A.O. Smith GCV-30 LP, GCV-30, GCV-40, GCV-50 LP, GCV-50 Technical Documents

...

Service Handbook

Residential FVIR Gas Water Heaters

MODELS:

GCV, GCVH, GVR, GCVL, GVRL, GCVT - SERIES 300/301

XCV, XVR, XCVL, XGV, XVRL, XCVT - SERIES 300/301

LOW LEAD

CONTENT

THIS SERVICE HANDBOOK IS FOR USE BY QUALIFIED SERVICE PROFESSIONALS ONLY.

327726-001

May 2014

TABLE OF CONTENTS

General Safety .................................................................................................................................................... 4

Completed Installation (typical) ......................................................................................................................... 6

System Basics ..................................................................................................................................................... 7

Honeywell® Gas Control Valve/Thermostat ............................................................................................................................ 7

Gas Pressures ............................................................................................................................................................ 7

BASICS

Combustion Chamber with TCO Switch .................................................................................................................................. 8

Lighting the Pilot / Diagnostic Flash Codes ......................................................................................................... 9

Lighting the Pilot: ................................................................................................................................................................... 9

If the Status Light Does Not Blink: ........................................................................................................................................... 9

If the Pilot Does Not Light: ...................................................................................................................................................... 9

If the Pilot Lights but the Status Light Does Not Blink: ............................................................................................................ 9

Diagnostic Flash Codes .......................................................................................................................................................... 10

Temperature Settings ................................................................................................................................................ 7

0 Flashes (LED not lit) ............................................................................................................................................ 10

Status Light On (solid) ........................................................................................................................................... 10

1 Flash ..................................................................................................................... .............................................. 10

2 Flashes ................................................................................................................................................................ 10

4 Flashes ................................................................................................................................................................ 10

5 Flashes ................................................................................................................................................................ 10

7 Flashes ................................................................................................................................................................ 10

8 Flashes ................................................................................................................................................................ 10

System Checks .................................................................................................................................................. 11

Draft Test .............................................................................................................................................................................. 11

Connections Check ................................................................................................................................................................ 11

Gas Pressure Checks .............................................................................................................................................................. 11

Thermopile Check (Open Circuit) .......................................................................................................................................... 12

Thermopile Check (Closed Circuit) ........................................................................................................................................ 12

Common Issues ................................................................................................................................................ 13

No Hot Water ........................................................................................................................................................................ 13

Not Enough Hot Water .......................................................................................................................................................... 13

Lower Seasonal Water Temperatures ....................................................................................................... 13

Faulty Shower Control Valve/Faucet Valve ............................................................................................... 14

Thermostat Set Too Low ........................................................................................................................... 14

An Increase in Hot Water Usage ............................................................................................................... 14

Undersized Water Heater ......................................................................................................................... 14

Reversed Water Connections ................................................................................................................... 14

Leak in the Plumbing System ................................................................................................................. 14

Sediment Buildup in the Tank ................................................................................................................... 14

2 • Residential Standard Gas Water Heater Service Handbook

Tank Leak ............................................................................................................................................................................... 15

Condensation .......................................................................................................................................................... 15

Leaking Plumbing Connections ............................................................................................................................... 15

Drips from the T&P Relief Valve Discharge Pipe ..................................................................................................... 15

Temperature Too High ........................................................................................................................................................... 16

Low Water Pressure .............................................................................................................................................................. 16

Water Odor ........................................................................................................................................................................... 16

Service Procedures ........................................................................................................................................... 17

Removing the Manifold/Burner Assembly ............................................................................................................................ 17

Removing the Burner from the Manifold/Burner Assembly ................................................................................................. 17

Replacing the Pilot/Thermopile Assembly ............................................................................................................................ 17

External Inspection and Cleaning of the Base-Ring Filter ..................................................................................................... 18

Cleaning the Combustion Chamber and Flame Arrestor....................................................................................................... 18

Replacing the Manifold/Burner Assembly ............................................................................................................................ 19

Testing the Igniter System ..................................................................................................................................................... 19

Removing and Replacing the Gas Control Valve/Thermostat ................................................................................................ 20

Removing the Gas Control Valve/Thermostat: ........................................................................................................ 20

Replacing the Gas Control Valve/Thermostat: ........................................................................................................ 20

