heatexchanger. Properly discard of solution.

14.Position a container below the hot water outlet andconnect cold water supply. Open cold water supplyisolation valve and flush heat exchanger with cleanwater.

15.Shut cold water shutoff valve and reconnect hotwater supply to the water heater.

16.Reconnect electrical supply to unit, open watershutoff valves, and return the unit to service.

Fig. 52

6.4 Adjusting CO2 (carbon dioxide)

The CO2 can only be adjusted by a certified gastechnician with a calibrated CO2 analyzer.

Static Gas Pressure: “ WC

P1 Operating Pressure: “ WC

The P1 minimum operating gas pressure is 4" WC for Natural Gas and 9" WC for Propane. Do not proceed in

Caution: One factor that may affectCO2 levels is improper gas pressure.Please see Chapter 3.12 for theprocedure to measure gas pressureand record your findings below:

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29

adjusting CO2 until pressure is at or above these levels, but not to exceed 14” WC.

A. Once Gas Pressure is adequate

B Press ON/OFF button to turn off the heater.

B Remove brass flat head screw on the exhaust collaras seen in Fig. 53.

B Insert CO2 analyzer probe into the measuring port.The tip of the probe should be in the center of the fluepipe (approx 1.5" inserted). Avoid air gaps betweenprobe and measuring port as they can alter readings.

Fig. 53 Measuring port

B While holding the Program (P) button in, press theON/OFF button to turn ON the heater (see Fig. 54).As soon as ‘188’ flashes on the display, release theProgram button. The display should now read P2.Press button until “P1” appears on display.

Fig. 54

B. Measuring CO2 (combustion cover must beinstalled):

B Open all hot water taps to achieve a flow rate of atleast 6 gallons per minute. (1 tub and 2 sinks shouldbe sufficient). If heater display reverts to P2, openmore hot water fixtures to allow sufficient flow. Press‘ ’ until P1 reappears on the display.

B Record the CO2 reading in P1 below. (Analyzerreading may take several minutes to stabilize).

B Press the ‘ ’ button until P2 appears. Unit willramp down to low fire and the flow should decrease.

B Record the CO2 reading in P1 and P2 below.

P2 CO2 Reading: % CO2


C. Adjusting CO2:

Note: P1 adjustment will change the P2 reading.Confirm the P1 value BEFORE adjusting the P2 level.

1. If P1 CO2 level is off:

B Loosen yellow painted philips screw (1) and covershould rotate down (2) revealing a recessed brassslotted screw. Fig. 55.

B Turning the slotted screw counter clockwise willraise P1 CO2 levels and clockwise will lower P1CO2 levels. Adjustments to the slotted screw willalso change P2 CO2 levels.

B After bringing the P1 CO2 readings in proper range,press the button to enter the P2 mode. VerifyCO2 readings in P2 mode.

2. If P2 CO2 level is off:

B Remove yellow painted #40 Torx cover from the frontof the gas valve. (Fig. 56) A plastic #40 Torx screwwill be revealed.

B Turning the plastic #40 Torx screw counterclockwise will lower P2 CO2 levels and clockwisewill raise P2 CO2 levels.

Note: This screw adjustment is very sensitive andshould be made in small increments. It may take severalminutes for readings to stabilize.

3. Verify both P1 and P2 CO2 readings are within theranges specified in table 14. Repeat steps 1 and 2 asnecesssary until CO2 values are within the specifiedranges.4. Once CO2 values are within the specified ranges,verify the CO readings on P1 and P2 do not exceedvalues shown in table 14. If values exceed this limit,inspect vent system and fin coils (chapter 6.1, page 27)for blockage.

D. Returning to Service:

1. Return slotted screw cover to original position andtighten philips screw.2. Reinstall Torx cover.3. Remove CO2 analyzer probe and reinstall flatheadscrew with gasket in exhaust collar.4. Press ON/OFF button to turn OFF the heater andthen turn ON the heater.5. Heater is ready for normal operation.

6 720 608 78230


Final Readings



Fig. 55 Adjusting P1 CO2 level

Fig. 56 Adjusting P2 CO2 level

CO2 range (%) Max. CO level

Nat. Gas

max. input P1 6.9 % - 7.5 % < 250 ppm

min. input P2 2.3 % - 2.6 % < 55 ppm

LP Gas

max. input P1 8.1 % - 8.7 % < 250 ppm

min. input P2 2.5 % - 2.8 % < 55 ppm

* Values above are for climate controlled conditions.Inputs such as gas pressure, heating value of the gas,humidity and temperature of combustion air all impact COand CO2 values. Changes in these inputs can result indifferent CO and CO2 values on the same appliance.

Table 14 CO2 & CO target numbers

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31

6.5 Program values

This section describes details on programming theappliance. For most applications the factory defaultvalues will robust and stable operation. Only adjust thefactory settings if the installation requires changes asindicated in the appropriate section of this manual.

Refer to chapter 6.6 Control board diagnostics (page32) regarding how to access these P-modes.

Caution: Misadjusted programvalues can lead to appliancemalfunction, errors, and servicecalls.

