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1 Exam Prep – Intermediate Mechanical Study Guide 1

1 Exam Prep

Intermediate Mechanical Study Guide

Tabs and Highlights

These 1 Exam Prep Tabs are based on Intermediate Mechanical Study Guide.

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down that row placing the tabs at the locations listed below. Place each tab in your book setting it down one

notch until you get to the last tab (usually the index or glossary). Then start with the highlights.

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outline of your appropriate module. Now locate and highlight several items listed in the outline just before

the topic, and just after. See how the topic fits in the outline and how it relates as a concept to the broader

concept spelled out in the outline. If you take a few minutes to do this, when you take the test key words in

the test questions will remind you of where the information is in the manual!

1 Exam Prep Tab Section

Contents I

Basic Electricity 03106-07

Introduction to Cooling 03107-07

Introduction to Heating 03108-07

Introduction to Hydronic Systems 03203-07

Alternating Current 03206-07

Introduction to Control Circuit 03208-07

Trouble Shooting

Troubleshooting Gas Heating 03209-07

Basic Installation and Maintenance 03212-07

Practices

Refrigerants and Oils 03301-08

Retail Refrigeration Systems 03304-08

Commercial Hydronic Systems 03305-08


1 Exam Prep Tab Section

Steam Systems 03306-08

Water Treatment 03308-08

Troubleshooting Electronic Controls 03309-08

Construction Drawings and 03401-09

Specifications

System Startup and Shutdown 03406-09

Index 799

This concludes the tabs for this document. Please continue with the highlights below.

Section Highlight

03106-07 Basic Electricity

2.1.0 Electrical Power Generation and Distribution: Devices known as transformers are

used to step up the voltage down to lower levels as it reaches electrical substations and

eventually our homes, offices, and factories.

2.2.0 Current, Voltage, and Resistance: When a difference in the number of electrons exists

between two points, electrons …. Between the two points is called voltage.

In the common 12V car battery, a chemical reaction causes one of the poles to be

negative with respect to the other.

Current is expressed in amperes or amps (A), voltage is expressed in volts (V), and

resistance is expressed in ohms.

3.0.0 AC and DC Voltage: The kind of electricity produced by a battery is known as direct

current.

The electricity supplied by your local utility is alternating current (AC). Almost all

HVAC devices use AC … such units contain special circuits called rectifiers that convert

AC to DC.


Section Highlight

4.1.0 Ohm’s Law

Figure 4: Ohm’s Law

4.2.0 Electrical Power: Power formula: Power (P) = voltage (E) x current (I).

5.0.0 Electrical Circuits: An electrical circuit is a closed loop that contains a voltage source, a

load, and conductors to carry current.

5.1.0 Series Circuits: A series circuit provides only one path for current flow. The total

resistance of the circuit is equal to the sum of the individual resistances.

5.2.0 Parallel Circuits: In a parallel circuit, each load is connected directly to the voltage

source.

7.2.0 Switches: Switches stop and start the flow of current to other control devices or loads.

The simplest type of switch is one that makes (closes0 or breaks (opens) a single

electrical unit … Figure 13 shows some of the common switch arrangements, including:

1-3.

7.2.2 Fuses and Circuit Breakers: Fuses and circuit breakers protect components and wiring

against damage from current surges or short circuits.

A problem known as a ground fault occurs when a live conductor touches another

conducting substance … are installed for such problems.

7.2.5 Transformers: A transformer is used to raise or lower a voltage … around a common

iron core.

8.1.0 The Effect of Current: Electrical current flows along the path of least resistance to

return to its source.

8.2.0 Safety Practices: Here are some general safety practices to o\follow whenever you are

working with electricity: (8 bullets).

9.0.0 Circuit Diagrams

9.2.0 Simplified Schematic Design

Figure 25 – Circuit diagram

Figure 26- Ladder Diagram


Section Highlight

11.0.0 Electrical Measuring Instruments

11.1.0 Ammeter: Ammeters are often used to check motor circuits.

11.2.2 Resistance Measurements: An ohmmeter is used to check continuity in a circuit.

03107-07 Introduction to Cooling

2.1.1 Temperature: On the Fahrenheit scale water boils at 212 F and freezes at 32 F.

2.1.2 Heat Content: Btu is the amount of heat needed to raise the temperature of one pound of

water one degree Fahrenheit.

2.1.3 Sensible and Latent Heat: The increase in temperature from O F to 32 F registered by

the thermometer is called sensible heat … is called latent heat.

If we continue to add heat after all the water has been converted to steam … changed into

vapor.

Subcooling is the reverse of superheat.

Figure 4 – Change of state terminology.

2.2.0 Heat Transfer: Heat transfer is the movement of heat from one place to another, either

within a substance or between substances.

2.2.1 Conduction: Conduction is a means of heat transfer in which heat is moved from

molecule to molecule within a substance.

2.2.2 Convection: Convection is the transfer of heat by the flow of liquid or gas caused by a

temperature differential.

2.2.3 Radiation: Radiation is the movement of heat in the form of invisible rays or waves,

similar to light.

2.2.5 Rate of Heat Transfer: One ton of refrigeration is defined as 12,000 Btuh.

2.3.0 Pressure: Pressure is defined as force per unit area. This is normally expressed in pounds

per square inch.

2.3.1 Atmospheric Pressure: Atmospheric pressure can be measured with a barometer.

For this reason, it is often referred to as barometric pressure.

2.3.2 Gauge Pressure: Positive gauge pressures, those above zero are expressed in pounds

per square inch … in inches of mercury vacuum or in Hg vac.


Section Highlight

2.3.3 Pressure/Temperature Relationships: the boiling temperature of a liquid will drop

as the pressure on it decreases.

2.3.4 Movement of Fluids: Differences in pressure cause the flow of fluids. This flow is

always from a higher pressure to a lower pressure.

2.4.2 Gauge Manifold Set: The compound pressure gauge is used to measure system low-side

(suction) pressures, including any vacuum that exists in a system.

Most gauge manifold sets and service hoses are color-coded. The low-pressure compound

gauge, hand valve, and low-pressure hose port are blue.

Red is the color used to mark the high-pressure gauge, hand valve, and hose port.

Four-valve manifolds and related service hose sets are color-coded as follows: Blue (low

pressure), red (high pressure), yellow (charging), and black (vacuum).

Figure 12 – Basic refrigeration cycle

3.1.0 System Components:

- Evaporator

- Compressor

- Condenser

- Metering device

The type of lines are:

- Suction line

- Hot gas line

- Liquid line

3.2.0 Refrigeration Cycle

3.2.1 Basic Operation: The refrigeration cycle is based on two principles: (2 bullets).

Figure 13 – Typical air conditioning cycle for HCFC-22 (R-22) refrigerant

4.0.0 Refrigerants

4.3.0 Fluorocarbon Refrigerants: Man-made (synthetic) refrigerants in popular use today are

fluorocarbons or a mixture of … changed molecule is called s halocarbon, short for

halogenated hydrocarbon.

Fluorocarbon refrigerants fall into three groups, CFCs, HCFCs, and HFCs, based on their

chemical structure.


Section Highlight

4.5.0 Identifying Refrigerants

Table 3 – Color Codes for Common Refrigerant Containers

4.6.0 Refrigerant Safety Precautions

5.0.0 Compressors: Five types of compressors are commonly used in mechanical refrigeration

systems: (5 bullets).

5.1.0 Reciprocating Compressors: They use one or more pistons moving back and forth

within a cylinder.

5.2.0 Rotary Compressors: There are two types of rotary compressors: stationary vane and

rotary vane.

5.3.0 Scroll Compressors: achieves compression by the use of two spiral-shaped parts called

scrolls.

5.4.0 Screw Compressors: use a matched set of screw-shaped rotors, one male and one female

enclosed within a cylinder.

5.5.0 Centrifugal Compressors: use a high-speed impeller with many blades that rotate in a

spiral-shaped housing.

6.0.0 Condensers: Condensers are used for removing heat from the refrigeration system.

7.0.0 Evaporators: are used to extract heat from the conditioned space.

8.2.1 Thermostatic Expansion Valve: It is designed to maintain a constant superheat.

9.0.0 Other Components

9.5.0 Oil Separator: Their use is mainly in refrigeration and industrial systems.

9.9.0 Compressor Muffler: Mufflers are used most often in systems with open or semi-

hermetic reciprocating compressors.

10.0.0 Controls: Primary controls start or stop the refrigeration cycle either directly or

indirectly by sensing temperature, humidity, or pressure, or by measuring time.

Secondary controls regulate and protect the cycle and its components.

