electric radiant floor warming installation manual · electric radiant floor warming contents ......

Installation Manual

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E l e c t r i c R a d i a n t F l o o r W a r m i n g

CCOONNTTEENNTTSSIntroducing HeatWeave UnderFloorMaterials and Cautions

PART 1Inspect the Mat and Sensor

PART 2Electrical Service Rough-in

PART 3Install the Mat

PART 4Final Wiring

PART 5Install the Insulation

PART 6Wiring Diagrams

PART 7Troubleshooting Guide

Please be aware that localcodes may require this product and/or the control to be installed or connected by an electrician.

HeatWeave UnderFloor is a safe andefficient electric floor-warming prod-uct for interior applications. It isintended only for installation under awood subfloor in residential and lightcommercial installations. It is notdesigned for other purposes such asroof snowmelting. Any use or installa-tion of this product other than what isstated in this installation manual willvoid the Limited Warranty.

HeatWeave UnderFloor is designedto deliver approximately 10 watts/sq. ft.of floor area. The temperature of thewarm floor is dependent on how wellthe floor is insulated, as well as theinsulating value of the flooring materi-als. If the joist space is sealed againstair leakage, exterior rim joists are insu-lated, and the underneath side of thefloor is insulated, most floors can beheated up to 15°F warmer than theywould otherwise be. Due to the insu-lating value of carpet, carpeted floorsmay not achieve the same temperaturerise. The floor may or may not achievethis temperature rise, and no represen-tations are made regarding the per-formance of any system.

For best results, install unfaced fiber-glass R-19 or R-13 (or equivalent)below the mat. Do not insulate belowthe mat with more than R-19, and nomore than R-11 total on top of the subfloor, including all floor coverings,rugs and other items placed on top.HeatWeave UnderFloor can be used toheat a room, as well as warm the floor,provided the heat loss of the room falls within the mat’s capabilities. Adesigner must determine if the outputfrom the HeatWeave UnderFloor is

Shieldedpower lead

INSULATION(MINIMUM R-13)

HeatWeave UnderFloor™ mats are only intended for installationbelow the subfloor.

Shielded power leads make for a tougher andsafer connection to the controls.

22 HeatWeave UnderFloor Installation Manual

IInnttrroodduucciinngg HHeeaattWWeeaavvee® UUnnddeerrFFlloooorr™

enough to match the heat loss of thestructure. Refer to page 3 for helpfuldesign guidelines.

The UnderFloor MatThe mat is composed of a heating

cable, a foil “radiator” to make a radiantsurface, and a set of power leads forconnection to the floor-sensing con-trol. These mats are manufactured insizes suitable to heat joist bays spaced12", 16", and 19.2" on center. Mats arerated either 120 VAC or 240 VAC. Select

the mat length to fit into the joistspace available. Multiple mats can beused to fill a larger area, however theymust be wired together in parallel (notin series) if they are to be connected tothe same control. NEVER combine120-VAC mats with 240-VAC mats.

Visit the Watts Radiant Web site atwww.wattsradiant.com, or call 800-276-2419 if there are any questions regard-ing the installation of the mat or itsrelated electrical components.

Subfloor

UnderFloor mat (with 2" air gap above the mat)

Insulation

Floor joist

Cross section of typicalUnderFloor installation

DDeessiiggnniinngg aa HHeeaattWWeeaavvee UUnnddeerrFFlloooorr SSyysstteemmHeatWeave UnderFloor Installation Manual 33

In general, HeatWeave UnderFloorshould be installed in all floor areaswhere floor warming is desired. It canbe installed to either warm the floor orto heat the space. If HeatWeave isbeing installed to heat the space, firstperform a heat loss calculation. UseRadiantWorks® or a similar program tocalculate the heat loss of the room(s).UnderFloor mats can be expected toprovide approximately 34 BTU/hr/sq.ft.This assumes the mats are installed per this manual, including the use ofproper insulation techniques. Makesure insulation is installed as shown onpage 10. There must be a “dead airspace” for UnderFloor mats to be effec-tive. This output also assumes a floorcovering other than carpet and pad.The output will be greatly diminishedwith a carpet floor covering and/or thelack of proper insulation.

Determine how much Mat isNeeded for the Installaton

To determine how much mat isneeded, take one of two approaches:

1. For a rough estimate, multiplythe wall-to-wall area by 75%–80%.Convert this to linear feet of mat andselect from the lengths of mat shownin the table on page 6.

2. For an accurate measurement,look under the subfloor to see wheremats can be stapled. Looking carefullyat each joist bay, measure the length ofopen area in that bay that can receive amat, and select the mat from the tableon page 6 that fits the space.

