Air Conditioning and Refrigeration

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Air Conditioning and Refrigeration

Air Conditioning and Refrigeration

Authors: Rex Miller and Mark R. Miller

Published: April 2006

eISBN: 9780071487412 0071487417 | ISBN: 9780071467889

Contents

Preface

Acknowledgments

1 Air-Conditioning and Refrigeration Tools and Instruments

Performance Objectives

Tools and Equipment

Pliers and Clippers

Fuse Puller

Screwdrivers

Wrenches

Soldering Equipment

Drilling Equipment

Knives and Other Insulation-Stripping Tools

Meters and Test Prods

Tool Kits

Gages and Instruments

Pressure Gages

Gage Selection

Line Pressure

Effects of Temperature on Gage Performance

Care of Gages

Gage Recalibration

Thermometers

Pocket Thermometer

Bimetallic Thermometers

Thermocouple Thermometers

Resistance Thermometers

Superheat Thermometer

Superheat Measurement Instruments

Halide Leak Detectors

Setting Up

Lighting

Leak Testing the Setup

Adjusting the Flame

Detecting Leaks

Maintenance

Electrical Instruments

Ammeter

Voltmeter

Ohmmeter

Multimeter

Wattmeter

Other instruments

Air–Filter Efficiency Gages

Air-Measurement Instruments

Humidity-Measurement Instruments

Vibration and Sound Meters

Service Tools

Special Tools

Vacuum Pumps

Vacuum Pump Maintenance

Vacuum Pump Oil Problems

Operating Instructions

Evacuating a System

Charging Cylinder

Charging Oil

Changing Oil

Mobile Charging Stations

Tubing

Soft Copper Tubing

Hard-Drawn Copper Tubing

Cutting Copper Tubing

Flaring Copper Tubing

Constricting Tubing

Swaging Copper Tubing

Forming Refrigerant Tubing

Fitting Copper Tubing by Compression

Soldering

Soft Soldering

Silver Soldering or Brazing

Testing for leaks

Cleaning and Degreasing Solvents

Review Questions

2 Development of Refrigeration

Performance Objectives

Historical Development

Structure of Matter

Elements

Atom

Properties of Matter

Pressure

Pressure Indicating Devices

Pressure of Liquids and Gases

Atmospheric Pressure

Gage Pressure

Absolute Pressure

Compression Ratio

Temperature and Heat

Specific Heat

Heat Content

Sensible Heat

Latent Heat

Other Sources of Heat

Refrigeration Systems

Refrigeration from Vaporization (Open System)

Basic Refrigeration Cycle

Capacity

Refrigerants

Refrigerant Replacements and the Atmosphere

Review Questions

3 Voltage, Current, and Resistance

Performance Objectives

Ohm's Law

Series Circuits

Parallel Circuits

Current in a Parallel Circuit

Resistance in a Parallel Circuit

AC and DC Power

Phase

Power in DC Circuits

Power Rating of Equipment

Capacitors

How a Capacitor Works

Capacity of a Capacitor

Dielectric Failure

Basic Units of Capacitance

Working with Capacitive Values

Capacitor Types

Capacitor Tolerances

The AC Circuit and the Capacitor

Uses of Capacitors

Inductance

Four Methods of Changing Inductance

Self-Inductance

Mutual Inductance

Inductive Reactance

Uses of Inductive Reactances

Transformers

Transformer Construction

Turns Ratio

Transformer Applications

Semiconductors

Diodes

Transistors

Silicon-controlled Rectifier (SCR)