10.1.0 Primary Controls: Primary controls include the following: (4 bullets).

11.0.0 Piping

11.1.0 Basic Principles: Keep them simple and pitch horizontal lines in the direction of flow.


Section Highlight

11.5.0 Insulation: The three major considerations in refrigerant piping layout are compressor

protection, oil return, and pressure drop.

Figure 49 – Piping layout

03108-07 Introduction to Heating

2.1.1 Conduction: Conduction is the flow of heat from one part of a material to another part

or substance in direct contact with it.

An example of conduction is the transfer of heat from the gas burners to the heat

exchangers in a furnace.

2.1.2 Convection: Convection is air motion due to the warmer portions rising and the denser,

cooler portions falling.

2.1.3 Radiation: Radiation is the transfer of heat through space by wave motion.

2.2.0 Temperature: There are times when it may be necessary to change from one scale to the

other. These conversions can be done using the following formulas: (Equation).

2.3.0 Heat Measurement: The unit of measurement of heat in the inch-pound system is the

British thermal unit (Btu). One Btu is the amount of heat required to raise the temperature

of one pound of water 1 F.

2.4.0 Combustion: Combustion is the burning of fuel to create heat.

2.4.1 Complete Combustion: Complete combustion takes place when carbon combines with

oxygen to form carbon dioxide.

2.4.2 Incomplete Combustion: Incomplete combustion results from lack of oxygen and

causes undesirable products to form.

2.4.4 Flames: Pressure-type oil burners burn with a yellow flame, while gas burners burn with

a blue flame that has a slight orange tip.

2.5.0 Fuels

2.5.1 Gaseous Fuels: There are three types of gaseous fuels: natural gas, manufactured gas,

and liquefied petroleum.

- Natural gas

- Manufactured gas

- Liquefied petroleum


Section Highlight

2.5.2 Fuel Oils: There are six common grades of oil: Nos. 1, 2, 4, 5 and g. the lighter-weight

oils have a higher API gravity. (6 bullets).

3.0.0 Forced-Air Furnaces: In a forced-air furnace, cooled air-return air from the space being

… to the space through the supply ductwork.

3.2.0 Heat Exchangers: The heat exchanger is the part of the furnace where combustion takes

place.

3.3.0 Condensing Furnaces: Condensing furnaces are equipped with a secondary heat

exchanger made of stainless steel … looks like refrigeration condensing coil.

The latent heat removed by the condensing process is transferred to the conditioned air.

3.4.0 Fans and Motors

3.7.0 Humidifiers: Humidifiers are used to add moisture to outside air.

3.8.0 Installation

3.8.2 Safety Controls: Some of the furnace safety controls include the following: (4

bullets).

4.0.0 Gas Furnaces: In a gas furnace, gas fuel is supplied at low pressure into a burner head,

where it is mixed with the air required for combustion.

4.6.2 Manifold Pressure: One way to check the manifold pressure is to connect a manometer

to the pressure is to connect a manometer … It is calibrated in w.c.

5.0.0 Oil Furnaces: Electrodes located at the point where the oil spray enters the combustion

chamber provide a high-voltage spark that ignites the oil.

5.1.0 Oil Burner Operation: A high-pressure gun type burner forces oil through the nozzle

under pressure … Combustion air is supplied by a vane fan, creating turbulence and

complete mixing action.

5.1.4 Ignition System: The ignition system for high-pressure burners consists of a step-up

transformer connected to two electrodes.

5.4.0 Oil Safety Controls: Electric furnaces differ from fuel furnaces in that no combustion is

required.

6.1.0 Heating Elements

7.0.0 Hydronic Heating Systems: Another type of residential heating system heats water …

called a hydronic heating system.


Section Highlight

03203-07 Introduction to Hydronic Systems

1.0.0 A hydronic system uses pipes to transport heated or cooled fluid.

2.1.0 Water: Water itself is non-corrosive to most materials used in hydronic systems.

Although nitrogen is relatively inert, the dissolved oxygen will cause corrosion and

rusting … These systems are no longer used.

2.3.0 Head Pressure: Head pressure (or head) is another measure of pressure … column of

water 2.31’ high will produce a pressure of 1 psi.

Figure 3 – Relationship of head pressure in feet to pounds per square inch

2.4.0 Static pressure: Static pressure levels in a system decrease as we move from the lowest

point … the static pressure is 0 psi.

3.0.0 Hot-Water Heating Systems

3.1.0 Gravity Hot-Water Systems: In a gravity hot-water system water contained in the boiler

is heated to the operating temperature needed for use in the system.

3.2.0 Forced Hot-Water Systems: When a zone thermostat calls for heat the system

circulating … through a zone control valve to terminal devices located in the zone.

4.1.0 Hot-Water Boilers: A boiler heats water using gaseous fuels, oil fuels, solid fuels, or

electricity.

4.1.2 Cast-Iron Boilers: cast-iron boilers are formed by assembling individual cast-iron heat

exchanger sections together … small residences up to large commercial systems of

13,000 MBh.

4.2.0 Boiler Operating/Safety Controls and Accessories

4.2.2 Pressure (Safety) Relief Valve: A pressure (safety) relief valve is used to protect the

boiler and the system … maximum working pressure of less than 30 psi, at which point

the valve is designed to be fully open.

4.2.3 Thermal/Electronic Probe/Operating/Safety Controls: Electronic probe-type controls

are also common. This device uses an electrode placed in water.

4.3.0 Expansion/Compression Tanks: An expansion tank, also called a compression tank, is

used to maintain system pressures.

These tanks are normally installed near the boiler.


Section Highlight

4.4.0 System Air Control Devices

4.5.0 Circulating Pumps: On larger systems with high pump head, it is recommended that the

pump(s) be installed in the supply side … discharging away from the boiler and

expansion tank.

4.6.0 Valves

4.6.1 Gate, Ball, Globe, and Angle Valves: Gate valves are used to turn on or shut off the

flow of water or steam.

4.7.0 Heating System Terminals

4.7.1 Convectors: A convector is a heating device that depends mainly on gravity conductive

heat transfer.

5.0.0 Water Piping Systems

5.1.0 One-Pipe Systems: One pipe water systems are used primarily for hot-water heating

systems.

5.2.0 Two-Pipe Systems: Two-pipe systems are classified as either direct-return or reverse

return systems.

5.3.0 Hot Water Zoning

Figure 40 – Boiler piping zoned with valves

7.0.0 Water Balance

7.1.1 System Rate of Flow and Pump Selection

03206-07 Alternating Current

2.0.0 Transformers: The transformer is the key component in an AC-powered system. A

transformer generally consists of two or more coils … and is called the secondary

winding.

The output voltage of a transformer can be calculated by comparing the number of turns

of wire in the primary winding to the number of … This relationship is stated by the

formula: (Formula).

Figure 3 – Multiple-tap secondary winding

Figure 4 – Multiple-tap primary winding


Section Highlight

2.3.0 Transformer Selection: Transformers are rated or sized according to the amount of

power the secondary … expressed in VA (voltage times amperage).

Figure 5 – Three-phase transformers

3.1.0 Sine Wave Generation

Figure 8 – Sine Wave Generation

Because the amplitude of the voltage wave-form varies between zero and peak … volts

produces a working voltage of 120 volts. (equation)

If you know the effective voltage and want to determine the peak voltage …which is the

square root of 2.

3.2.0 Frequency: The speed at which an armature rotates affects the frequency … so does the

frequency.

Figure 9 – Sine wave plot

3.3.0 Single-Phase Power: Power generated at the power station is transmitted as a very high

AC voltage … of a residence is usually about 240 volts.

An Edison hookup is a common wiring arrangement for a power transformer that delivers

power to a residence.

Figure 12 – Edison hookup

Figure 14 – 240V Branch circuits

Figure 15 – 120V Branch circuits

4.1.0 Resistive Circuits: The amount of power consumed by the load is determined by the

formula: P (power) = E (voltage) x I (current).

Figure 22 – Resistive circuit

4.2.0 Inductive Circuits: In a purely inductive circuit, the current waveform will lag the

voltage waveform by 90 degrees.

4.3.0 Capacitors: A capacitor is an electrical storage device that charges and discharges as the

applied voltage changes.

In a purely capacitive circuit, voltage lags the current by 90 degrees.

There are two common types of capacitors … be damaged if it is left in the circuit.


Section Highlight

5.0.0 Induction Motors: AC induction motors are the primary load devices in HVAC

equipment.

5.1.0 Single-Phase Motors: The main components of a single-phase motor are the rotor and

the stator. The stator is fixed and the rotor turns.

5.1.1 Split-Phase Motors: In the split-phase motor an additional winding (Start winding) is

added to the stator … run winding which has fewer turns of the wire.