Remember that these mats cannot becut shorter to fit, nor modified in anyway to fit multiple joist bays. Do notinclude in these measurements areasthat contain items that would obstructinstallation of the mat (return air ducts,supply ducts, light fixtures, etc.). Wheremats are not installed, the floor abovewill not get very warm.

Wiring Multiple Mats TogetherEach mat is designed to be installed

in only one joist bay. The mats cannotbe cut shorter to fit a shorter joist bayor modified in any way to fill multiplejoist bays. However, more than onemat may be installed in a joist baywhere there are barriers such as cross bracing. A typical installation is shownbelow.

Since several mats will be requiredto warm the floor area, the mats mustbe wired together in parallel (not inseries) at a junction box below thefloor, then electrical wire fed from thereup to the floor-sensing control box.Select mats for the easiest wiring possi-ble. If all the power leads end up atone end of the room, it will be mucheasier to wire them together in thejunction box. The junction box mustbe accessible after all finishing work iscompleted. Be sure to position themats so that this is possible.

Mat Voltage RequirementsSelect either 120-VAC mats or

240-VAC mats (see table on page 6).Do not mix 120-VAC mats and controlswith 240-VAC mats and controls.Observe these general voltage guide-lines:

1. For areas totaling up to about190 sq. ft. (about 15 amps), use 120-VACmats with a 120-VAC FloorStat™.

2. For areas exceeding about 190sq. ft. and up to about 350 sq. ft., use240-VAC mats with a 240-VAC FloorStatto have mats totaling 14 amps or less.

3. Use 240-VAC mats and a 240-VAC GroupStat™ control system or a contactor system (see wiring diagramsin Part 6) for mats totaling more than14 amps at 240 VAC.

Regardless of the voltage require-ments in a particular installation, makesure the circuit breaker can handle theload. Follow all electrical codes fordetermining the size of the breaker.

Floor-sensing ControlsTo control the UnderFloor system,

install either a programmable or non-programmable, floor-sensing FloorStator GroupStat system. The sensorshould be installed per instructions inPart 2 (page 7).

Please reference the Watts Radiantcatalog, or contact a Watts Radiant dis-tributor for more information.

Floor joist

Cross bridging or blocks

Insulated around outside of area

Insulated underneath mat

Areas with ductwork or pipingmay not allow mat.

Insulated at ends

UnderFloor mats

Install mats 2" below subfloor


NEVER cut the mat, or remove the foil radiator, or modify the mat in any way. The mat must remain intact. However, the power leads may be cut shorter, if necessary, but never removed completely.

NEVER leave the mat rolled up or bunched in the joist bay. Make sure the mat is completely unrolled and is installed completely flat.

NEVER attempt to repair the mat if it is damaged. Call the factory for instructions.

NEVER install one mat on top of another or overlap the mat onto itself. Doing so will causedangerous overheating.

NEVER forget to install the floor sensor.

NEVER remove the nameplate label.

NEVER allow metal objects such as staples, metal pipes, ductwork, or straps to remain in contact with the foil radiator of the mat.

NEVER staple closer than 1/4" from the heating wire.

NEVER install the mat closer than 2" from the subfloor.

NEVER install the mat closer than 8" from the edges of outlet boxes and junction boxes used to mount surface lighting fixtures.

NEVER run mats across joists.

NEVER insulate below the mat with greater than R-19, and no greater than R-11 total on top of the subfloor, including all floor coverings,rugs, and other items placed on top.

ALWAYS enter mat and sensor resistance readings in the Mat and Sensor Resistance Log (see page 5) before, during, and after the installation process.

ALWAYS pay close attention to the voltage and amperage requirements of the breaker, the control, and the mat. For instance, do not supply 240 VAC to 120-VAC mats or controls.

ALWAYS make sure all electrical work is done by qualified persons in accordance with local building and electrical codes, Section 62 of CEC Part I, and the National Electrical Code (NEC), especially Article 424, Part IX of the NEC, ANSI/NFPA 70.

ALWAYS use copper only as supply conductors.

ALWAYS affix the warning label (included with this manual) to the control or other location where it is easily noticed in the area containing the mat.

ALWAYS seek help if a problem arises. If ever in doubt about the correct installation procedure to follow, or if the product appears to be damaged, the factory must be contacted before proceeding with the installation.

Please visit www.wattsradiant.com, or call the Design Department at 800-276-2419 if there are any questions or problems regarding the installation of the mat or its related electrical components. If the product appears to be damaged, the factory must be contacted before proceeding with the installation or proposed repair.

Read these cautions carefully before beginning the installation.

Never cut the mat!

NNOO!!