Program Description Factory Default MIN MAX Comment

P1 Maximum Power NG:40, LP:39 21 NG:40, LP:39 see chapter 3.12, page 21.note: reducing P1 values below maximum will reduce maximum power of the appliance.

P2 Minimum Power 6 6 20 see chapter 6.7, page 33

P3 Remote Con-trols installed

_0 _0 6 see chapter 5.5, page 26

P4 Access to Diag-nostic Mode

E 0d 10f see chapter 6.6, page 32

P6 Temperature Unit

°F °F °C

Table 15 Program values, factory default settings and ranges.

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6.6 Control board diagnostics

1. Turn on/off switch on water heater to off (O) position.

2. Press and hold the program ( ) button whileturning the on/off switch to the on (I) position. Thedisplay will cycle through a startup procedureincluding the software version.

3. Release the ' ' button when '188' appears on thedisplay. The display should read 'P2' when theprogram button is released. If not, repeat process.

4. Press and release the ' ' button on the controlpanel until the display reads 'P4'. You are now in thediagnostic mode of the control board.

5. When the display reads 'P4', press and release the' ' button once again and the display should read'E'.

6. Use the ' ' and ' ' button on the control boardto cycle through different diagnostic modesavailable.

7. Once in the selected diagnostic mode of yourchoice, press and release the ' ' button to displaythe diagnostic information.

EXAMPLE: to read the flow rate in gallons per minutewhile the unit is flowing water, cycle to the '3d' modeand press the ' ' button. A reading of 25 on thedisplay would indicate the heater is reading a flow rateof 2.5 gallons/minute.

8. Once the information is obtained, press the ' 'button again to return to the diagnostic mode menuand scroll to addition diagnostic information.

9. To exit the diagnostic mode of the heater, use the' ' or ' ' button until the display reads 'E'.

10.Press the ' ' button once again and the displayshould read P4.

11.Turn the on/off switch off (O) and back on (I) againto return heater to normal function.

Diagnostic menu

E Entry/Exit into sub-modes

0d Set-point temperature (°F)

1d Inlet water temperature (°F)

2d Outlet water temperature (°F)

3d Water flow (gallons/min)

4d Gas type (LP or NG)

5d Fan speed (Hz)

6d Burner power (%)

7d Maximum power (kW)

8d Back flow temperature (°C)

9d Flue gas temperature (°F)1)

1) Available only on model GWH C800 ES

1F Most recent error/failure

2F 2nd most recent error

3F 3rd most recent error

4F 4th most recent error







Table 16

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33

6.7 Fan speed adjustment

Installation adjustment: Flue pipe length setting for minimum power - P2.

After installing the GWH 2400 ES, the minimum powerfan speed must be selected to compensate for variationin vent pipe length.

Total vent length calculation

B Determine the total length of all straight sections ofvent pipe and enter in table 17, line 1.

B Count the number of 90° elbows used and enter thatvalue in line 2. (Do not count end terminal and firstelbow after the appliance).

B Count the number of 45° elbows used and enter thatvalue in line 3.

B Repeat steps 1 through 3 for air intake pipe and enterthose values in the intake section of table 17.

B Add line 4 from Exhaust to line 4 of Intake and enterresult in line 5.This is the total equivalent vent length.

Example

Exhaust

• 7 - 3' straight sections

• 1 - 1' straight sectionTotal length 22'

• 2 - 90° elbow.

Intake

• 5 - 3' straight sectionsTotal length 15'

• 2 - 90° elbows.

Example

Note: Do not count 1st elbow and terminators

Exhaust

1 Straight section length __ x 1 = ____

2 90° elbows (qty) __ x 2.5 = ____

3 45° elbows (qty) __ x 1.25 = ____

4 Total: ____

Intake

1 Straight section length __ x 1 = ____

2 90° elbows (qty) __ x 2.5 = ____

3 45° elbows (qty) __ x 1.25 = ____

4 Total: ____

5 Total equivalent vent length = ____

Table 17Determining vent length combination (see example in Table 18)

Exhaust

Straight section length (feet)

22 x 1 = 22

90° elbows (qty) 1 x 2.5 = 2.5

45° elbows (qty) 0 x 1.25 = 0

Total: 24.5

Intake

Straight section length (feet)

15 x 1 = 15

90° elbows (qty) 1 x 2.5 = 2.5

45° elbows (qty) 0 x 1.25 = 0

Total: 17.5

Total equivalent vent length = 42

Table 18Determining vent length combination example

iTotal maximum length not to exceed 52ft.

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To select fan speed:

B Press ON/OFF button into OFF.

B Press and hold "Program" button and pressON/OFF button to turn appliance ON.

Fig. 57

B As soon as '188' is displayed, release "Program"button , and the display should read P2.

B Press or to choose the fan speed suitablewith your installation, see Table 19.

B Press and hold (± 5 sec.) “Program” button untilthe display flashes, then the selected value ismemorized.

Mode Pipe Length1)

1) Full equivalent length (inlet+outlet+fittings). Do not count terminals and first elbow used on intake and exhaust.