Split phase motors are used in pumps, oil burners, and other applications requiring 1/3

horsepower or less.

5.1.3 Capacitor-Start Motors: Their high starting torque makes them suitable for powering

and some refrigeration compressors.

5.1.4 Capacitor-Start, Capacitor-Run Motor: The capacitor-start, capacitor-run motor

(Figure 33) is used to drive refrigerant compressors.

5.1.5 Shaded-Pole Motor: Shaded-pole motors are used to drive small fans and pumps.

5.1.6 Multi-Speed Motors: The maximum speed at which a motor can run is known as its

synchronous speed.

5.2.0 Three-Phase Motors: Three-phase motors offer several important advantages over

single-phase motors: (4 bullets).

6.0.0 Testing AC Components

6.3.0 Megohmmeter (megger): Test voltages ranging from 50V to 5,000 V can be supplied by

the megohmeter, or meggar … There are three types of meggers: hand, battery, and

electric.

6.3.1 Safety Precautions: (4 bullets)

6.5.0 Checking Inductive Loads: The start winding of a single-phase motor will have a higher

resistance than the run winding, perhaps three to four times higher.

7.0.0 Safety: Practically all electric shocks are due to human error, rather than equipment

failure … all defects found by tests and inspections.

03208-07 Introduction to Control Circuit Troubleshooting:

2.1.0 Principles of Operation: Most residential and small commercial thermostats are of low

voltage (24 V) type … electrical shock and less chance of fire from short circuits.


Section Highlight

2.2.0 Heating-Only Thermostats: To avoid the discomfort that this condition might cause, the

thermostat … space reaches the setpoint.

2.3.0 Cooling-Only Thermostats: Cooling thermostats contain a device called a cooling

compensator … has a much higher resistance that the switch contacts.

2.5.0 Heating-Cooling Automatic Changeover Thermostats: A thermostat contains a built-

in mechanical differential, which is the cut-in and cut-out points of a thermostat. The

differential is normally 2 F.

2.7.0 Programmable Thermostats: The following are some of the features available on

electronic thermostats:

- Better temperature control

- Installation versatility

- Override control

- Multiple programs

- Staggered startup for multi-unit systems

- Maintenance tracking

2.9.0 Thermostat Installation

2.9.1 Installation Guidelines: The thermostat should be installed in the space in which it will

be called upon to control the temperature … making the thermostat contacts chatter.

2.9.2 Thermostat Wiring

2.9.3 Checking Current Draw: The current draw is usually printed on the furnace nameplate

… R and W terminals of the existing wall plate or sub-base.

3.1.0 Relays, Contactors, and Starters

3.1.1 Relays: A relay operates to stop or permit the flow of electricity.

3.1.3 Contactors and Starters: A motor starter is used to stop and start motors and provide

overload protection.

3.3.0 Lockout Control Circuit: The purpose of the lockout relay in a control circuit is to

prevent the automatic restart of the HVAC equipment.

3.5.0 Compressor Short-Cycle Timer: A compressor short-cycle protection circuit contains a

timing function that prevents the compressor … Lockout periods are typically 2 to 5

minutes.

3.7.2 Limit Control

Figure 34 – Circuit diagram of a cooling / gas heating system


Section Highlight

5.1.0 Customer Interviews: Talking to the customer prior to working on the equipment

is always valuable information on equipment … thereby eliminating unnecessary

equipment maintenance.

5.4.0 Use of Manufacturer’s Troubleshooting Aids

5.4.1 Label Diagrams: They normally show a component arrangement diagram, wiring

diagram, legend, and notes pertaining to the equipment.

5.4.3 Diagnostic Equipment and Tests

Figure 35 – Typical label diagram

6.0.0 Safety

6.1.0 Safety Practices: The following is a list of recommended safety practices: (8 bullets).

7.0.0 HVAC System Troubleshooting

8.0.0 HVAC Equipment Input Power, Load, and Control Circuits: Most HVAC

equipment can be divided into three functional circuit areas: (3 bullets).

10.3.0 Start Relay Checks: When the start relay is operating properly, the clamp-on ammeter

current indication should momentarily … is good because its contacts have opened.

10.5.0 Identifying Unmarked Terminals of a PSC/CSR Motor: First, the multimeter is used

to find the two terminals across

Figure 57 – Identifying unmarked terminals of a PSC/CSR motor.

12.0.0 Pneumatic Controls

12.1.0 Basic Components: P-E relays are simply pressure switches in which a pneumatic signal

causes an electrical change … switch differentials (the pressure change that causes the

switch to make and break).

13.0.0 HVAC Digital Control Systems

13.1.0 Direct Digital Control

Controlling Devices

03209-07 Troubleshooting Gas Heating


Section Highlight

2.1.0 Natural-Draft Packaged Units: Government-mandated energy efficiency requirements

for gas furnaces cannot easily be met with furnaces using natural draft venting

technology.

Figure 1 – Natural Draft Gas Heating System

The basic operating sequence of any natural-draft unit is as follows: 1-5.

Induced-Draft Packaged Units

Figure 3 – Induced-draft gas heat/electric cool unit

2.3.0 Induced-Draft Gas Furnace

2.5.0 Low-and High-Intensity Infrared Gas-Fired Heaters: The basic purpose is to heat

objects, not air.

2.5.1 Low-Intensity Infrared Gas-Fired Heaters: Tubular heaters are available in either

vented or non-vented versions…by a blower in the burner assembly at the input to the

tube.

2.5.2 High-Intensity Infrared Gas-Fired Heaters: These non-vented units also called direct-

fired radiant burners, are used at high levels off the floor as spot or space heaters.

In some cases, the grids can also be closely covered by an optional wire screen, called

reverberator, that increases the infrared radiation when heated.

3.1.0 Troubleshooting Thermocouples: A thermocouple generates only enough voltage to

hold open the safety valve once … but operate at 18 to 25 millivolts under load.

3.2.0 Troubleshooting Pilot Resignation and Direct Ignition Devices: Pilotless systems uae

either a hot surface ignitor (HIS), which is made of ceramic material that glows when a

current flows through it, or a direct spark ignitor. Both ignite the gas at the burner.

3.2.1 Spark Ignitors: If there is no spark at all, the spark gap … is most likely in the ignition

module or the high-voltage wire to the ignitor.

3.2.2 Glow Coil Ignitors: A glow coil of platinum wire to ignite the pilot gas … so the voltage

drop across the glow coil is 11.5 to 12 volts.

3.3.0 Troubleshooting the Flame Sensor: The normal range is between 0.5 and 4.5

microamperes.

3.3.1 Testing a Combined HIS/Flame Sensor: The meter used must have a DC

microammeter range of about 10 microamps.


Section Highlight

4.0.0 Air System: In addition to component failure, there are three general kinds of problems

that can occur in the supply and return system:

- Obstructed air flow

- Ductwork

- Blower motor

03212-07 Basic Installation and Maintenance Practices

2.1.1 Thread Designations: The three series are:

- Unified National Course

- Unified National Fine

- Unified National Extra Fine

2.1.2 Fastener Grade Designations

Figure 1 – Thread Designations

2.2.0 Types of threaded fasteners include the following:

- Set screws

- Machine bolts

- Flat and lock washers

- Nuts

- Thread-forming and thread-cutting screws

- Toggle and anchor bolts

- Inserts

2.2.1 Machine Bolts, machine Screws, Stud Bolts, and Cap Screws:

Machine bolts are used to assemble parts that do not require close tolerances.

Machine screws are used for general assembly.

Cap screws are generally used on assemblies that need a finished appearance.

Stud bolts are headless bolts, threaded either along the entire length or on both ends.

2.2.2 Set Screws: They are used to fasten pulleys and fan blades on shafts, and to hold collars

in place.

2.2.3 Flat and Lock Washers: Some common types of lock washers include the following:

- External

- Internal

- Internal-external

- Countersink

- Split ring


Section Highlight

2.2.4 Nuts: Some special-purpose nuts include the following:

- Acorn nut

- Castellated (or castle) and slotted nuts

- Self-locking nut

- Wing nut

- Jam nut

- U-nuts and J-nuts

- Cage nut

2.2.5 Thread-Forming and Thread-Cutting Screws: Thread-forming screws are used mainly

to fasten light-gauge metal parts.

2.2.6 Toggle and Anchor Bolts: Toggle bolts are used to fasten a part to a hallow wall or

panel.

2.3.0 Non-Threaded Fasteners: This section describes the following types of non-threaded

fasteners:

- Retainer rings

- Pins

- Keys

- Rivets

2.3.2 Pins: Some common pins and their uses are as follows:

- Dowel pins

- Taper and spring pins

- Cotter pins

2.4.0 Installing Threaded Fasteners

2.4.1 Torqueing Steel Fasteners: When torqueing steel fasteners, you must first select the

proper type … to the recommended specifications.