Bridge circuits

Wheatstone Bridges

Variable Resistor

Sensors

Temperature Elements

Humidity Elements

Controllers

Single-Element Controllers

Dual-Element Controllers

Actuators

Electro-Hydraulic Actuators

Thermal Actuators

Auxiliary Devices

Electronic Compressor Motor Protection

Operation

Troubleshooting the Control

Restoring Service

Review Questions

4 Solenoids and Valves

Performance Objectives

Industrial Solenoids

Tubular Solenoids

Frame Solenoids

Applications

Solenoids as Electromagnets

Solenoid Coils

Servicing Coils

Solenoid Valves in Circuits

Refrigeration Valve

Review Questions

5 Electric Motors: Selection, Operational Characteristics, and Problems

Performance Objectives

Construction of an Induction Motor

Single-Phase Motors

Shaded-Pole Motor

Split-Phase Motor

Capacitor-Start Motor

Sizes of Motors

Cooling and Mounting Motors

Direction of Rotation

Synchronous Motor

Theory of Operation

Synchronous Motor Advantages

Properties of the Synchronous Motor

Electric Motors

Starting the Motor

Repulsion-Induction Motor

Capacitor-Start Motor

Permanent Split-Capacitor Motor

Shaded-Pole Motor

Split-Phase Motor

Polyphase-Motor Starters

Reduced-Voltage Starting Methods

Primary-Resistor Starting

Autotransformer Starting

Part-winding Starting

Wye-delta or Star-delta Starters

Multispeed Starters

Consequent-Pole Motor Controller

Full-Voltage Controllers

Starting Sequence

Protection Against Low Voltage

Time-Delay Protection

Electric Motors: Their Uses, Operation, and Characteristics

Motor Rotation

Variable-Speed Drives

Troubleshooting Electric Motors with a Volt-Ammeter

Split-Core AC Volt-Ammeter

Testing for Grounds

Testing for Opens

Checking for Shorts

Testing Squirrel-Cage Rotors

Testing the Centrifugal Switch in a Split-Phase Motor

Test for Short Circuit Between Run and StartWindings

Test for Capacitors

Using the Megohmmeter for Troubleshooting

Insulation-Resistance Testing

Measuring Insulation Resistance

Power Tools and Small Appliances

Hermetic Compressor Systems

Circuit Breakers and Switches

Coils and Relays

AC Motor Control

Motor Controller

AC Squirrel-Cage Motor

Enclosures

Code

Protection of the Motor

Contactors, Starters, and Relays

Motor-Overload Protector

Motor-Winding Relays

Solenoid Valves

Refrigeration Valve

Application

Operation

Installation

Temperature Controls

Bimetallic Thermostats

Thermostat Construction and Wiring

Defrost Controls

Defrost Timer Operation

Hot-Gas Defrosting

Motor Burnout Cleanup

Procedure for Small Tonnage Systems

Procedure for Large Tonnage Systems

Reading a Schematic

Review Questions

6 Refrigerants: New and Old

Performance Objectives

Classification of Refrigerants

Common Refrigerants

Freon Refrigerants

Molecular Weights

Flammability

Toxicity

Skin Effects

Oral Toxicity

Central Nervous System (CNS) Effects

Cardiac Sensitization

Thermal Decomposition

Applications of Freon Refrigerants

Reaction of Freon to Various Materials Found in Refrigeration Systems

Metals

Plastics

Refrigerant Properties

Pressure

Temperature

Volume

Density

Enthalpy

Flammability

Capability of Mixing with Oil

Moisture and Refrigerants

Odor

Toxicity

Tendency to Leak

Detecting Leaks

Sulfur Dioxide

Carbon Dioxide

Ammonia

Methyl Chloride

Ban on Production and Imports of Ozone-Depleting Refrigerants

Phase-out Schedule for HCFCs, Including R-22

Availability of R-22

Cost of R-22

Alternatives to R-22

Servicing Existing Units

Installing New Units

Servicing Your System

Purchasing New Systems

Air Conditioning and Working with Halon

General Information

Leak Repair

Trigger Rates

When Additional Time Is Necessary

Relief from Retrofit/Retirement

System Mothballing

EPA-Certified Refrigerant Reclaimers

Newer Refrigerants

Freon Refrigerants

Classifications

Properties of Freons

Physical Properties

Refrigerant Characteristics

Critical Temperature

Latent Heat of Evaporation

Specific Heat

Power Consumption

Volume of Liquid Circulated

Handling Refrigerants

Storing and Handling Refrigerant Cylinders

Lubricants

R-134a Refrigerant

R-134a Applications

R-12 Systems—General Considerations

R-12 Medium/High Temperature Refrigeration (>0°F evap)

R-12 Low Temperature Refrigeration (<20°F evap)