Fan speed

“P2”

for 3 ft up to 19 ft 6

for 20 ft until 46 ft 7

for 47 ft until 52 ft 8

Table 19Fan speed adjustment

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Troubleshooting

35

7 Troubleshooting

7.1 Introduction

Many of the questions customers ask regardingoperation of this unit can be answered by following thetroubleshooting steps as outlined below. Visit our website at www.boschhotwater.com for more detailedtroubleshooting and service bulletins. For best results,perform each step before proceeding to the next. Thesuggested solutions may require that the cover be takenoff. (See Page 6. Fig. 3).

7.2 Burner do not ignite when hot water is turned ON

1. If the display is blank, verify power to outlet.(120VAC/60Hz properly grounded circuit required).Verify that the heater ON/OFF button is turned ON.

2. Verify the fuses in the control board are good. SeeSection 4.2, page 23 of the installation manual forfuse locations.

3. Make sure cold water inlet connection is plumbed tothe right side of heater when facing unit. See Fig. 28,page 20.

4. A minimum of 0.65 gallons per minute (GPM) (2.5 l/m) is required to activate the heater. A quartcontainer should fill in 25 seconds or less to activateheater. In areas of warm inlet water temperatures, theheater may increase activation rate to as high as 1.6gallons per minute (GPM) to prevent overshooting ofset temperature.

5. Clean inlet filter screen per chapter 6.2, page 27.

6. Inspect the water path for obstructions. Make sure allshowerheads, faucet aerators and whole housefilters are clear of debris.

7. The heater activates when the water flow through theunit is at or above the required minimum of 0.65GPM (2.5 l/m). A crossover in the plumbing createsback pressure on the water flowing through theheater. Therefore, a higher flow rate than normal isneeded to force the heater to activate. To check fora plumbing crossover, shut off the cold water supplyto the water heater. Then open all of the hot watertaps served by the heater. Wait 10 minutes andcheck for water flow at taps. There should be nowater flowing. Any continuous flow of water, small orlarge, indicates a crossover is present and must becorrected. Consult a professional plumber for help incorrecting a crossover. Failing single lever faucets

and mixing valves are common causes of plumbingcrossovers.

8. With the ON/OFF switch turned to OFF (O) positionand the power supply cord unplugged, remove theunit's front cover (See Page 6. Fig 3). Check wireconnections between the water valve, control unitand electrode set. See chapter 12.1, page 46 forlocation of these parts.

7.3 Water is too hot

1. Selected temperature on the unit is set too high. Tolower output temperature, see chapter 5.4, page 25.



4. Confirm the heater's gas type coincides with the typeof gas being supplied. See Fig. 2, page 5 for locationof rating plate.

5. Avoid restrictive outlets. Clean all showerheads andfaucet aerators. It may be necessary to upgrade tohigher flow rate shower heads if allowable by localcode.

6. In areas where the water has a high mineral content,periodic descaling may necessary. See chapter 6.3,page 28 for directions.

7. Ensure the outlet temperature sensor is makingcontact and firmly mounted on the hot water pipe.

7.4 Water is not hot enough

1. Selected temperature on the unit is too low. To raiseoutput temperature, see chapter 5.4, page 25.

2. Clean inlet filter screen. See chapter 6.1, page 27.


4. Confirm the heater's gas type coincides with the typeof gas being supplied. See Fig. 2, page 5 for locationof rating plate.

5. Check inlet gas particle screen for blockage at gasinlet connection on bottom of unit.

6. Verify gas pressure is in accordance withspecifications in chapter 3.12, page 21. A gaspressure reading is needed to proceed further.Contact your original installer or a local certified gastechnician to obtain this reading.

7. Cold water is mixing into the hot water lines(plumbing crossover). A plumbing crossover canunintentionally mix cold water with the hot waterleaving the heater. The end result is a cooler watertemperature than desired. To check for a plumbingcrossover, shut off the cold water supply to the waterheater. Then open all of the hot water taps served by

Warning: If you are unable to performthe tasks listed below, or needadditional assistance please contactyour original installer or licensed gastechnician.

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Troubleshooting

the heater. Wait 10 minutes and check all taps forwater flow. There should be no water flowing. Anycontinuous flow of water, small or large, indicates acrossover and must be corrected. Consult aprofessional plumber for help in correcting acrossover. Failing single lever faucets and mixingvalves are common causes of plumbing crossovers.

8. Ensure the outlet temperature sensor is makingcontact and firmly mounted on the hot water pipe.

7.5 Low water flow/pressure

1. Too many hot water applications are being usedsimultaneously or too much flow is demanded. Thewater heater will effectively support two 2.0-2.5GPM shower heads simultaneously or multiple sinkapplications. Greater draws will result in a waterpressure drop and reduced flow at taps.

2. Ensure that gas pressure is in accordance withspecifications in chapter 3.12, page 21. A gaspressure reading is needed to proceed further.Contact your original installer or a local certified gastechnician to obtain this reading. If gas pressure isinadequate, the water heater will close its motorizedwater valve, reducing the hot water flow rate in anattempt to reach the selected output temperature.

3. If selected temperature on the unit is set too high forthe demanded flow rate, the water heater will closeits motorized water valve, reducing the hot water flowrate in an attempt to reach the selected outputtemperature. Lowering the selected temperature willallow the motorized water valve to open up forincreased water flow rate.