• HeatWeave UnderFloor mat(s).* See page 3 to determine how much mat isneeded for each joist space.

• Floor-sensing FloorStat control (pro-grammable or nonprogrammable, withbuilt-in GFCI), or GroupStat controls(programmable or nonprogrammable).

• GFCI circuit breaker. (FloorStat orGroupStat controls have a built-in GFCI;therefore, the GFCI-type circuit breakeris not recommended since two GFCIs

Materials and Tools Neededmay conflict and cause problems. Ifusing the FloorStat or GroupStat con-trols, use a standard circuit breaker.)†

• Floor sensor (included with control).• HeatWeave UnderFloor Installation Kit*

(includes an Installation Manual andNailTites™).

• Electrical junction box for power leads.• An extra-deep electrical box for the

floor-sensing control.• 12-gauge electrical wiring.

* Items available from HeatWeave. All other items are not included and can be purchased locally.† The FloorStat and GroupStat are approved for use in the U.S. and Canada, separate from the

HeatWeave Listed assembly.

• 3/4" conduit to protect power leads, ifrequired by local code.

• Contactor (relay) (optional). See Parts 4and 6.

• LoudMouth™ monitor.• Digital ohmmeter (multi-meter) able

to measure up to 20,000 ohms (Ω).• Various electrical/construction tools

(staple gun, tape measure, marker, wirestripper, screwdriver, drill with 1/4" and1/2" drill bits, and electrical fish-tape).

• Insulation (R-13 or R-19 fiberglass recommended).

Monitor the Wire!Throughout the installation process

it is very important to take resistancereadings of the mat and floor sensorwires to make sure they have not been damaged. Use a quality digitalohmmeter (multi-meter) able to meas-ure up to 20,000 ohms (Ω) to take these readings. Analog meters (with the moving needle) are not accurateenough for this product.

Use the LoudMouth™ MonitorThe LoudMouth is designed to monitorthe mat during the installation process.If the heating wire is cut or damagedduring installation, this device soundsan alarm. Ask about purchasing thisvaluable tool.

HeatWeave UnderFloor Installation Manual 55

MAT 1 MAT 2 MAT 3Mat Serial Number

Mat Size

Mat Voltage

Factory Mat Resistance Range

OUT OF THE BOX BEFORE INSTALLATION (ohms)Mat black to white

Mat black to green

Mat white to green

Sensor Wire

AFTER SENSOR AND MAT ARE INSTALLED IN JOIST BAY (ohms)Mat black to white

Mat black to green

Mat white to green

Sensor Wire

AFTER INSULATION IS INSTALLED (ohms)Mat black to white

Mat black to green

Mat white to green

Sensor Wire

Note: Wire colors listed are for 120-VAC mats. See directions above for the 240-VAC color combinations to check.

RETAIN THIS LOG TO RETAIN THE WARRANTY! DO NOT DISCARD!

MAT AND SENSOR RESISTANCE LOG

PPAARRTT 11:: IInnssppeecctt tthhee MMaatt aanndd SSeennssoorrEssential Product Informationand Warranty

Do not remove the nameplate labelfrom the power leads (see photo).Record the serial number, mat size, volt-age, and mat resistance range into theresistance log below for each mat andsensor wire.

To retain the Limited Warranty theseitems and the following resistancemeasurements MUST be recorded, aswell as all steps of this manual fol-lowed. Refer now to the LimitedWarranty on the back cover of thismanual for complete requirements.

MeasurementsAt the very least, take resistance read-ings (1) before beginning installation,(2) after the mat and sensor have beeninstalled in the joist bay, and (3) afterinsulation is installed.

Checking for BreaksMeasure resistance between the

black and white leads (black and blueleads for 240-VAC mats) and record thisbelow. This measurement should bewithin the range shown on the name-plate label. A cut or break in the wire isindicated by a resistance of “infinite”ohms (no continuity, or “OL” for “openline”).

Checking for Short-CircuitsMeasure resistances between the

black and green leads and between thewhite and green leads (blue and greenleads for 240-VAC mats) and recordthese below. These measurementsshould be “infinite” ohms (no continuityor “OL” for “open line”). A cut or pinchin the wire is indicated by a resistancevalue greater than zero but less thanthe mat resistance.

If the resistance is not correct, or ifthe wire has been cut or damaged,note the damaged area and call thefactory for further instructions.

Checking the Floor SensorThe FloorStat and GroupStat come

with a floor sensor. This must be testedprior to installation. Use a quality digital ohmmeter that is capable ofmeasuring at least 20,000 ohms (Ω),and measure between the lead wires ofthe sensor. The measurement variesaccording to the temperature sensed in the tip. The sensor resistance tableon page 6 gives a set of approximatevalues for comparison.