R-401B

R-402A

R-402B

Reclaiming Refrigerant

Description

Compressor

Oil Separator

Condenser

Filter Drier

Accumulator/Oil Trap

Operation of the Unit

Recovery Plus/Recovery Operations

Storage Cylinder Cooling

Recycle Operation

Recharge Operation

Service Operation

Test Operation

Control Circuits

Troubleshooting

Troubleshooting Approach

Review Questions

7 Refrigeration Compressors

Performance Objectives

Condensers

Air-Cooled Condensers

Water-Cooled Condensers

Hermetic Compressors

Compressor Types

Newer Models Designations and Coding

Hermetic Compressor Motor Types

Resistance Start-Induction Run

Capacitor Start-induction Run

Capacitor Start and Run

Permanent Split Capacitor

Compressor Motor Relays

Current-type Relay

Potential-type Relay

Compressor Terminals

Built-up Terminals

Glass Quick-Connect Terminals

Motor Mounts

Crankcase Heaters

Electrical Systems for Compressor Motors

Normal-Starting Torque Motors (RSIR) with a Current-Type Relay

High-Starting Torque Motors (CSIR) with a Current-Type Relay

High-Starting Torque Motors (CSIR) with a Two-Terminal External Overload and a Remote-Mounted Potential Relay

High-Starting Torque Motors (CSR) with Three-Terminal Overloads and Remote-Mounted Relays

PSC Motor with a Two-Terminal External Overload and Run Capacitor

PSC Motor with an Internal Overload (Line Breaker)

CSR or PSC Motor with the Start Components and an Internal Overload or Line Breaker

Compressors with Internal Thermostat, Run Capacitor, and Supplementary Overload

CSR or PSC Motor with Start Components, Internal Thermostat, and Supplementary External Overload

Compressor Connections and Tubes

Process Tubes

Other Manufacturers of Compressors

Rotary Compressors

Stationary Blade Rotary Compressors

Rotating Blade Rotary Compressors

Screw Compressors

Single Screw

Twin Screw

Making the Rotors

Scroll Compressors

Scroll-Compression Process

Operation

Scroll Compressor Models

Review Questions

8 Condensers, Chillers, and Cooling Towers

Performance Objectives

Condensers

Air-Cooled Condensers

Water-Cooled Condensers

Chillers

Refrigeration Cycle

Motor-Cooling Cycle

Dehydrator Cycle

Lubrication Cycle

Controls

Solid-State Capacity Control

Cooling Towers

Cooling Systems Terms

Design of Cooling Towers

Evaporative Condensers

New Developments

Temperature Conversion

Types of Towers

Crossflow Towers

Fluid Cooler

Review Questions

9 Working with Water-Cooling Problems

Performance Objectives

Pure Water

Fouling, Scaling, and Corrosion

Prevention of Scaling

Scale Identification

Field Testing

Corrosion

Control of Algae, Slime, and Fungi

Bacteria

The Problem of Scale

Evaporative Systems

Scale Formation

How to Clean Cooling Towers and Evaporative Condensers

Determining the Amount of Water in the Sump

Determining the Amount of Water in the Tank

Total Water Volume

Chilled Water Systems

How to Clean Shell (Tube or Coil) Condensers

Safety

Solvents and Detergents

Review Questions

10 Evaporators

Performance Objectives

Coiled Evaporator

Application of Controls for Hot-Gas Defrost of Ammonia Evaporators

Direct-Expansion Systems

Cooling Cycle

Direct Expansion with Top Hot-Gas Feed

Direct Expansion with Bottom Hot-Gas Feed

Flooded Liquid Systems

Flooded-gas Leg Shutoff (Bottom Hot-Gas Feed)

Flooded-Ceiling Evaporator—Liquid-Leg Shutoff (Bottom Hot-Gas Feed)

Flooded-Ceiling Evaporator—Liquid-Leg Shutoff (Top Hot-Gas Feed)

Flooded-Ceiling Blower (Top Hot-Gas Feed)

Flooded-Ceiling Blower (Hot-Gas Feed through Surge Drum)

Flooded Floor-Type Blower (Gas and Liquid-Leg Shutoff)

Flooded Floor-Type Blower (Gas Leg Shutoff)