Figure 14 – Torque Specifications

Torque is the resistance to turning or twisting force … the scale when the required torque

is applied.

The following terms, sometimes used in manufacturer’s service literature must be

understood when using a torque wrench:

- Break-away torque

- Set or seizure

- Run-down resistance

2.4.2 Flange Tightening Sequences: When tightening bolts on flanges and similar surfaces,

the bolts … in the fastener type, then tighten to the final torque.


Section Highlight

2.4.4 Installing Anchor Bolts: When installing a non-expansion anchor bolt in hardened

concrete, it is installed … Also, the anchor bolt should extend out of the hole far enough

for the threads and a little of the unthreaded bolt to be above the surface level.

3.0.0 Gaskets: The basic function of a gasket is to create a seal between two fixed parts … and

compressor cylinder heads.

3.2.0 Installing and Removing Gaskets: When installing the new gasket, do not over tighten

the bolts because … should not be used with the gaskets unless specified by the

manufacturer.

5.0.0 Seals: Seals are devices used to prevent or control leakage between moving and fixed

parts … non-mechanical and mechanical.

5.1.0 Nonmechanical Seals: Nonmechanical seals are used both as static seals and dynamic

seals … Lip and oil-type seals are examples of seals used as dynamic seals.

5.1.1 O-Rings: O-rings are circular seals used as either static or dynamic seals.

5.1.2 Lip and Oil Seals: Lip seals are low pressure, positive-contact seals used with rotating

shafts.

6.0.0 Bearings: The following terms are commonly used when describing the operation of

bearings:

- Axial Load

- Journal

- Radial Load

- Thrust

6.1.0 Plain Bearings: Plain bearings are simple in construction, operate efficiently, and can

support heavy loads.

6.2.0 Anti-Friction Bearings: Anti-friction bearings are so named because they operate on the

principle of rolling motion, using either balls or rollers between rotating and fixed

surfaces.

6.2.1 Ball Bearings

6.2.2 Roller Bearings

6.4.0 Removing and Installing Bearings

6.4.2 Installing Bearings: The temperature mounting method used for interference bearings

can usually be performed … the bearing is still in the equipment.


Section Highlight

When using this method, care must be taken not to overheat the bearing … The

maximum temperature to which a bearing should be heated is 250 F.

7.1.0 Oils

7.1.1 Viscosity: Viscosity is the thickness of a liquid or the ability of the liquid to flow at a

specific temperature.

7.2.0 Greases: Grease is not a liquid and cannot form a liquid film when it is initially applied

… grease releases some of its oil, allowing the lubrication action to begin.

8.0.0 Belts and Belt Drives

8.1.0 V-Belts

8.1.1 Fractional Horsepower Belts: Fractional horsepower (FHP) belts are light-duty belts,

usually used singularly.

FHP belts come in the following standard widths and heights: 2L, 3L, 4L, 5L

8.1.2 Standard Multiple Belts: Standard multiple belts are used for continuous service.

They are available in various lengths for each width size and in the following standard

widths and heights: A, B, C, D

8.1.3 Wedge Belts: The wedge belt is a multiple belt that has a smaller cross-section per

horsepower than the standard widths and heights: 3V, 5V, 8V

9.0.0 Couplings and Direct Drives

9.1.0 Coupling Types

9.1.1 Rigid Couplings: Rigid couplings provide a nonflexible connection between the driver

and driven shafts.

9.1.2 Flexible Couplings: Flexible couplings are much more common than rigid couplings

because they are usually easier to install and maintain and do not require precise

alignment.

9.1.3 Soft-Start Couplings: Soft-start couplings are used in applications where smooth, even

starts are needed.

9.3.0 Coupling Alignment: When aligning two coupling halves so that the shafts will be

aligned … This results in four basic ways the coupling must be aligned. (4 bullets).


Section Highlight

9.3.1 Correcting Outer Diameter Alignment, Side View: In OD misalignment, one coupling

is higher than the other, and one of the units must be raised or lowered to align the

couplings.

9.3.2 Correcting Outer Diameter Alignment, Top View: In this type of misalignment, one of

the units must be moved to one side or the other to align the couplings.

9.3.3 Correcting Face Alignment, Side View: In this type of misalignment, one of the units

must be tilted on its base to align the couplings.

9.3.4 Correcting Face Alignment, Top View: In this type of misalignment, one of the units

must be rotated on its base to align the couplings.

10.0.0 Basic Maintenance Procedures

10.1.0 Measuring Devices

10.1.2 Calipers and Dividers: Calipers are used to measure the thickness or diameter of a piece

of work … compare and transfer work dimensions.

10.2.0 Supplemental Tools

10.3.0 General Guidelines for the Care and safe Use of Hand and Power Tools

10.4.0 Motor Lubrication: The most common problem with lubricating motor bearings is

over-lubrication. It can cause and increase in operating temperature and a decrease in

viscosity.

11.0.0 Documentation

11.2.0 Service Ticket/Invoice: At the completion of the service call, the technician fills in all

applicable portions of the form to provide a specific description of the work that … the

labor hours expended, and so on.

11.3.0 Commissioning Job Report: At the completion of most large commercial and industrial

HVAC installations, a commissioning process is used to document and verify … with the

design intent.

At the completion of the process, these checklists and reports are turned over to the

building owner or other designated authority.

11.4.0 Start-up Report: Forms are used to record a specific operating conditions and

parameters that exist at the time … or individual components of an HVAC system.

11.5.0 Warranty Ticket: HVAC equipment warranty forms or tickets should be filled out and

given to manufacturers to notify them that their equipment has been put into operation.


Section Highlight

12.0.0 Customer Relations

12.2.0 Personal Habits, Behaviors, and Attitudes: The customer’s first glimpse of a

technician can determine that the customer’s opinion of the worker and the company the

technician represents.

12.3.0 Customer Relations: Handling Service Calls: The typical service call has three parts:

- The opening

- Servicing

- The closing

13.0.0 Customer Communication: Here are some simple yet effective tips: (4 bullets).

13.3.0 Showing Concern for Customers: Do this by:

- Being a good listener

- Talking in terms of the customer’s interests

- Keeping your personal problems to yourself

- Answering questions honestly, but positively

- Respecting your customers opinions

- Not socializing while on the call

13.4.0 Handling Difficult Customers

03301-08 Refrigerant Characteristics: In order to be: (5 bullets)

1.3.0 Common Refrigerant Applications: Different refrigerants are used in different

refrigerants available:

- HCFC-22

- HFC-410A

- HFC-407C

- HCFC-123

- HFC-404A

- HFC-134a

Table 1 Common Refrigerants

2.1.0 Refrigerants Classifications: Refrigerants fall into the following three major

classifications of halocarbons:

- Chlorofluorocarbons (CFCs)

- Hydrogentated chlorofluorocarbons (HCFCs)

- Hydrogentated fluorocarbons (HFCs)

2.1.1 CFC Refrigerants: Chlorofluorocarbon (CFC) refrigerants are the most damaging to the

environment because they contain more chlorine atoms in their structure.


Section Highlight

2.1.2 HCFC Refrigerants: Hydrogenated chlorofluorocarbon (HCFC) refrigerants contain

chlorine …. Allowing them to be phased out over a longer period of time.

2.1.3 HFC Refrigerants: Hydrogenated fluorocarbon (HFC) refrigerants such as HFC-123

contain no chlorine atoms in … of the three classifications of halocarbon refrigerants.

2.3.0 Refrigerants and the Environment – Ozone Depletion: Refrigerants are listed

according to their ozone depletion potential (ODP). The lower the number, the lower the

ozone depletion potential.

Table 2: Ozone Depletion Potential of Refrigerants

3.0.0 Refrigerant Identification: (4 bullets)

3.1.0 Refrigerant Safety Classifications:

Table 3 Old Versus New Refrigerants

- Class I

- Class II

- Class III

- Class IV

3.1.1 Refrigerant Cylinder Identification

Table 4 Refrigerant Cylinder Color Codes

3.2.0 Refrigerant Cylinder Safety: Disposable cylinders are single-use cylinders.

Returnable/reusable cylinders are to be returned to the distributor and/or refrigerant

manufacturer for refilling after they become empty.

Recovery cylinders are special cylinders designed for use with refrigerant recovery

machines.

Generally, the maximum capacity of a recovery cylinder is 80 percent of the cylinder’s

gross weight (weight of cylinder and refrigerant).