If no resistance is detected, or if theresistance value is very different fromthat shown in the sensor resistancetable, check the ohmmeter first tomake sure it was correctly set. Thencontact the factory for assistance.

Record the information from this nameplate label into the Mat and Sensor Resistance Log provided at right. Leave this nameplate labelattached to the power leads for later inspec-tion.

The Electric Radiant Heating Warning Labelmust be placed near, or on the face of the control.

To retain the Limited Warranty, resistance read-ings and other data MUST be recorded in theMat and Sensor Resistance Log below. Use theLoudMouth (right) to monitor the mat duringthe entire installation process.

The LoudMouth

Measure resistances

Circuit Overcurrent Protectionand GFCI Protection

The UnderFloor mat must be pro-tected by a ground fault circuit inter-rupter (GFCI). If the mats are directlypowered through the FloorStat orGroupStat controls, these already havean integral GFCI to protect the mats


PPAARRTT 22:: EElleeccttrriiccaall SSeerrvviiccee RRoouugghh--iinn(do not install a GFCI type circuit break-er to supply a FloorStat or GroupStatbecause the respective GFCIs may con-flict and cause problems). If a differenttype control or relay is used that doesnot have a built-in Class A GFCI, an indi-cating-type GFCI circuit breaker mustbe used to protect the mats. This GFCIbreaker serves as a local disconnect.

NOTE: Follow all local buildingand electrical codes.

It is recommended that the systembe installed on its own dedicated cir-cuit, directly from the circuit breakerpanel. However, small systems may beable to tap into an existing circuit.Consult an electrician. Make sure thereis adequate capacity for the mat(s) aswell as any other items that may usethis circuit. The mat(s) should not beinstalled in a circuit with another GFCI(breaker or outlet), lighting circuit (low-voltage, halogen, or other types thatuse ballasts or transformers that caninterfere), or motor circuit (exhaust fan,hot tub, etc.) due to possible interfer-ence which can cause the GFCI on thecontrol to false-trip.

The circuit breaker protecting themat(s) must be no larger than 20 amps.Load the circuit breaker with no morethan the following: 12 amps on a 15-amp circuit breaker, 16 amps on a20-amp circuit breaker. Additional circuit breakers will be required forlarger loads than these.

Select mats so that no more than 15 amps are run through a FloorStat orGroupStat control.

Large Systems on one Floor-sensing Control

For systems that are too large todirectly power through one FloorStat,but must be operated by one floor-sensing control, use the GroupStat master/subcontrols for best perform-ance. Contact a HeatWeave dealer orthe factory for more information. A

contactor (relay) may also be used.Consult an electrician concerning theuse of a contactor, and be sure to protect it with a GFCI breaker.

Install Electrical BoxesFloorStat box. Decide on the

location for the floor-sensing control.Usually this will be in the same room asthe floor being warmed, but it can bemounted almost anywhere as long as itis not in a confined space where air-flow is restricted. To reach this boxwith the mats, the mat power leads andthe sensor wire leads can both beextended if needed with the appropri-ate size wire at a junction box.

The control electrical box may be asingle-gang plastic deep box, but besure to follow all electrical coderequirements for box fill, grounding,etc. when determining the correct boxfor a particular application.

The control box should be locatedon interior walls, typically 60" from thefloor, according to code requirements.

NOTE: The FloorStat sensor wirecan be up to 50 ft. long, extendedwith 22- or 24-AWG wire.

GroupStat boxes. The GroupStatcontrols have a master floor-sensingcontrol and several subcontrols. Themaster control is usually located in thesame room as the floor being warmed,but may be located almost anywhereon an interior wall. It may be mountedin a single-gang plastic deep box and istypically located about 60" above thefloor, or according to local coderequirements. The floor sensor alsoconnects to this control.

The subcontrols may be locatedmost anywhere as long as they are notin a confined space where airflow isrestricted. The subcontrols supply thepower to the mats, so to reach thesecontrols with the mats, the mat powerleads should first go to a junction box(see page 9) and then to a subcontrol.(see instructions provided with theGroupStat controls).

Other junction boxes: It is highlyrecommended that a separate steelelectrical junction box be mountedbelow the subfloor or in the wall in alocation to which the mat power leadscan be routed. A separate wiring drop

Floor Sensor Resistance Values

Temperature Typical Values

55°F (13°C) 17,000 ohms65°F (18°C) 13,000 ohms75°F (24°C) 10,000 ohms85°F (29°C) 8,000 ohms

UnderFloor Mat Sizes, Amperage Draw, and Resistance Ranges.