Liquid-Recirculating Systems

Flooded Recirculator (Bottom Hot-Gas Feed)

Flooded Recirculator (Top-Gas Feed)

Low-Temperature Ceiling Blower

Year–Round Automatic Constant Liquid-Pressure Control System

Dual-Pressure Regulator

Valves and Controls for Hot-Gas Defrost of Ammonia-Type Evaporators

Back-Pressure Regulator Applications of Controls

Refrigerant-Powered Compensating-Type Pilot Valve

Air-Compensating Back-Pressure Regulator

Electric-Compensating Back-Pressure Regulator

Valve Troubleshooting

Noise in Hot-Gas Lines

Review Questions

11 Refrigerant: Flow Control

Performance Objectives

Metering Devices

Hand-Expansion Valve

Automatic-Expansion Valve

Thermostatic-Expansion Valve

Capillary Tubing

Float Valve

Fittings and Hardware

Copper Tubing

Line

Solder

Suction Line P-Traps

Compressor Valves

Line Valves

Driers, Line Strainers, and Filters

Driers

Line Strainers and Filters

Liquid Indicators

Construction

Installation

Bypass Installations

Excess Oil and the Indicator

Alcohol

Leak Detectors

Liquid Water

Hermetic-Motor Burnouts

Hardware and Fittings

Thermostatic-Expansion Valve (TEV)

Valve Location

Bulb Location

External Equalizer

Field Service

Crankcase Pressure-Regulating Valves

Operation of the Valve

Valve Location

Strainer

Brazing Procedures

Test and Operating Pressures

Adjusting the Pressure

Service

Evaporator Pressure-Regulating Valves

Operation

Type of System

Valve Location

Test and Operating Pressures

Service

Head-Pressure Control Valves

Operation

ORO-Valve Operation

ORD Valve Operation

Installation

Brazing Procedures

Test and Operating Pressures

Service

Nonadjustable ORO/ORD System Operation

Discharge Bypass Valves

Operation

Application

Externally Equalized Bypass Valves

Bypass to Evaporator Inlet without Distributor

Installation

Special Considerations

Testing and Operating Pressures

Hot Gas

Malfunctions

Level Control Valves

Capillary Tubes

Float Valve

Level-Master Control

Installation

Electrical Connections

Hand Valves

Oil Return

Oil and Ammonia Systems

Oil and Halocarbon Systems

Conclusions

Other Types of Valves

Service Valves on Sealed Units

Water Valves

Check Valves

Receiver Valves

Accumulators

Purpose

Rating Data

Minimum Evaporator Temperature and Minimum Temperature of Suction Gas at the Accumulator

Installation of the Accumulator

Review Questions

12 Servicing and Safety

Performance Objectives

Safety

Handling Cylinders

Pressurizing

Working with Refrigerants

Lifting

Electrical Safety

Servicing the Refrigerator Section

Sealed Compressor and Motor

Condenser

Filter Drier

Capillary Tube

Heat Exchanger

Freezer-Compartment and Provision-Compartment Assembly

Compressor Replacement

Troubleshooting Compressors

Troubleshooting Refrigerator Components

Compressor Will Not Run

Compressor Runs, but There Is No Refrigeration

Compressor Short Cycles

Compressor Runs Too Much or 100 Percent

Noise

To Replace the Compressor

Compressor Motor Burnout

Cleaning System After Burnout

Replacing the Filter Drier

Replacing the Condenser

Replacing the Heat Exchanger

Repairing the Perimeter Tube (Fiberglass Insulated)