4.0.0 Refrigerant Composition

4.1.0 Azeotropes

4.2.0 Zeotropes: A zeotropic blend never mixes chemically … and finishes condensing

(bubble point) when heat is removed from the refrigerant.


Section Highlight

Figure 9: P-T chart for azeotropes

4.4.0 Using Pressure-Temperature (P-T) Charts: A pressure-temperature (P-T) chart shows

the pressure and temperature relationships at saturation for a specific refrigerant.

4.4.1 Calculating Superheat: Step 1 -4.

4.4.2 Calculating Subcooling: Step 1 -4.

5.0.0 Refrigerant Leaks

5.1.0 Finding Leaks: The following are some common leak sites: 4 bullets.

5.2.0 Isolating Leaks: Some of the uncommon methods used to isolate leaks include:

- Leak-detecting fluids

- Halide torch

- Leak-detecting dyes

- Electronic leak detectors

5.2.1 Pressurizing for Leak Detection: Use the following procedure to pressurize a system:

Step 1 -4. Step 4: If a leak detecting fluid is being used … No refrigerant is needed.

6.0.0 Lubricating Oils

6.1.0 Lubricating Oil Properties

6.1.1 Stability

6.1.2 Viscosity: Viscosity can be described as the resistance of a fluid to flow.

6.1.3 Pour Point: It can be defined as the temperature at which oil first starts to flow.

6.1.4 Dielectric Strength: Dielectric strength is the ability of oil or any material to resist

breaking down in the presence of voltage.

6.1.5 Floc Point: The floc point of oil is the temperature at which heated oil vapors burst into

flame.

6.1.6 Flash Point: The flash point of oil is the temperature at which heated oil vapors burst

into flame.

6.1.7 Material Compatibility

6.1.8 Foaming: caused by mechanical movement in the compressor and/or dissolved

refrigerant boiling … leading to mechanical wear or failure of the compressor.


Section Highlight

6.2.0 Oil Types

6.2.1 Mineral Oils: Mineral oils have traditionally been used in the systems using CFC and

HFC refrigerants.

6.2.2 Synthetic Oils: the predominant synthetic oils are gycol-, ester-, ether-, or alklbenzene-

based.

Polyalkylene glycol (PAG) oil is widely used in automotive air conditioning systems

where HFC-134a is the refrigerant.

Polyolester (POE) oil is very compatible with most of the newer HFC refrigerants and is

widely used in those applications.

Polyvinyl ether (PVE) oil has properties similar to mineral oils but can be used with

HFC refrigerants.

Refrigerant compatibility with various refrigerant oils varies … and oil are best suited for

the application.

Table 5: Refrigerants and Oils

7.1.0 Refrigeration System Piping: During cold starts, the refrigerant/oil mixture in the

crankcase can foam are refrigerant boils … piping sections called risers.

7.2.0 Refrigeration System Contamination: Ideally, the only two substances that should be

inside a refrigeration system are refrigerant … and solid contaminants such as metal

particles.

8.0.0 Oil Handling Guidelines

8.1.0 Personal Protective Equipment: When handling refrigerant oils, wear oil resistant

gloves and eye protection.

8.2.0 Working with Oils: When working with synthetic oils, follow these guidelines:

(7 bullets).

9.0.0 System Conversion: With CFC and HCFC refrigerants being phased out, refrigerant

manufacturers have developed replacement refrigerants … less environmentally

damaging refrigerants.


Section Highlight

9.1.0 Common Refrigerant Conversions: There are a variety of refrigerants available for

retrofitting systems from CFC and HCFC refrigerants to more environmentally friendly

refrigerants. Some of the more common ones include the following:

- CRC-11 retrofits

- CFC-12 retrofits

- HCFC-22 retrofits

HFC-410A is considered to be likely replacement refrigerant for HCFC-22 …. of its

much higher operating pressures.

03304-08 Retail Refrigeration Systems

2.0.0 Mechanical Refrigeration Systems

Figure 1 Basic Refrigeration System

Refrigeration applications are generally classified based on the required space

temperature for a given application … classified for duty based on these temperature

ranges:

- Above +60 F

- - 30F to +60 F

- - 40 F to -30 F

2.1.1 Medium-Temperature Refrigeration Cycle: Refer to Figure 2 for an example of a

typical medium-temperature refrigeration cycle using HFC-134a as the refrigerant.

Figure 2: Typical medium-temperature refrigeration cycle for HFC-134a

2.1.2 Low Temperature Refrigeration Cycle: Figure 3 represents a typical low-temperature

refrigeration circuit, such as that used in a reach-in freezer.

2.2.0 Primary Refrigeration Cycle Components

2.2.1 Compressors: Discharge line thermostats will also be incorporated into the controls to

further prevent compressor damage or failure from overheating. They are generally set to

open at 250F to 260 F.

2.2.2 Condensers: Regular condenser cleaning must be an integral part of retail refrigeration

systems maintenance.

2.2.3 Evaporators: Forced-draft, finned-tube evaporators are most commonly used in smaller

retail refrigeration fixtures and systems …. referred to as unit coolers, or unitary coolers.

Some units may also use the condensate to their advantage … The moisture is evaporated

back to the surrounding environment in the process.


Section Highlight

To minimize dehydration of the product and maintain higher humidity levels, evaporator

coils … desired storage temperature and the refrigerant.

Unitary evaporator coils that operate at 30 F and below generally form frost and will

require some automated means of frost removal.

2.2.4 Expansion Metering Devices: The expansion device controls the flow of refrigerant into

the evaporator, performing the following two primary functions: (2 bullets).

2.3.0 Other Refrigeration Circuit Devices and Components

2.3.1 Receivers: Receivers are used only on systems with a TXV or other modulating metering

device.

2.3.2 Accumulators: The accumulator is basically a trap designed to capture liquid refrigerant

in the system suction line.

2.3.3 Crankcase Pressure Regulators: Crankcase pressure regulating (CPR) valves are

installed in the suction line just upstream of the compressor, as shown in Figure 13.

2.3.4 Evaporator Pressure Regulating Valves: The evaporator pressure regulating (EPR)

valve allows the evaporators serving the higher temperature areas to maintain proper

refrigerant … temperature of the refrigerant.

2.3.5 Refrigerant-Side Head Pressure Control: Refrigeration units installed in locations

subject to low ambient temperatures generally require a method of maintaining head

pressure … device may not be sufficient to ensure adequate refrigerant is fed to the

evaporator.

The most accurate and stable means of ensuring that an adequate head pressure is

maintained is by using a head pressure control valve.

3.0.0 Defrost Systems: In retail refrigeration applications, these are four primary defrost

methods:

- Off-cycle defrost

- Timed defrost

- Electric defrost

- Hot-gas defrost

3.1.0 Off Cycle-Defrost: Off cycle defrost is the simplest and most passive of the defrost

approaches … during the normal off cycle.

3.2.0 Timed Defrost: Systems that operate at slightly lower temperatures than those using

simple off-cycle defrost will require a longer … 32 F to 36 F often benefit from this

approach.


Section Highlight

3.3.0 Electric Defrost: Electric defrost systems are prevalent for medium … in the retail

refrigeration class.

3.4.0 Hot-gas Defrost: Hot-gas defrost sends discharge gas from the compressor directly to the

evaporator, bypassing the metering device through the use of several solenoid valves.

4.0.0 Retail Refrigeration Equipment and Fixtures

4.1.0 Ice Merchandisers: Ice merchandisers are generally offered with two major options –

cold wall construction, which offers no automatic defrost function … and allowing it to

warm to ambient temperature.

4.2.0 Reach-In Coolers and Freezers: Medium-temperature units may incorporate either off-

cycle or timed defrost …. Units using HCFC-22, HFC-134a, or HFC-404A as a

refrigerant dominate the market at this time.

4.4.0 Commercial Ice Markers

4.4.1 Cubed-Ice Machines: Cubed-ice machines have four basic modes of operation: fill,

freeze, harvest, and drain-down.

An ice thickness sensor is typically used on a cubed-ice evaporator … reached proper

thickness, the harvest mode is initiated.

5.0.0 Common Refrigeration System Controls

5.1.0 Thermostats: Electronic temperature controls are also becoming very popular in the

industry … an 8-foot cooper or aluminum capillary tube through complex cabinet

components.

5.2.0 Pressure Controls: Pressure controls, sometimes called pressurestats, are also applied to

refrigeration systems in many different ways.

The following are some of the functions that pressure switches provide: (6 bullets).

5.3.0 Time Delay Relays: Time delay are used to delay a switching action or ensure that a

sequence of actions takes place at the proper time.