Amperage ResistanceMat Size Draw Range (ohms)

120 VAC12" × 5.5 ft. 0.4 247–30212" × 8 ft. 0.6 167–20412" × 10.5 ft. 0.9 121–14812" × 13 ft. 1.1 97–11912" × 16 ft. 1.3 80–9812" × 19 ft. 1.5 67–82

16" × 4 ft. 0.4 258–31516" × 6 ft. 0.6 173–21116" × 8 ft. 0.8 126–15416" × 9.5 ft. 1.0 101–12316" × 12 ft. 1.3 82–10116" × 14 ft. 1.5 69–8516" × 16 ft. 1.7 63–7816" × 18 ft. 1.9 53–6516" × 19.5 ft. 2.1 45–56

19.2" × 4.5 ft. 0.7 170–20719.2" × 6.5 ft. 0.9 127–15519.2" × 8 ft. 1.0 103–12619.2" × 9.5 ft. 1.3 83–10219.2" × 11.5 ft. 1.5 71–8719.2" × 13 ft. 1.7 63–7819.2" × 14.5 ft. 1.8 54–6619.2" × 16 ft. 2.1 45–56

240 VAC12" × 10.5 ft. 0.4 500–61112" × 16 ft. 0.6 336–41112" × 21 ft. 0.9 243–29712" × 26 ft. 1.1 195–238

16" × 8 ft. 0.4 521–63616" × 12 ft. 0.6 362–44316" × 16 ft. 0.8 253–31016" × 19.5 ft. 1.0 207–25316" × 24 ft. 1.3 168–206

19.2" × 6.5 ft. 0.4 526–64319.2" × 9.5 ft. 0.6 359–43919.2" × 13 ft. 0.9 256–31319.2" × 16 ft. 1.0 207–25319.2" × 19 ft. 1.3 167–20419.2" × 23 ft. 1.5 143–17419.2" × 26 ft. 1.7 127–156

can be made from the control boxdown to this junction box. This makesit much easier to install the system.

Bottom Plate WorkDrill a hole up through the wall bot-

tom plate to route the power wiringfrom the control box to the mats belowthe floor.

Rough-in WiringInstall electrical wiring from the

power source breaker to the controlelectrical box, and then to the junctionbox below the floor for the mat leads.Leave 6"–8" of extra wire at the controlbox and junction box. Refer to thewiring diagrams in Part 6 for assistance.

Install FloorStat SensorA floor sensor comes with the

FloorStat control and must be installedcorrectly to control the floor tempera-ture. Remember to locate the sensor ina floor where a mat is located. The fol-lowing are recommended methods forinstalling the sensor. Other equivalentmethods may be used.

Before installing the sensor, makesure to test it with an ohmmeter.See page 5,“Checking the FloorSensor.”

Method 1. Since a sensor may bedifficult to install in some existingfloors, the sensor may be placed underthe subfloor. However, keep in mindthat the temperature the sensor gives


will not be a true floor surface temper-ature and the floor-sensing controlmay need to be adjusted accordingly.

Drill a hole through the bottomplate of the wall to route the sensorwire. Feed the sensor wire down fromthe control box through the floor. (Afish-tape may need to be used in orderto do this.)

The most accurate method is to drilla 3/4"–1"-long hole at an angle into thebottom of the subfloor (drilling at anangle prevents puncturing throughfloor surface). Locate this hole in a joistbay directly over where a mat will beinstalled, about 2" from the joist. Insertthe sensor into the angled hole andseal it with adhesive. Insulate the sen-sor with additional “blueboard” or fiber-glass insulation, 1"–2" thick and 6"square, adhered and sealed under thesensor. This will isolate the sensor fromthe heated joist space and give a truerfloor surface temperature.

Method 2. If it is not possible todrill a hole to set the sensor in the sub-floor, it may be held flat to the subfloorwith a nylon wire clip. Locate the sen-sor in a joist bay directly over where amat will be installed, about 2" from thejoist. Insulate the sensor with addi-tional “blueboard” or fiberglass insula-tion, 1"–2" thick and 6" square. This willhelp isolate the sensor from the heatedjoist space.

Method 3. If possible, install thesensor directly into or under the floorcovering area.

If the floor surface is tiled, a grout

Method 3: Remove the grout 1/4" to 1/2"deep. Install sensor. Reinstall grout over thesensor and sensor wire.

line can be removed and the sensorlaid into this grout line.

Drill a hole into the wall behind the baseboard trim area and directly belowthe control electrical box.

Feed the sensor through the knock-out, down to the hole that was drillednear the floor, and out into the floorabove where the heating mat will beinstalled. Locate the sensor at least 1 ft.from outside walls and near the centerof a joist space.