Top-Freezer and Side-by-Side Models

Foam-Insulated 12 and 14 ft[sup(3)], Top-Freezer Models

Foam-Insulated 19 ft[sup(3)] Side-by-Side Models

Replacing the Evaporator-Heat Exchanger Assembly

Top-Freezer, No-Frost Models

Side-by-Side Models

Adding Refrigerant

Low-Side Leak or Slight Undercharge

High-Side Leak or Slight Undercharge

Overcharge of Refrigerant

Testing for Refrigerant Leaks

Service Diagnosis

On the Initial Contact

Before Starting a Test Procedure

Thermostat Cut-Out and Cut-In Temperatures

Freezer- and Provision-Compartment Air Temperatures

Line Voltage

Wattage

Compressor Efficiency

Refrigerant Shortage

Restrictions

Defrost-Timer Termination

Computing Percent Run Time

Start and Run Capacitors

Capacitor Ratings

Start Capacitor and Bleeder Resistors

Run Capacitors

Permanent Split-Capacitor (PSC) Compressor Motors

Field Testing Hermetic Compressors

Warranty Test Procedure

Method of Testing

Resistance Checks

Testing Electrical Components

Installing an Air-Cooled Condensing Unit

General Information

Checking Product Received

Corrosive Environment

Locating Unit

Unit Mounting

Refrigerant Connections

Replacement Units

Evaporator Coil

Interconnecting Tubing

Suction and Liquid Lines

Maximum Length of Interconnecting Tubing

Condensing Unit Installed Below Evaporator

Condensing Unit Installed Above Evaporator

Tubing Installation

Tubing Connections

Leak Testing

Flow-Check Piston

Evacuation Procedure

Checking Refrigerant Charge

Charging by Superheat

Charging by Liquid Pressure

Charging by Weight

Final Leak Testing

Service

Operation

Single-Pole Compressor Contactor (CC)

Compressor Crankcase Heat (CCH)

Hard Start Components (SC and SR)

Time Delay Control (TDC)

Low Ambient Control (LAC)

High- and Low-Pressure Controls (HPC or LPC)