Most of the time delay relays used in refrigeration applications can be specified as one of

the following types:

- Delay-on make

- Delay-on-break

- Bypass duty


Section Highlight

5.4.0 Solenoid Valves: Solenoid valves are used to stop or allow the flow of either liquids or

gases in refrigeration systems.

The following are some of the applications for solenoid valves: (4 bullets).

6.0.0 Troubleshooting

6.1.0 Troubleshooting and Maintenance of a Reach-In Freezer

Figure 40 Troubleshooting chart

6.2.0 Troubleshooting and Maintenance of Cubed-Ice Machines

Figure 42 Energized parts chart

3305-08 Commercial Hydronic Systems

1.0.0 Introduction: Hydronic systems provide several advantages over forced-air systems in

the commercial environment … medium must be transported, the more economy

hydronic systems offer.

2.0.0 Water Concept Review

2.1.0 Water: At sea level, water boils at 212 F and freezes at 32 F.

2.2.0 Water Pressure

2.3.0 Pressure Drop: Defined as the difference in pressure between two points, pressure drop

is an important factor in all hydronic systems.

The change in pressure drop resulting from a change in flow in gallons per minute (gpm)

can be calculated as follows: (Equation).

This information may be expressed in a variety of units, so the conversions below may be

helpful: (4 bullets).

2.4.0 Head Pressure: Head pressure is another measure of pressure, expressed in feet of water

…. simple calculations prove that a column of water 2.31 feet in height results in a

pressure of 1 psi.

Figure 1 Water pressure concepts

Figure 2 Relationship of head pressure in feet to pounds per square inch

3.0.0 Commercial Hot-Water Heating System Components


Section Highlight

3.1.0 Commercial Hot-Water Boilers

Low-pressure hot water boilers can be built to have working pressures of up to 160 psi.

Low-pressure hot water boilers are limited to a maximum operating temperature of 250 F.

3.1.1 Copper-Finned Tube Boilers: With the copper-finned tube design, heat transfer is

greatly enhanced, providing for rapid recovery and eliminating the need for hot water to

be stored within the boiler itself.

3.1.2 Cast-Iron Boilers: cast-iron boilers are formed by assembling individual cast-iron …

The number of sections used determines the size of the oiler and its energy rating.

3.1.3 Steel Firetube and Watertube Boilers: Two types of steel boilers are the firetube boiler

and the watertube boiler … with the flue gases on the outside.

3.1.4 Steel Vertical Tubeless Boilers: In this boiler, the water vessel surrounds the

combustion chamber … the length of the furnace.

3.1.5 Electric Boilers: electric boilers use immersion resistance heater elements to heat the

water in the boiler. Heating results from the electrical current flowing through the heater

elements.

Boiler operation is controlled by an electric/electronic controller.

Another type of electric boiler, called an electrode boiler, relies … the amount of water

that comes in contact with the electrodes.

3.2.0 Boiler Operating/Safety Controls: Float operated; low-water fuel cutoff controls can

be used to protect boilers from damage … related electrical switch.

Copper-finned tube style units transfer heat effectively with no significant volume of

water contained on board … copper-finned tube units should be equipped with water

flow switches.

3.4.0 Air Management: Due to the greater volume of water and the potential for much larger

volumes of air to collect and create problems … equipped with an air separator, such that

shown in Figure 14.

This particular unit, available in sizes large enough to accommodate 36” pipe …. At

which the buoyancy of the air bubbles cause them to rise and they are no longer swept

along by the water stream.

3.5.0 Circulating Pumps


Section Highlight

3.5.1 Centrifugal Pump Construction: A centrifugal pump operates by increasing the

velocity of a liquid.

Centrifugal pump parts, as shown in Figure 18, include the following primary parts:

- Pump casing

- Suction port

- Discharge port

- Pump shaft

- Bearings

- Impeller

- Impeller vanes or blades

- Impeller shrouds

- Wearing rings

- Packing gland

- Mechanical seal

Figure 18 Centrifugal pump components

3.6.0 Valves

3.6.1 Multi-purpose Valves: In larger systems, a multi-purpose valve is commonly installed in

the discharge side of the circulating pump.

3.6.3 Butterfly Valves: A butterfly valve has a round disc that fits tightly in its mating seat and

rotates 90 degrees in one direction to open and allow fluid to pass through the valve.

There are three common types of butterfly valves in use:

- Wafer-type

- Wafer lug

- Two-flange

3.6.4 Two-Way and Three-Way Valves: Two and three-way valves are used to control the

flow and/or temperature of hot water, chilled, water, or both.

3.7.0 Heating System Terminals: The following types of terminals are commonly used in

heating-only systems:

- Convectors

- Baseboard and finned-tube units

- Unit heaters, unit ventilators, and fan coils

- Heating coils

4.0.0 Chilled-Water Cooling Systems: The use of a chilled-water system eliminates the need

to circulate refrigerant through refrigeration system components installed in a building to

provide comfort cooling.


Section Highlight

The chilled water produced is described as a secondary coolant, which is any liquid that

is cooled by a system refrigerant and is then used to transmit heat from the conditioned

space without a change in state.

5.0.0 Chilled-water System Components

5.1.0 Water Chillers: Water chillers fall into two classes: mechanical and nonmechanical.

Mechanical chillers use compressors to provide cooling.

Nonmechanical chillers do not have a compressor …This type of chiller is called an

absorption liquid chiller.

Three common types of mechanical chillers are reciprocating or scroll compressor liquid

chillers, centrifugal chillers, and screw liquid chillers.

5.1.1 Reciprocating and Scroll Liquid Chillers

5.1.2 Centrifugal Liquid Chillers: Purge units are another type of device used on centrifugal

chillers that operate with low-pressure refrigerants, such as HCFC-123 … A purge unit

must be used to remove the noncondensible gases and water vapor from the system.

5.1.3 Screw Liquid Chillers

5.1.4 Absorption Liquid Chillers

5.2.0 Chiller Operating/Safety Controls

5.3.0 Cooling Towers/Evaporative Condensers: Condensers are used to remove heat from

the chiller refrigerant system.

5.3.1 Cooling Towers

5.3.2 Evaporative Condensers: The evaporative condenser combines the functions of a water-

cooled condenser and cooling tower … removing about 1,000 Btu’s from refrigerant

flowing through the tubes.

5.4.0 Circulating Pumps

5.5.1 Fan Coil Units: Fan coil units are terminals that can be used for chilled-water cooling

only, or for both cooling and heating … and sometimes an outside air connection with a

manual damper.

The term fan coil unit generally refers to units that produce up to 2,000 cfm of airflow.

6.0.0 Dual-Temperature Water Systems


Section Highlight

7.0.0 Commercial Water Piping Systems

7.4.0 Primary-Secondary Water Systems: Primary-Secondary hot water or chilled water

systems are used in applications that have peak and varying loads.

Figure 55 Simplified primary-secondary chilled water system

8.0.0 Water System Balancing

03306-08 Steam Systems

2.0.0 Fundamentals and Properties of Water: Sensible heat is heat that can be sensed by a

thermometer or touch.

Latent heat is the heat energy absorbed or rejected when a substance is changing state

without a change in the measured temperature.

It requires 144 Btus of latent heat to melt the pound of ice before the temperature began

to rise. This is 144 times as much heat as is needed to raise the temperature of water one

degree (specific heat).

- Latent heat of fusion

- Latent heat of vaporization

- Latent heat of condensation

- Superheat

- Subcooling

Figure 2 Change of State Terminology

3.0.0 Steam Cycle Principles of Operation: Steam traps are among the most important

devices used in the steam cycle … Traps also require the most attention and maintenance

to ensure their proper operation, because failure of a steam trap can create a number of

problems.

4.0.0 Steam Boilers, Boiler Controls, and Accessories

4.1.0 Steam Boilers: Steam boilers are divided into three broad categories; those that produce

low-pressure steam; those that produce medium-pressure steam; and those that produce

high-pressure steam … High-pressure boilers operate at pressures from 60 psi and up.

With the exceptions that follow, steam boilers operate in the same manner as hot-water

boilers: (3 bullets).

4.2.0 Boiler Operating/Safety Controls


Section Highlight

4.2.1 Pressure Gauge: This gauge is installed at the highest point of the boiler’s steam space.

A siphon assembly is generally installed between the boiler and the gauge.

4.2.2 Water Gauge Glass/Water Column: The water gauge glass is used to check the water

or steam level in the boiler.

4.2.3 Low- and High-Water Cutoff and water Feeder Controls: Low-water cutoff controls

provide valuable protection for steam boilers by interrupting power to the heat source

when the water falls below the minimum safe level.

4.2.4 High-Pressure Limit and Other Controls: The high-pressure limit control, also known

as pressuretrol, is activated by a rise in boiler pressure.