Complete the rest of the installationbefore covering or regrouting over thesensor.

Subfloor

Floor surface

Sensor tipBead of constructionadhesive

Angled hole drilledfor floor sensor

Floor joist

Minimum 1"-thickinsulation

Insulation (6" square)

Diagram showing Method 1 for installing the floor sensor into the subfloor.


PPAARRTT 33:: IInnssttaallll tthhee MMaattSee Part 6 for typical wiring dia-

grams.Observe the following rules, plus all

other electrical/building codes and theCautions on Page 4 when installing themat(s):

Do not allow the foil radiator ofthe mat to be mounted such thatit contacts metal objects such asnails, staples, metal pipes, heat-ing ducts, and joist straps.

Keep the mat at least 2" awayfrom recessed fixtures (lights,etc.), ventilation openings, andother openings.

Keep the mat at least 8" awayfrom the edges of outlet boxesand junction boxes used tomount surface lighting fixtures.

Keep the mat at least 6" awayfrom heat-sensitive items such astoilet rings, flexible ducting, andother items rated less than 194°F(90°C). Consult manufacturers ofthose items.

REMEMBER:Pay careful attention to areaswhere ductwork, wiring, or otheritems do not allow the mat to beinstalled. Keep in mind thatwhere mats are not installed, thecorresponding floor area abovewill not get very warm.

Before installing the mat, inspect alljoists as well as the underside of thesubfloor for nails, screws, or other sharpobjects that protrude into the joist cav-ity. These items can damage the mat,

Test fit the mat between the joists before stapling the mat to the joists.

1. Measure between the floor joistswhere mat(s) will be installed. Measurethe width of the mat selected to fitbetween these joists. The differencebetween these measurements deter-mine how much mat mesh remains forstapling to each side of the joists.Because the distance between floorjoists can vary, taking these measure-ments will help ensure the mat will becentered between the joists. It is alsoprudent to test fit the mat by holdingthe mat up into the joist cavity.

2. If the mat begins near the rim joist,measure about 6" out from that rimjoist. This will allow enough room forthe mat power leads, and will preventunnecessary heating of the wall cavityabove the floor.

3. Measure 2" below the subfloor andmark the joists on both sides of thejoist cavity.

4. To help hold up the power leadswhile installing the mat, fasten oneNailTite over the power leads

5. Hold the mat up along one joistand begin stapling the mat mesh alongthe 2" mark from the subfloor. Stapleevery 4" to 6" for about 2 ft. to getstarted.

and must be removed, cut off, or bentflat against the underside of the sub-floor or the side of the joist(s).

Do not staple, cut, or damage thefoiled heating portion of the mat in anyway. The fiber mesh of the mat is theportion that will be used to staple themat to the joists.

Do not leave the mat rolled up orbunched up in any way in the joistbay. Doing so will cause dangerousoverheating and possible damage.Mats must be installed so that theyare completely flat across the joistcavity.

1.

2.

3.

4.

5.


6. At the other end of the mat, place anail into the joist at 2" below the sub-floor. Hang the fiber mesh of the matonto the nail. This will make it mucheasier to staple the rest of the mat.

7. Continue stapling the mat mesh at2" below the subfloor, every 4" to 6".Then remove the nail at the end thatheld it up.

8. Raise the mat to the other joist andstaple the mat mesh 2" below the sub-floor.

9. Using the same techniques, staple up all other mats.

Power Lead InstallationIf not already done so, mount a junc-

tion box below the subfloor withinreach of the mat power leads. Installmore than one junction box, if needed,for larger jobs. The junction box mustremain accessible in accordance withelectrical codes, so consider the loca-tion of the junction box carefullyshould the ceiling be finished afterinstallation of the mat(s).

Route the power leads from themat(s) to the junction box following allelectrical and building codes using

Junction box with multiple sets of mat lead wires, connected in parallel, and connected to thepower supply.

conduit and additional electrical boxeswhere required.

For multiple mats, follow all electri-cal codes concerning “box fill” maxi-mums. Connect the leads in parallel(black-to-black, white-to-white), andnot in series.

Connect the mat leads to the powerdrop from the control electrical box orGroupStat subcontrol, or contactor.

Again, do not overload the control.The FloorStat and GroupStat controlmust not be loaded with over 15 ampsof mats.

6.

7.

8.

9.

Install the ControlInstall the control(s) for the mats

according to the wiring diagrams pro-vided with the controls. See the dia-grams are shown on pages 11–13.

Connect the power supply leads, thepower drop to the mat junction box,and the floor sensor wire to theFloorStat. Follow proper wiring proce-dures.