Electrical Wiring

Power Wiring

Control Wiring

Start-up and Performance

Troubleshooting

Review Questions

13 Freezers

Performance Objectives

Types of Freezers

Installing a Freezer

Freezer Components

Wrapped Condenser

Cold-Ban Trim

Shelf Fronts

Vacuum Release

Lock Assembly

Hinges

Lid

Thermostats

Drain System

Wrapper Condenser

Evaporator Coil

Replacing the Compressor

Repairing the Condenser

Installing the Drier Coil

Complete Recharge of Refrigerant

Overcharge of Refrigerant

Restricted Capillary Tube

Testing for Refrigerant Leaks

Troubleshooting Freezers

Portable Freezers

Review Questions

14 Temperature, Psychrometrics, and Air Control

Performance Objectives

Temperature

Degrees Fahrenheit

Degrees Celsius

Absolute Temperature

Converting Temperatures

Psychrometrics

Pressures

Gage Pressure

Atmospheric Pressure

Pressure Measuring Devices

Hygrometer

Properties of Air

People and Moisture

Psychrometric Chart

Air Movement

Convection, Conduction, and Radiation

Comfort Conditions

Velocity

Terminology

Designing a Perimeter System

Locating and Sizing Returns

Airflow Distribution

Selection of Diffusers and Grilles

Air-Volume Requirement

Throw Requirement

Pressure Requirement

Sound Requirement

Casing Radiated Noise

Locating Terminal Boxes

Controlling Casing Noise

Vortex Shedding

Return Grilles

Performance

Return Grille Sound Requirement

Types of Registers and Grilles

Fire and Smoke Dampers

Smoke Dampers for High-Rise Buildings

Ceiling Supply Grilles and Registers

Ceiling Diffusers

Antismudge Rings

Air-Channel Diffusers

Luminaire Diffusers

Room Air Motion

Linear Grilles

Fans and Mechanical Ventilation

Air Volume

Fans and Blowers

Air Volume

Horsepower Requirements

Fan Driving Methods

Selecting a Fan

Applications of Fans

Operation of Fans

Installation of Attic Fans

Routine Fan Operation

Ventilation Methods

Review Questions

15 Comfort Air Conditioning

Performance Objectives

Window Units

Mounting

Electrical Plugs

Maintenance

Low-Voltage Operation

Troubleshooting

Evaporator Maintenance

Automatic Defrosting

Evaporators for Add-on Residential Use

Troubleshooting

Remote Systems

Single-Package Rooftop Units

Smoke Detectors

Firestats

Return-Air Systems

Acoustical Treatment

Volume Dampers

Refrigerant Piping

Troubleshooting

Refrigerant Pipe Sizes

Liquid-Line Sizing

Suction-Line Sizing

Troubleshooting

Mobile Homes

Troubleshooting

Wall-Mounted Ductless Air Conditioners

Fan Control Mode

Restart Function

Rotary Compressor

Review Questions

16 Commercial Air-Conditioning Systems

Performance Objectives

Expansion-Valve Air-Conditioning System

Compressor

Condenser

Expansion-Valve Kit

Troubleshooting

Packaged Cooling Units

Rooftop Heating and Cooling Units

Electrical

Sequence of Operation

Compressor Safety Devices

Maintenance

Troubleshooting

Direct Multizone System

Troubleshooting

Evaporative Cooling System

Absorption-Type Air-Conditioning Systems

Chilled Water Air Conditioning

Refrigerant Cycle

Control System

Chillers

Reciprocating Chillers

Components Used with Chillers

Console-Type Air-Conditioning Systems

Installation

Service

Troubleshooting

Review Questions

17 Various Types of Air Conditioners and Heat Pumps

Performance Objectives

Gas Air Conditioning

Absorption Cooling Cycle

Ammonia Refrigerant in a Gas-Fired System

Gas-Fired Chillers

Chiller-Heater

Changeover Sequence for Chilled Water Operation

Changeover Sequence for Hot Water Operation

Self-Leveling Feature

Absorption Refrigeration Machine

Absorption Operation Cycle

Solar Air Conditioners

History of Solar Cooling

Systems of Solar Cooling

Lithium-Bromide Water Absorption Cycle

Solar Cooling Research Centers

Heat Pumps

Operation

Defrost

Outdoor Thermostat

Special Requirements of Heat Pump Systems

Sizing Equipment

Defrost Cycle

Balance Point

Using the Heat Pump

Review Questions

18 Estimating Load and Insulating Pipes

Performance Objectives

Refrigeration and Air-Conditioning Load

Running Time

Calculating Cooling Load

Wall Gain Load

Air Change Load

Product Load

Miscellaneous Loads

Calculating Heat Leakage

Calculating Product Cooling Load

Capacity of the Machines Used in the System

Air Doors

Insulation

Sheet Insulation

Tubing Insulation

Pipe Insulation

Refrigeration Piping

Pressure-Drop Considerations

Liquid Refrigerant Lines

Interconnection of Suction Lines

Discharge Lines

Water Valves

Multiple-Unit Installation

Piping Insulation

Cork Insulation

Rock-Cork Insulation

Wool-Felt Insulation

Hair-Felt Insulation

Review Questions

19 Installing and Controlling Electrical Power for Air-Conditioning Units

Performance Objectives

Choosing Wire Size

Limiting Voltage Loss

Minimum Wire Size

Wire Selection

Wire Size and Low Voltage

Voltage Drop Calculations

The Effects of Voltage Variations on AC Motors

Selecting Proper Wire Size

Unacceptable Motor Voltages

Calculating Starting Current Values and Inrush Voltage Drops

Single-Phase Current

Three-Phase Circuits

Inrush Voltage Drop

Code Limitations on Amperes per Conductor

Heat Generated within Conductors

Circuit Protection

Standard Rule

Fuses

One-Time Single-Element Fuses

Time-Delay Two-element Fuses

Types of Fuses

Thermostats

Thermostat as a Control Switch

Service

Start Kits

Single-Phase Line Monitors

Time Delays

Head Pressure Control

Pressure Controls

Line-Voltage Head Pressure Controls

Three-Phase Line-Voltage Monitor

Current Sensing

Review Questions

20 Air-Conditioning and Refrigeration Careers

Performance Objectives

Industries that Employ Air-Conditioning and Refrigeration Mechanics

Job Qualifications

The Future

Pay and Benefits

Teaching as a Career

Sources of Additional Information

Review Questions

Appendices

A. Some New Refrigerants

B. Electrical and Electronic Symbols Used in Schematics

C. Programming Thermostats

D. Tools of the Trade (Plus Frequently Asked Questions with Answers)

Glossary

A

B

C

D

E

F

G

H

I

K

L

M

N

O

P

R

S

T

U

V

W

X

Z

Index