4.2.5 Pressure (Safety) Relief Valve: A pressure (safety) relief valve is used to protect the

boiler and the system from steam pressures exceeding the pressure rating of the boiler or

the system.

5.0.0 Valves

6.0.0 Heat Exchangers/Converters: A heat exchanger is used to transfer heat from on

medium to another.

For added safety against contamination, most heat exchangers used to heat potable water

are of double-walled construction … required if conditioning chemicals have been added

to the steam system.

8.1.0 Mechanical Steam Traps: Mechanical steam traps respond to the difference in density

between steam and steam condensate.

8.2.0 Thermostatic Steam Traps: Thermostatic steam traps respond to temperature changes

in the steam line.

8.3.0 Thermodynamic Steam Traps: Thermodynamic steam traps use the heat energy in hot

condensate and steam to control the opening and closing of the trap.

8.4.0 Fixed-Orifice Steam Traps

8.5.0 Installing a Steam Trap: Two generally rules for steam-trap mountings are that they

should be lower than any line in the system, and that a strainer has to be upstream of the

trap.

The following is a list of general guidelines for proper steam-trap installation: (12

bullets). #12: When a bypass is necessary, a globe valve should be used to allow manual

balancing of condensate flow.


Section Highlight

8.6.0 Maintaining Steam Traps

8.6.4 Bimetal Thermostatic Trap

9.0.0 Troubleshooting Steam Traps

9.1.0 Diagnostic Methods: Three basic diagnostic methods of reading a steam system are

sight, sound, and temperature. The criteria observed include pressure.

10.1.0 Condensate Pump and Receiver Tank: The receiver tank is also equipped with a float-

actuated makeup water feeder control … water to enter the receiver tank from the city

water supply.

10.2.0 Vacuum Pumps: Vacuum pump operation is similar to condensate pump operation in

that the vacuum pump … to flow to the receiver tank.

11.0.0 Flash Tanks: When hot condensate under pressure is released to a lower pressure, part of

it is re-evaporated and becomes flash steam.

Some of the condensate flashes into steam and flows along with liquid condensate

through the return lines back to the boiler.

12.0.0 Steam System Piping

12.1.0 One-Pipe Systems: When the return is above the boiler water line, it is called a dry

return … The section of return piping installed below the level of the water in the boiler

is called the wet return.

12.2.0 Two-Pipe Systems: Two-pipe systems can have either gravity or mechanical condensate

returns. However, most systems use a mechanical return.

A vacuum-return system is similar to a condensate return system, except thst s vacuum

pump is installed to provide a low vacuum in the return line to return the condensate to

the boiler.

Operating the return line in a vacuum, rather than at or slightly above at … lowered for

significant fuel savings and improved efficiency.

13.0.0 Steam and Condensate Pipe Sizing: Operating steam boilers at pressures significantly

lower than the boiler is designed for reduces the volume of space in the boiler that

normally … water droplet carryover is greatly increased.

Undersized piping causes high pressure drops and greater velocities increasing noise and

erosion of internal piping surfaces.


Section Highlight

On the other hand, piping that is too large creates unnecessary heat losses and higher

installation costs.

13.1.0 Velocity Sizing: Figure 45 provides a steam velocity chart for pipe sizing.

Figure 45 Steam pipe sizing for steam velocity

13.2.0 Steam Line Pressure Drop: Steam lines are generally sized based on velocity … for

pressure drop in the system.

However, a system operating as low as 5 psig should probably … than 0.3 psig to

maintain the needed pressure downstream.

Figure 46 Steam pipe sizing for pressure drop

13.3.0 Condensate Line Sizing

14.0.0 Boiler Blowdown and Skimming

03308-08 Water Treatment

2.0.0 Water Characteristics and Analysis: Even though the quality of a water supply makes

it safe to drink … water is used untreated in HVAC systems.

The strength or relative amount of an element present in a water solution is commonly

referred to as its concentration … element that is dissolved in a water sample.

The amount of carbon dioxide in water can be either measured directly or estimated from

the water’s pH and total alkalinity… amount of pH reduction from the addition of acids.

Water above the pH value of 7.0 is considered to be alkaline.

The hardness of a water sample indicates the amount of dissolved calcium (limestone)

salts and/or magnesium in the water.

As the hardness level increases, the amount of scaling usually increases … solids are not

visible and consists mainly of calcium, magnesium, chloride, and sulfate.

The greater the concentration, the greater the potential for corrosion … individual

particles or give water a cloudy look.

3.0.0 Problems Caused By Water Using Untreated Water: External corrosion appears as

rust or oxidation. Internal corrosion can be caused by acids, oxygen, and other gases

present in the water.


Section Highlight

3.3.0 Biological Growth: A film composed of bacteria, other organisms, and slimes produced

by the microorganisms acts as an insulator.

4.0.0 Water Treatment in Open Recirculating Water Systems: acidic gases and other

contaminants in the air are absorbed into the water.

The range of pH in cooling tower water is typically maintained between 7.5 and 8.5.

4.3.0 Biological Growths: The water contact with air that occurs in a cooling tower or

evaporative condenser allows …. debris to be introduced into the system recirculating

water.

5.0.0 Water Treatment in Closed Recirculating Water Systems: Oxygen is one of the main

agents of corrosion.

5.1.0 Corrosion: Some localities prohibit the use of chromates, while others allow their use

only in closed systems.

6.0.0 Water Treatment in Steam Boilers and Systems: Fouling clogs nozzles and pipes with

solid materials, thereby restricting circulation and reducing the heat transfer efficiency.

6.1.0 Corrosion: To minimize corrosion, the boiler water pH should be maintained between 11

and 12 by an alkaline water treatment using soda ash.

7.0.0 Mechanical Water Treatment Equipment

7.1.0 Filtration Equipment

7.1.2 Cartridge Filters: They are commonly used to remove suspended particles ranging

between 1 micrometer and 100 micrometers.

Depth-type filters capture particles throughout the thickness of the filtering medium.

Surface-type filters are thin-media made from pleated paper or similar material … and

have a better removal efficiency than an equivalent size depth filter.

7.1.5 Centrifugal Separators: Generally good for removing suspended particles greater than

45 micrometers in size, they tend to be inadequate at removing smaller ones.

7.3.0 Water Softeners: Many water softeners use a sand-like substance called zeolite that is

saturated with sodium … as the supply of hard water filters through the zeolite, sodium is

released and calcium and magnesium are absorbed.

Through extender use, the sodium content of the zeolite bed gradually depletes, thus

preventing the unit from softening the water … periodically treating the unit with a strong

dose of salt solution.


Section Highlight

7.4.0 Deaerators: Dearators (Figure 11) are typically used in steam systems to remove air and

other noncondensible gases from the system feedwater.

8.0.0 General Water Treatment Procedures and Guidelines

03309-08 Troubleshooting Electronic Controls

2.0.0 Microprocessor Controls: Likewise, if a cooling thermostat calls for cooling, you

expect the compressor and fans to turn on. If they don’t, you know that something is

wrong.

3.0.0 Troubleshooting Microprocessor Controlled Systems

3.1.0 Troubleshooting Approach: Another reasonable assumption is that when the thermostat

is calling for heat or cooling, there will be 24V (or other specified voltage) applied to the

control board input.

4.0.0 External Causes of Failure

4.1.0 Environmental Conditions: Failures in electrically controlled equipment can result from

exposure to harmful environmental conditions… equipment terminals, cable

terminations, and relay contacts.

Dirt and other contaminants such as fumes, vapors, abrasives, soot, grease, and oils can

cause electronic devices to operate abnormally until they finally break down.

Equipment that is subjected to unusual amounts of dust and other airborne particles tends

to fail due to overheating caused by clogged … required to dissipate heat generated in the

unit.

Heat increases the resistance of circuits, thereby increasing the current. Heat causes

materials to expand, dry out, crack, and/or blister.

4.4.0 Electrostatic Discharge: Electrostatic discharges that occur at or near electronic

equipment can damage sensitive semi-conductor circuits and devices.

When subjected to ESD, a sensitive electronic component can experience a catastrophic

failure, meaning it is immediately damaged to the point at which it is totally inoperative

… in a poor system performance and eventual system failure.

4.4.1 Grounding: Always ground yourself before touching the PC board or components.

4.5.0 Thermistor Failure: the resistance of a thermistor itself can be tested with an ohmmeter.

5.0.0 Electronic Controls in Heating Systems: Following are the highlights of the operating

sequence for this unit. (4 bullets).