It is a good idea to overwrap thewire nuts with electrical tape to furthersecure the wires into the wires nutsbefore pushing the control back intothe electrical box.

If a GroupStat is used, connect thepower supply leads and power drop for the mats to the sub-control. Run a3-wire 22-gauge or 24-gauge wire, orsimilar low-voltage cable, to connectthe subcontrol(s) to the master control.


PPAARRTT 44:: FFiinnaall WWiirriinnggConnect the floor sensor wire to themaster control.

Test the SystemAfter the controls are installed and

connected, energize the system brieflyto test operation of all components.

Refer to the installation sheets pro-vided with the FloorStat for proper setting.

Without floor insulation, the mat willnot heat the floor. When the FloorStatcalls for heat to the mat, the mat willbegin to feel warm to the touch within1 to 2 minutes or so. If this does notoccur, recheck the FloorStat settings,wiring connections, and power supply.

Apply the Warning LabelApply the Radiant Heating Warning

Label (included with this manual) tothe control or nearby location.

Install R-13 to R-19 fiberglass insula-tion below the mat. Gently press theinsulation up to the mat for best resultsand secure in place with rods, staples,or other method. A gap between theinsulation and mat is acceptable butwill not give the best heating results.

Make sure to insulate at the end ofall heated joist cavities. Install insula-tion vertically in these areas to seal theends of the heated joist areas or, 6"after the mat “stops” in a joist space,push the insulation up tight againstthe subfloor and staple to the subfloor.This ensures that no heated air canescape from the heated joist space.If this is not done, much heat will“escape” horizontally through bandjoists, rim joists, exterior walls, andopen ends of joist spaces, and the floorwill not warm as it should.

Seal openings around pipes, wastelines, ducts, joist blocking, and all othergaps with silicone caulking or urethanefoam.

PPAARRTT 55:: IInnssttaallll tthhee IInnssuullaattiioonn

The mat power leads and sensor wire connectedto the control at the electrical box.

REMEMBER: Proper insulating and sealing of the floor cavity is necessary forthe performance of HeatWeave UnderFloor mats.

HeatWeave UnderFloor Installation Manual 1111PPAARRTT 66:: WWiirriinngg DDiiaaggrraammssTypical Electric Wiring Diagram with FloorStat Control (120 V)Dedicated 120-V, 20-amp (maximum) circuit (must be GFCI protected unless a GFCI FloorStat is used).

Typical Electric Wiring Diagram with FloorStat Control (240 V)Dedicated 240-V, 20-amp (maximum) circuit (must be GFCI protected unless a GFCI FloorStat is used).

All electrical work must be done by a qualified licensed electrician in accordance with local building and electrical codes, andthe National Electrical Code (NEC), especially Article 424, Part IX of the NEC, ANSI/NFPA70 and Section 62 of CEC Part 1.



Typical Electric Wiring Diagram with GroupStat Control (240 V)Dedicated 240-V, 20-amp (maximum) circuit (must be GFCI protected unless a GFCI FloorStat is used).


HeatWeave UnderFloor Installation Manual 1133Typical Electric Wiring Diagram with FloorStat Control and Contactor(s) (240 V)Dedicated 240-V, contactor circuit is GFCI Class A or B protected.



Illustrations showing how to connect the LoudMouth monitor to two mats (left) , and how to connect the LoudMouth tothree mats (right). The LoudMouth can monitor no more than three mats simultaneously. Do NOT leave the power leadsconnected in “series” like this when making final wiring connections; the mats will not heat sufficiently. When making finalwiring connections, mats must be wired in parallel.

How to Connect the LoudMouth Monitor to the Mat Power Leads

ProblemMat resistance measurement isoutside the range printed on thenameplate label.

Floor is not getting warm.

Floor heats continuously.

Control is not working correctly.

Control is not working at all.

GFCI conflicts and false-trips.

Possible CauseAn analog ohmmeter (using a moving needle)was used to take the reading.

If measurement shows an open or short circuit,the heating wire has been damaged.

If measurement is just a little low or high, roomtemperature has affected the resistance.

The mat may be wired in series or “daisychained” with another mat, or may be wired inparallel with another mat. Either will providefalse resistance readings.

Mat heating wire has been damaged.

GFCI has tripped, indicated by a light on thecontrol. Light may be labeled “GFI,” may bebelow the words “Stand by,” or on the buttonlabeled “Test.”

Incorrect voltage supplied, or mismatched electrical components used.

Mats are wired in “series” or “daisy chained”(end-to-end).

Floor sensor is loose or broken. If control has a digital display, it may indicate “LO.”

Incorrect wiring. The control was “bypassed”when it was wired to the power supply.