7.6 Hot water temperature fluctuatesat tap

1. Hot water is very hot out of the tap, requiring mixingof cold water in order to attain a useable hot watertemperature. The addition of too much cold water willoverpower the hot water flow from the tankless waterheater.This slows the flow within the tankless water heater,decreasing it below activation point, which shuts offthe burners. The end result is nothing but cold watercoming out of the outlet. Consult www.boschhotwater.com for a detailedservice bulletin on overcoming temperaturefluctuations.

2. Unbalanced pressure in water lines. Any restriction inthe water heater, such as a clogged inlet filter screen,can result in unequal pressures between the coldand hot water lines. In such cases, when mixing in thehigher pressure cold water at the tap, the lower

pressure hot water can be overpowered. This willshut down the burners because the hot water flowrate fell below the minimum flow rate required foractivation. Verify inlet filter screen is clean and clearof debris. See chapter 6.1, page 27 for inlet filtercleaning instructions.

3. Heater deactivated by temperature balancing valves.If the outlet water temperature is set too high, theheater can produce temperatures that are too hot. Atemperature balance shower valve will automaticallymix in cold water to reduce the hot watertemperature. In the event of any temperatureinstability at a fixture using a temperature balancingvalve, refer to the valve manufacturer for instructionson internal adjustment setting. An adjustment shouldbe made to minimize the amount of cold water thevalve is adding. Additionally, the temperature settingon the heater can be lowered to prevent thetemperature balance valve from mixing in too muchcold water.

4. Inlet water pressure is erratic due to fluctuatingsupply water pressure. For installation on a privatewell system with the use of a pressure tank, thelowest pressure range setting recommended is 40-60 psi (2.75 - 4.15 bar). Consult your installer orlocal plumber for effective ways to maintain constantwater pressure to the water heater when on a wellsystem.

7.7 Noisy burner/heater during operation

1. Sealed combustion leak. Make sure combustioncover is securely fastened. Ensure the exhaust ventadaptor is properly sealed with supplied gasket.Leaky seals create improper combustion resulting innoise.

2. Improper venting. Venting that is unsealed, the wrongmaterial, too big in diameter or too long in run willresult in unstable burner flames and noise. Ensureventing is proper and in accordance withspecifications in chapter 3.3, page 8.

3. Lack of adequate combustion air. Drawingcombustion air from a room area of inadequate sizewill result in unstable burner flames and noise.Improper use of piping for combustion air will resultin unstable burner flames and noise. Ensureadequate combustion air is provided to the unit inaccordance with specifications in Section 3.4, page15, Combustion Air Requirements.

4. Cross contamination. Ensure that intake and exhaustterminations maintain minimum required clearancesstated in the manual. Cross contamination betweenintake and exhaust may cause unstable burner flamesand noise.

5. Lack of adequate gas pressure. Inadequate gaspressure will cause the fuel-to-air mixture (CO2) to be

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Troubleshooting

37

out of adjustment. This will result in unstable burnerflames and noise. Ensure gas pressure is inaccordance with specifications in section 3.12, page21 Measuring Gas Pressure. A gas pressure readingis needed to proceed further. Contact your originalinstaller or a local certified gas technician to obtainthis reading.

6. Verify proper CO2 readings per chapter 6.4, page28. CO2 adjustments must be done by a certifiedgas technician with a calibrated combustion gasanalyzer.

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Problem solving

8 Problem solving

8.1 Error code diagnostics

iTo remove error code from the display, press the reset button.

Display Cause Solution

Fault in the flue gas limiter. 1. Check continuity of the flue gas limiter (see Fig. 63, page 46).Go to steps two and three to determine air box temperaturesensor fault and replace it.2. Check for flue gas leakage around the top and bottom seals ofheat exchanger as well as the viewing window.3. Check that venting is within specifications (see Section 3.3).Long vent lengths, venting with more than three elbows, blockedvent or combination venting may cause this failure.4. Check that flue gas limiter connector and spade connectionsare secure.5. Unplug heater and check the two main plug connections insidethe control board.

Jumper connection is not correct. 1. Check jumper connection on connector at upper right hand corner of heat exchanger.

Backflow temperature sensordefect - happens if sensor isdisconnected or short circuit.

1. Check backflow temperature sensor connection and resistance.See Fig. 61, page 44 and Fig. 63, page 46.2. Replace backflow temperature sensor.

Outlet temperature sensor fault(Temperature below freezing orabove 210°F).

1. Check red wire connections at hot water temperature sensor.Clean terminals with an eraser. If badly corroded, replace sensorand wire harness. See Fig. 63, page 46.2. Sensor may trip if water temperature drops below freezing toprotect heater from freezing conditions. Any damage due tofreezing conditions is not covered under warranty.3. Clean inlet filter screen and clear any debris out of showerheads, faucet aerators and whole house filters.4. In areas where water has a high mineral content, periodicdescaling may be necessary.

Table 20* By installer or service technician only.

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Problem solving

39

(Flashing) Outlet temperature sensor notsensing expected outputtemperature.