Section Highlight

6.1.0 Cooling Systems

6.2.0 Heat Pumps

Figure 12 Input and output signals

03401-09 Construction Drawings and Specifications

2.0.0 Reading Drawings: Use this procedure to familiarize yourself with an available set of

drawings: Step 1 -14.

2.1.0 Site Plan: The site plan indicates the location of the building on the land site. It may

include topographic features such as contour lines, trees, and shrubs. It may also include

some construction features such as walks, driveways, curbs, and gutters.

Figure 2 Site Plan

On large commercial jobs, a utility site plan may also be included … power or

communication system cables, and other facilities.

2.2.0 Plan Views (Floor, Roof, and Ceiling Plans): It shows the length and width of the

building and the location of the rooms and other spaces that the building contains.

Figure 3 Floor plans for a building

2.3.0 Elevation Drawings: The elevation view of a structure (Figure 6) shows the exterior

features of that structure.

Figure 6 Elevation drawing

2.4.0 Schedules: They are tables shown on various drawings throughout the drawing set that

identify the types and sizes of items used by the different trades in the construction of a

building.

Schedules shown on the related plumbing plans and electrical plans may …. Shows

schedules typical of those found on mechanical plans.

Figure 7 Mechanical equipment schedules

2.6.0 Section Drawings: Section drawings are cutaway views that allow the viewer to see the

inside of a structure or how something is put together internally.

Figure 9 Section drawing showing building construction

2.7.0 Plumbing Plans: Plumbing plans show the layout of fixtures, water supply lines, natural

gas piping, and lines to sewage disposal systems.


Section Highlight

2.8.0 Mechanical Plans: mechanical plans show the heating, ventilation, and air conditioning

systems, as well as other mechanical systems for a building.

Figure 11 Sanitary plumbing plan

Figure 12 Plumbing legend

Details of the mechanical plan are usually overlaid on tracings of the various building

floor plans from which … Figure 13 shows an example of a typical HVAC mechanical

plan.

As appropriate, detailed views describing the installation of the HVAC equipment are

shown … and the pipe sizes for major items of HVAC equipment.

Figure 13 HVAC mechanical plan

Figure 14 Refrigeration piping schematic

Mechanical plans also normally include an HVAC legend listing the various symbols …

(Figure 16) and information about relevant HVAC system specifications (Figure 17).

2.9.0 Electrical Plans: For smaller construction jobs, the electrical plans are usually shown on

the architectural floor plans … information about the electrical system installation.

3.0.0 Request for Information: The general contractor then relays the RFI to the architect or

engineer.

Figure 16 Schedule of HVAC systems

4.0.0 Specifications

4.4.0 Format

4.4.1 CSI Format: The most commonly used specification-writing format used in North

America is the Master Format. This standard was developed jointly by the Construction

Specifications Institute) (CSI).

Figure 20 2004 Master Format. Note: Division 23: Heating, Venting, and Air

Conditioning

5.0.0 Shop Drawings: A second type of shop drawing (or submittal pertains to the purchase of

special items … out so that the architect or engineer responsible can correct the problem.

5.1.0 Cut Lists: After the shop drawings are complete, or as they are drawn (depending on the

workload) … matches the numbers on the shop drawings.


Section Highlight

5.1.0 Cut Lists: After the shop drawings are complete or as they are drawn (depending on the

workload) … matches the numbers on the shop drawing.

6.0.0 Submittals: Submittals are documents that illustrate special pieces of equipment or

accessories that are to be furnished and installed by the subcontractor.

7.0.0 As-Built Drawings: As-built drawings must be made on alteration or addition jobs, on

jobs where modifications must be made to make way for other mechanical trades, or to

alter the location of a component.

8.0.0 Takeoffs: The takeoff procedure involves surveying, measuring, and counting all

materials and equipment … should be taken off in the following order: 1-10.

8.1.0 Takeoff Tools and Materials: The following materials will make the measuring,

counting, and calculating tasks easier. (8 bullets) #3: An electronic wheel scaler or

similar device for measuring duct and piping runs (should have scales of 1/8”, ¼”, and

½”.

8.2.0 Selecting Equipment and Materials

8.2.1 Ductwork: The materials commonly used in duct run system construction are the

following: (9 bullets). Duct construction is classified in terms of operating pressure and

air velocity. The common classifications are shown in Table 1.

Table 1 Pressure and velocity

8.2.2 Duct hangers: Ductwork must not be hung from overhead piping or ceiling hanger irons

… Trapeze-type hangers are recommended for large ducts.

Duct sizes are determined according to airflow rates (cfm), velocity (fpm), and duct

friction losses.

03406-09 System Startup and Shutdown:

2.0.0 Steam/Hot water Boilers and Systems

2.1.0 Shutdown: Unless proper procedures are followed before taking boilers off line, severe

corrosion … to produce extensive pitting of metal surfaces.

2.1.1 Boiler Shutdown Concerns: Corrosion that could occur during the layup period can be

greatly reduced by thoroughly … from the boiler’s fire-side components immediately

after shutdown of the boiler.

2.1.2 Boiler Preparation for Dry Storage: Dry storage of a boiler is typically done when the

boiler is subjected … or when it will be out of service for more than a month.


Section Highlight

2.1.3 Boiler Preparation for Wet Storage: The following procedure outlines the preparation

of the typical oil-fired steam boiler for wet storage. Step 1 -8.

Step 2: valve the boiler off from the rest of the system, and then refill it to overflowing

with treated water.

Step 3: Add the water treatment chemicals needed to condition the added amount of

water that is now above the boiler’s normal water line.

2.2.0 Steam Boiler System Start-up: The start-up procedure typical of that used with an oil-

fired steam boiler is outlined here. Step 1 -16.

Step 4: Make sure that the main steam stop valve is closed.

Step 7: The boiler burner and control system should allow the boiler water to warm …

position and the MANUAL FLAME control to the LOW-FIRE position.

Step 9: When the steam gauge shows pressure in the boiler, blow down the gauge glass,

water column, and low-water cutoff as applicable.

2.3.0 Hot-water Boiler Startup

2.3.1 Filling and venting a Hot-water System: Because a hot-water boiler is completely filled

with water, the hot-water outlet usually … the expansion tank where the air is properly

released.

2.3.2 Hot-water System Operating Temperatures: The minimum boiler water temperature

recommended for hot-water boilers is 140 F.

Figure 4 Typical hot-water boiler circulation chart

3.0.0 Reciprocating Chillers and Water Systems

3.1.0 Startup: Step 1 -17.

Step 6: Check the pH of the chilled water to determine its acidity or alkalinity … A pH of

7 is considered neutral.

4.0.0 Centrifugal Chillers and Water Systems

4.1.0 Startup

Figure 9 Typical centrifugal/screw chiller sequence of operation


Section Highlight

The chilled water temperature is compared to the chiller’s leaving (or enetering) water

temperature control point and deadband … For example, a 1 F deadband controls the

water temperature to within + 0.5 F.

4.2.0 Normal Shutdown: When a stop command occurs, the automatic sequence for the

shutdown … events F and G in Figure 9 and described below:

- Event F

- Event G

4.3.0 Extended Shutdown

5.0.0 Screw Chillers and Water Systems

6.0.0 Cooling Tower and Water Systems

6.1.0 Startup: Step 1 -10.

Step 9: Adjust the bleed-off rate to match the rate set by the system water treatment

program … small amount of the water circulating in a system.

6.2.0 Periodic Maintenance After Startup: Cooling towers are highly susceptible to the

growth of algae, bacteria, and other living organisms … if manufacturer information is

not available, table 5 can be used as a guide.

6.3.0 Winter Operation: When a cooling tower is used in subfreezing temperatures … need to

winterized.

Table 5 Cooling Tower/Open Recirculating Water System Maintenance

6.4.0 Shutdown

7.0.0 Air handling Unit/Air Distribution System

7.1.0 Startup

7.1.1 Preliminary Checks: Step 1-8.

Step 4: Inspect the complete supply air system from the supply air fan … verify that: a-c.

7.1.2 Startup and Air Distribution System Balance: Step 1 – 10.

Step 7: Use the values of supply fan rpm and total static pressure measured in Steps 5 and

6 … static pressure is 1.40 in. w.g. and the fan is running at 900 rpm.

Figure 14 Example of a typical fan curve chart


Section Highlight

Step 10: b. Use a velocity pressure/velocities chart (Figure 16) to convert each of the …

velocity in feet per minute (fpm).

Figure 16: Velocity pressure/velocities chart

7.2.0 Shutdown: Clean duct using portable and/or truck-mounted … to dislodge dirt and

debris in the ductwork.

8.0.0 Packaged Year-Round Air Conditioning Units

8.1.0 Start-up

8.2.0 Shutdown

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