Defective control.

If a programmable control, the programmingmay be incorrect.

Incorrect voltage supplied, or mismatched components used.

Floor sensor is not wired properly, or is notworking properly.

Loose connection(s) on line side and/or loadside of control.

No power is supplied.

Floor sensor is not wired properly, or is notworking properly.

Defective control.

More than one GFCI on the circuit.

Loose wiring connection(s).

An electric motor or a ballasted light source issharing the circuit with the control.

SolutionObtain a digital ohmmeter able to read 0 to 20,000 ohms and remeasure the resistance.

Record resistance between all wires and contact the manufacturer.

Make the room temperature 75°–85°F, or contact the manufacturer.

Make sure resistance measurements are for only one mat at a time. Disconnect any other mats.

Measure mat resistance. Check for both “open circuit” and “short circuit” as detailed earlier in thismanual. If damaged, record resistances between all wires and contact the manufacturer.

Check for loose wire connections. Reset the GFCI on the control or circuit breaker. If it trips again,check for a short circuit in the mat as detailed earlier in this manual. If mat is damaged, recordresistance between all wires and contact the manufacturer. If mat is not damaged, replace theGFCI control. Also see “GFCI conflicts” below.

Measure “line” voltage, then measure “load” voltage. Both 120-V mats and controls have black andwhite leads. 240-V mats have black and blue leads, and 240-V controls have black and red leads.

Multiple mats must be connected in “parallel” (or black-to-black, white-to-white).

Pull the sensor wires loose from the control and reinsert them. If this does not solve the problem,loosen the sensor wires from the control and measure resistance across the sensor wires. For aHeatWeave control sensor the resistance should be between 17,000 ohms (at 55°F/13°C) and8,000 ohms (at 85°F/29°C). See sensor wire resistance values on page 6.

Make sure wiring connections are correct. Consult the wiring diagram on the back of the control,the instructions that came with the control, or the wiring diagrams in Part 6 of this manual tomake sure the four connections are correct.

Return control to dealer for replacement.

Carefully read and follow control programming instructions.

Measure voltage at the control and make sure it matches the control voltage rating, and the matvoltage rating. Make sure electrical components are compatible. Both 120-V mats and controlshave black and white leads. 240-V mats have black and blue leads, and 240-V controls have blackand red leads.

Make sure only one floor sensor is connected to the control. Also see “Sensor is loose or broken” above.

Remove and reinstall the wire nuts at each connection. Make sure the wire nuts are tight.Check all connections back to the breaker.

Check circuit breaker. Measure voltage at the control. Check all connections between breaker and control.

The control can only read the signal from a single floor sensor. Make sure only one floor sensor isconnected to the control. Also see “Sensor is loose or broken” above.

Return control to dealer for replacement.

GFCI units will sometimes trip when there is nothing wrong with the equipment on the circuit,but when there is more than one GFCI on the same circuit. Reroute power to avoid having morethan one GFCI on the circuit.

Remove and reinstall the wire nuts at each connection. Make sure the wire nuts are tight.Check all connections back to the breaker.

Electric motors and other electrical devices can cause a GFCI to false-trip. Run a dedicated circuitto the floor-warming system.


If problems arise with the mat or itsrelated electrical components, pleaseconsult this troubleshooting guide. Ifnot qualified to perform electrical work,it is highly recommended that a quali-fied, licensed electrician be hired.

Any electrical troubleshootingwork should be performed with the

power removed from the circuit,unless otherwise noted.

Although this troubleshooting guideis provided to assist with problemsexperienced with a HeatWeave floor-warming system, results are never guar-anteed. Watts Radiant does not assumeany liability or responsibility for dam-

age or injury that may occur from usingthis guide.

If problems with the system persist,call the manufacturer at 800-276-2419.

PPAARRTT 77:: TTrroouubblleesshhoooottiinngg GGuuiiddee

Watts Radiant, Inc.4500 E. Progress PlaceSpringfield, MO 65803-8816800-276-2419 (toll-free phone)

417-864-6108 (phone)

417-864-8161 (fax)

www.wattsradiant.com

Copyright © 2006 Watts Radiant, Inc. HeatWeave UnderFloor Installation Manual HWUFMAN0306 Effective 03/16/2006

HeatWeave products are patented under foreign and U.S. patents including numbers 6,303,905, 6,300,598, and 5,908,573.Trademarks and U.S. Registered Trademarks and copyrighted material herein are the property of Watts Radiant, Inc.

E l e c t r i c R a d i a n t F l o o r Wa r m i n g

Mat layout grid — use this to draw a scaled layout of the room to be heated. = ___

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