1. Check that the sensor is firmly attached to the hot water pipe(see Fig. 69, page 52).2. Clean inlet filter screen and clear any debris out of showerheads, faucet aerators and whole house filters.3. Check venting specifications are met. Long vent lengths,venting with more than three elbows, blocked vent or combinationventing may cause this failure.4. Check gas pressure. Low gas pressure may prevent the heaterfrom reaching desired output temperature.5. Check supply voltage. It must be 120VAC and properlygrounded.6. Possible defective control unit call Bosch Water Heating forfurther instructions.7. Ensure that outlet temperature sensor is not placed on anybends in the hot water pipe or misreading may occur.

Primary fan rotation too low onstartup.

1. Disconnect power supply cord and check wire connections onback side of primary fan and the two connectors on the controlboard (see Fig. 70, page 53).2. Check supply voltage. It must be 120VAC and properlygrounded.3. Check venting specifications are met. Long vent lengths,venting with more than three elbows, blocked vent or combinationventing may cause this failure.4. Check gas pressure. Low gas pressure may cause the fan tochange its speed to meet desired temperature.5. Possible defective control unit call Bosch Water Heating forfurther instructions.

Primary fan rotation too low onoperation.

1. Disconnect power supply cord and check wire connections onback side of primary fan and the two connectors on the controlboard (see Fig. 70, page 53).2. Check supply voltage. It must be 120VAC and properlygrounded.3. Check venting specifications are met. Long vent lengths,venting with more than three elbows, blocked vent or combinationventing may cause this failure.4. Ensure intake and exhaust terminations maintain the requiredminimum clearances stated in the manual. Cross contaminationbetween intake and exhaust may cause the fan to alter itsrotational speed.5. Check gas pressure. Low gas pressure may cause the fan tochange its speed to meet desired temperature.6. Possible defective control unit call Bosch Water Heating forfurther instructions.

No rotational speed sensor signalfrom primary fan.

1. Disconnect power supply cord and check wire connections onback side of primary fan and the two connectors on the controlboard (see Fig. 70, page 53).2. Check supply voltage. It must be 120VAC and properlygrounded.3. Possible defective component in fan or defective control unitcall Bosch Water Heating for further instructions.

(Flashing) Water flow signal over specifiedmaximum value.Water flow > 10 gallon/min.

1. Disconnect power supply cord and check wire connections onwater valve and the two connectors on the control board (seeFig. 70, page 53).2. Excessive water pressure and flow. Ensure water pressure isless than 150psi and flow rate is below 10 gallons per minute.



6 720 608 78240

Problem solving

Internal hardware/software failure. 1. Disconnect power supply cord and check the two wire andground connections on control board as well as ground connectionon heater chassis.2. Pushing the wrong combination of buttons on the control unitcan create confusion among the microprocessors inside. In thiscase, the error code should not happen more than once or twice.Turn off the water heater. Turn water heater back on and tryresetting error code. Use the reset button ( ) to reset any errorcodes.3. Possible defective control unit. Call Bosch Water Heating forfurther instructions.

Over-temperature detected byoutlet temperature sensor on hotwater pipe.Temperature > 185°F

1. Check that the sensor is firmly attached to the vertical section ofthe hot water pipe (see Fig. 69, page 52).2. Check red wire connections at outlet temperature sensor.Clean terminals with an eraser. If badly corroded, replace sensorand wire harness. Check sensor resistance (see Fig. 59, page43.3. Clean inlet filter screen per chapter 6.2, page 27 and clear anydebris out of shower heads, faucet aerators and whole housefilters.4. In areas where water has a high mineral content, periodicdescaling may be necessary. See chapter 6.3, page 27 fordirections.

Cold water temperature sensorfault.

1. Check connector on wires coming from top of watervalve for asecure connection. See Fig. 63, page 46.2. Sensor may trip if water temperature drops below freezing toprotect heater from freezing conditions Any damage due tofreezing conditions is not covered under warranty.

Backflow temperature sensor over309°F.The appliance will close the burnerand lock.

1. Check combustion air and backflow vent piping for blockage.2. Check if secondary fan connections are disconnected.3. Check venting specifications are met. Long vent lengths,venting with more than three elbows, blocked vent or combinationventing may cause this failure.4. Check sensor resistance (see Fig. 61, page 44).

Overheat sensor (ECO) opencircuit (should reset when coolertemperatures are detected).

1. Disconnect power supply cord and check wire connections onoverheat sensor (top right of heat exchanger) and the twoconnectors on the control board. See Fig. 63, page 46.2. Check white wire connections at overheat sensor. Cleanterminals with an eraser. If badly corroded, replace sensor andwire harness.3. Check venting specifications are met. Long vent lengths,venting with more than three elbows, blocked vent or combinationventing may cause this failure.4. Clean inlet filter screen and clear any debris out of showerheads, faucet aerators and whole house filters.5. In areas where water has a high mineral content, periodicdescaling may necessary, see chapter 6.3.6. Unplug power supply cord to the water heater. Open a hotwater tap for several minutes to allow cold water to pass throughheat exchanger. Close hot water tap and disconnect lead wires tooverheat sensor. Using a multimeter, check continuity throughoverheat sensor contacts. Replace sensor if open.



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Problem solving

41

No flame ionization detected withwater flow.

1. Verify that all manual gas shut off valves are open.2. Check gas type, see Fig. 2, page 5.3. Reset error code and open a water tap to cycle the heater in aneffort to purge air on new installations. Cycling hot water tap onand off multiple times may be necessary. If heater still faults withEA error code, have a licensed gas technician properly purge airout of the gas line leading to the water heater.4. Check three wire connections to ignition group on the lowerfront of the heat exchanger are secure.5. Check gas pressure, see chapter 3.12, page 21.6. Check venting specifications are met. Improper venting maycause premature failure of the flame sensor rod.7. Check that the minimum power fan speed has been adjusted tothe proper value. See page 34.8. Observe inside the viewing window of the heat exchanger whena hot water tap is opened. Sparking should be followed by asteady blue flame. If flame is unstable or yellow with proper gaspressure, confirm CO2 readings per section 6.4.

Ionization failure during operation. 1. Check gas type, see Fig. 2, page 5.2. Check three wire connections to ignition group on the lowerfront of the heat exchanger are secure.3. Check venting specifications are met. Improper venting maycause unstable burner flames and loss of flame ionization.4. Check that the minimum power fan speed has been adjusted tothe proper value. See page 34.5. Check gas pressure, see section 3.12, page 21.6. Check and adjust CO2 readings, see section 6.4, page 28.

Ionization error at standby. 1. Loose connection to the flame ionization rod. Verify that thethinner wire leading from the control unit is securely connected tothe flame sensor located on the lower front of the heat exchanger.See Fig. 63, page 46.2. Flame ionization rod or control unit may be damaged. ContactBosch Water Heating for further instruction.

Gas leakage error, gas valve circuitnot closing properly.

1. Disconnect power supply cord and check wire connections ongas valve and the two connectors on the control board.2. Flow water out of a hot water tap above the minimum activationpoint of 0.65 GPM. Measure voltage at the gas valve wire plugconnection. The voltage should measure 24VDC between the leftpair of wires and 24VDC between the right pair of wires when theunit is operating. If voltage is not proper, contact Bosch WaterHeating for further instruction.3. Gas valve may be defective, contact Bosch Water Heating forfurther instrucation.



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Electrical diagram

9 Electrical diagram

Fig. 58 Electrical scheme1 Intlet water temperature sensor2 Outlet water temperature sensor3 Exhaust temperature sensor4 Cascading output connection5 Cascading input connection6 Ionization sensor7 Water flow sensor8 Flue gas limiter9 Heat Exchanger Overheat Sensor (ECO)10 Gas valve12 Water valve13 Primary fan14 ON/OFF switch15 Secondary fan16 AC plug17 Main connection18 Ignition electrodes19 Ground post20 Antifreeze Kit connection21 Fuse22 Fuse

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Sensor resistance charts

43

10 Sensor resistance charts

Fig. 59

Fig. 60

Outlet temperature sensor characteristics

3 23 74 24 752576 26 772778 28 79 29 7

10 210 7112117

12 212 713 213 714 214 715215716 216 717217718 218 719 219 7

2 0 22 0 72 122 17

2 2 2

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37

Resistance (Kohm)

Tem

p ºF

0

5

10

15

2 0

2 5

3 0

3 5

4 0

4 5

50

55

6 0

6 5

70

75

8 0

8 5

9 0

9 5

10 0

10 5

110

Tem

p ºC

Inlet temperature sensor characteristics

3 23 74 24 752576 26 772778 28 79 29 7

10 210 7112117

12 212 713 213 714 214 715215716 216 717217718 218 719 219 7

2 0 22 0 72 122 17

2 2 22 2 72 3 22 3 72 4 22 4 7

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Resistance (Kohm)

Tem

p ºF

0

5

10

15

2 0

2 5

3 0

3 5

4 0

4 5

50

55

6 0

6 5

70

75

8 0

8 5

9 0

9 5

10 0

10 5

110

115

12 0

Tem

p ºC

6 720 608 78244

Sensor resistance charts

Fig. 61

Back Flow characteristics

3 23 74 24 75 25 76 26 77 27 78 28 79 29 7

10 210 711211712 212 713 213 714 214 715 215 716 216 717 217 718 218 719 219 72 0 22 0 72 122 172 2 22 2 72 3 22 3 72 4 22 4 72 5 22 5 72 6 22 6 72 7 22 7 72 8 22 8 72 9 22 9 73 0 2

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37

Resistance (Kohm)

Tem

p ºF

0

5

10

15

2 0

2 5

3 0

3 5

4 0

4 5

50

55

6 0

6 5

70

75

8 0

8 5

9 0

9 5

10 0

10 5

110

115

12 0

12 5

13 0

13 5

14 0

14 5

150

155

Tem

p ºC

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GWH 2400 ES Functional scheme

45

11 GWH 2400 ES Functional scheme

Fig. 62 Functional scheme

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Interior components diagram and parts list

12 Interior components diagram and parts list

12.1 Interior components

Fig. 63 Components1 Flue gas collector2 Heat exchanger3 Flame sensor4 Primary fan (Mixer)5 Outlet temperature sensor6 LCD display7 On/Off button8 Reset button9 Program key10 Flue gas limiter11 Heat exchanger overheat sensor (ECO)

12 Ignition electrodes13 Observation window14 Backflow temperature sensor15 Secondary air fan16 Gas valve17 Water valve with engine and temperature sensor18 Control unit19 Up button20 Down button21 LED

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47

Fig. 64 Appliance overview

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12.2 Components diagram

12.2.1 Group 1

Fig. 65 Components Diagram

9

9

8

5

12

3

6

7

9

10

12

9

14

16

17

11

13 15

15

4

6720902973.AA JF

Item Description Reference1 Front cover 8 705 431 264

2 Cover shield 8 705 506 857

3 Trade mark badge 8 701 103 140

4 Cover screw 8 703 401 170

5 Combustion cover 8 700 506 300

6 Combustion cover gasket 8 704 701 084

7 Observation window 8 705 600 003

8 Holding bracket 8 708 104 103

9 Screw 8 703 403 012

Table 21

10 Combustion cover clip 8 701 201 032

11 Grommet set 8 710 203 039

12 Exhaust accessory 8 705 504 151

13 Gasket exhaust 8 700 103 710

14 Inlet air cover 8 708 006 022

15 Inlet air gasket 8 700 103 166

16 Inlet air accessory 8 705 504 154

17 Mounting bracket 8 701 309 164

Item Description Reference

Table 21

6 720 608 782


49

12.2.2 Group 2


1

3

2

4

5

6

7

8

9

6720902974.AA JF

Item Description Reference1 Heat exchanger 8 705 406 356

2 Heat exchanger top gasket 8 704 701 052

3 Flue gas collector 8 705 700 153

4 Overheat sensor (ECO) 8 707 206 204

5 Heat exchanger bottom gasket 8 704 701 054

Table 22

6 Site window 8 701 000 401

7 Ignition group 8 701 302 249

8 Heat exchanger O-ring 8 700 205 147

9 Rubber grommet 8 710 303 027


Table 22

6 720 608 78250


12.2.3 Group 3


1514

1

3

4

6

7

8

2

12

9

10

11

13

16

17

5

6720902975.AA JF

Item Description Reference1 Main burner 8 708 120 642

2 Burner gasket 8 704 701 087

3 Primary fan 8 707 204 071

4 Backflow temperature sensor 8 707 206 459

5 Washer 8 704 701 097

6 Fan mount nut 2 915 011 006

7 Secondary fan 8 707 204 072

8 Screw 8 703 403 012

9 Gas / Air Mixer 8 705 700 170

Table 23

10 Air duct O-ring 8 700 205 149

11 Venturi 8 700 306 226

12 O-ring 8 700 205 224

13 Mixer / Fan gasket 8 704 701 059

14 Screw 2 910 642 150

15 Plate gasket 8 701 004 049

16 Air supply duct 8 705 700 155

17 Screw 2 910 952 122


Table 23

6 720 608 782


51

12.2.4 Group 4


9

2

14

2

1

3

3

4

5

6

7

8

11

11

1213

10

6720902976.AA JF

Item Description Reference1 Gas valve 8 707 021 019

2 Pressure tapping 8 703 404 219

3 Washer 8 700 203 041

4 Pressure balance tube 8 700 703 136

5 Pressure balance nut 8 703 300 041

6 Gas supply pipe 8 700 715 389

7 Gas valve washer 8 700 103 014

Table 24

8 Gas filter 8 700 507 002

9 Gasket 8 704 701 085

10 Gas / Fan connector 8 705 202 140

11 Washer 8 704 701 062

12 Regulation screw 8 703 404 220

13 O-ring 8 700 205 009

14 Screw 2 910 149 181


Table 24

6 720 608 78252


12.2.5 Group 5


Item Description Reference1 Water valve with engine 8 708 505 024

2 O-ring 8 700 205 147

3 Cold water pipe 8 700 715 394

4 Pipe connection clip 8 701 201 028

5 Hot water pipe 8 700 715 392

6 Temperature sensor 8 700 400 015

7 Outlet fitting 8 703 305 349

8 Inlet / Outlet washer 8 710 103 045

9 Wireform spring 8 701 300 025

Table 25

10 Inlet fitting with filter 8 703 305 356

11 O-ring 8 700 205 157

12 Watervalve clip 8 716 102 607

13 Water filter 8 700 507 001

14 Washer 8 700 103 764

15 O-ring 8 700 205 231


Table 25

6 720 608 782


53

12.2.6 Group 6


15

1

2

3

7

6

9

5

11

13

16

14

10

12

84

6720902978.AA JF

Item Description Reference1 Control unit 8 707 207 257

2 Fuse T2.5A 1 904 521 342

3 Fuse T1.6A 8 700 609 008

4 Power supply cables 8 704 401 371

5 Power supply cord 8 704 401 378

6 Fan cables 8 704 401 347

7 Wire harness 8 704 401 348

8 Jumper 8 704 401 376

Table 26

9 Electrode cables 8 704 401 346

10 Flue gas limiter 7 709 003 665

11 Cascading kit (optional) 7 709 003 617

12 Anti freeze kit 8 700 400 022

13 Remote control (optional) 8 707 207 153

14 Shaped seal (optional) 8 700 201 012

15 Screw (optional) 8 703 401 109

16 Printed circuit transceiver (optional) 8 708 300 123


Table 26

6 720 608 78254

Protecting the environment

13 Protecting the environment

Packing

The packing box may be fully recycled as confirmed bythe recycling symbol .

Components

Many parts in the heater can be fully recycled in the endof the product life. Contact your city authorities forinformation about the disposal of recyclable products.

6 720 608 782

Limited Warranty

55

14 Limited Warranty

General

Aquastar water heaters are warranted by theManufacturer (BOSCH) through BBT North America.BBT North America (BBTNA) will furnish a replacementheat exchanger and will furnish a replacement of anyother part which fails in normal use and service withinthe applicable periods specified below, in accordancewith the terms of this warranty. The BBTNAreplacement will be warranted for the unexpired portionof the original warranty. This warranty will be valid onlyfor water heaters in possession of the original purchaseras recorded on the warranty card.

The Heat Exchanger

If the heat exchanger fails within twelve (12) years afterthe original installation and operation, BBTNA willfurnish a replacement heat exchanger. However, if thewater heater is in an approved domestic hot waterrecirculation application, this heat exchanger warrantyis limited to five (5) years from date of originalinstallation and operation. If the water heater is installedin other than a single family dwelling, this heatexchanger warranty is limited to two (2) years from dateof original installation and operation.

Exceptions

This warranty will not apply:

• 1. to defects or malfunctions resulting from failure toproperly install, operate or maintain the unit inaccordance with the printed instructions provided;

• 2. to damage or abuse, accident, neglect or freezingand other acts of nature;

• 3. to damage resulting from operation with either theflame sensor rod or overheat sensor removed;

• 4. to failure of the heat exchanger resulting from theoperation of the water heater in a corrosiveatmosphere or at water temperatures exceeding themaximum rating, or if the water heater is not suppliedwith potable water;

• 5. to defects or damage cause by any attachmentor modification, including any energy-saving device.

• 6. to damage resulting from scale deposits and/orhighly mineralized / unsoftened water supply.

All Other Parts

If any other part fails within two (2) years after originalinstallation and operation, BBTNA will furnish areplacement part free of charge.

Service Labor Costs

This warranty does not cover any labor costsassociated with service, removal or re-installation ofpart(s). All such costs must be borne by the Purchaser.Additionally, this warranty does not cover any laborcosts associated with service, removal or re-installationof the original water heater or a replaced water heater.

How to Make a Claim

Any claim for warranty parts should be made to yourlocal dealer or distributor:

BBT North America Corporation

Bosch Group

Bosch Water Heating340 Mad River ParkWaitsfield, VT 05673TEL. 800-642-3111

www.boschhotwater.com

In most cases, the dealer or distributor will be able topromptly honor your claim and subsequently notifyBBTNA. However, all replacements are made subject tovalidation by BBTNA of in-warranty coverage. Thedamaged or defective item must be made available inexchange for the replacement.

Miscellaneous

No one is authorized to make any other warranties onbehalf of BBTNA. It is expressly understood that thereplacement warranty of BBTNA shall be in lieu of anyand all other warranties, express or implied, includingwarranties of merchantability or fitness for a particularuse or purpose, and further that BBTNA shall not beliable for any loss or damage directly or indirectly arisingfrom the use of the hot water heater, or for anyconsequential damages arising from such use(including damages from water leakage). BBTNA soleliability with respect to any defect shall be for thereplacement of the defective part(s). Some states donot allow such limitations and exclusions, so the abovemay not apply to you.This warranty gives specific legal rights. You may alsohave other rights which vary from state to state.

iNOTE: the water heater must be free ofdamaging scale deposits and not subjectto gas pressures greater than thoseshown on the rating plate, which must notbe altered, defaced or removed.

Recycled paper © 2007 BBT NORTH AMERICA,Waitsfield, VT all rights reserved

Replacement Parts available from:

BBT Termotecnologia Portugal, S.A.

Estrada de Cacia

3801 - 856 Aveiro - PORTUGAL

BBT North America CorporationBosch Group

Bosch Water Heating340 Mad River ParkWaitsfield, VT 05673TEL. 800-642-3111www.boschhotwater.com

Installer Checklist to be completed by installer upon installation

Serial Number ___ ___ ___ ___ ___ ___ ___ ___(8 digit serial number is located on rating plate on right side panel)

Gas Pressure Reading* Static__________ Operating__________

Building Water Pressure __________ Range if on Well system __________

Installing Company _____________________________________________

Installer name _____________________________________________

Address _____________________________________________

Phone _____________________________________________

* See Chapter 3.12, page 21 and gas pressure table (to be filled out by installer)

Installation manual should be left with the owner after the installation is tested and completed

(intended for variable flow applications) · 2011. 9. 16. · model gwh 2400 es ng and gwh 2400 es...

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