Draining and Flushing ............................................................................................................................................................ 20

BASICS

Supplements..................................................................................................................................................... 21

Evaluating Combustion and Ventilation Air Supply ............................................................................................................... 21

Attic Installations .................................................................................................................................................................. 23

Overview ................................................................................................................................................................. 23

Pilot Outage .................................................................................................................. .......................................... 23

Elevated Air Temperature: ........................................................................................................................ 24

Insufficient Makeup Air ............................................................................................................................ 24

Blocked Air Screen or Flame Arrestor ....................................................................................................... 24

Improper Venting of the Water Heater .................................................................................................... 24

Decompression ........................................................................................................................................ 25

Wind ........................................................................................................................................................ 25

Water Damage .................................................................................................................. ...................................... 25

Elevated Water Temperature .................................................................................................................................. 25

Field Installation of Draft Hoods ........................................................................................................................................... 26

Tools and Materials ................................................................................................................................................. 26

Types of Draft Hoods Covered in this Section ......................................................................................................... 26

Types of Vent Pipe Covered in this Section ............................................................................................................. 27

Installation Procedure ........................................................................................................ ..................................... 27

Coupling .................................................................................................................................................................. 27

Type B Draft Hood Connectors ................................................................................................................................ 28

Residential Standard Gas Water Heater Service Handbook • 3

GENERAL SAFETY

Your safety and the safety of others is extremely important in the servicing of this water heater. Many safety-related messages and instructions have been provided in this handbook and on your water heater to warn you and others of a potential hazard. Read and obey all safety messages and instructions throughout this handbook as well as those found in the Installation Instructions/ Use & Care Guide.

It is very important that the meaning of each safety message is understood by you and others who service this water heater. The information contained in this handbook is designed to answer commonly faced situations encountered in the operation of the standard Residential Gas product line and is not meant to be all-inclusive. If you are experiencing a problem not covered in

BASICS

this handbook, please contact the Technical Information Center listed on the back cover of this handbook for further assistance. Additional information is also available on the web site listed on the back cover of this handbook.

This handbook is intended for use by licensed plumbing professionals and reference should be made to the Installation Instructions and Use & Care Guide accompanying the product. This handbook contains supplemental information to the Installation Instructions and Use & Care Guide.

When servicing residential water heaters, it is essential that you return the unit to a safe condition before you leave the site. All original components must be re-installed and all safety measures must be implemented. In addition, the recommended water temperature setting is 120° F.

IMPORTANT: It is recommended that on every service call, an inspection & cleaning of the base ring filter and flame arrestor be performed. See page 18.

Tools Required (for servicing gas models):

• Phillips head screw driver

• 3/8, 7/16, & 3/4 inch open end wrenches

• 3/16 inch Allen wrench

• 1-1/16 inch – 6 point – socket – for anode removal

• Electrical multimeter (with alligator leads)

• Digital or analog manometer

• Gas pressure gauge

• Water pressure gauge

• Thermometer

• Hose – to drain tank

• Container – to measure gallons per minute flow

Digital Manometer

4 • Residential Standard Gas Water Heater Service Handbook

Fire or Explosion Harzard

Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other appliance.

Avoid all ignition sources if you smell Natural or LP gas. Do not expose water heater control to excessive gas pressure.

Use only gas shown on rating plate. Maintain required clearances to combustibles. Keep ignition sources away from faucets after extended

period of non-use.

BASICS

Read instruction manual before

installing, using or servicing

water heater.

Fire or Explosion Harzard

Hydrogen gas can be produced in a hot water system after a period of non-use (generally two or more weeks).

Hydrogen gas is extremely flammable and can ignite.

To return hot water system to service, open a hot water faucet in kitchen for several minutes before using electrical appliances.

Do not smoke or have open flame near faucet while it is open. Leave hot water faucet open until the sound of escaping air stops.

After extended period of non-use,

purge gases from hot water system.

Residential Standard Gas Water Heater Service Handbook • 5

COMPLETED INSTALLATION ΈTYPICALΉ

Exhaust Vent to

Ouside of Building

Union

Gas Supply

BASICS

See Labels and Installation Instructions and Use & Care Guide for clearances.

Union

To Fixtures - Hot

Tempered Water

Untempered Hot Water

To Fixtures

Cold

Water

Inlet

Water

Shut-Off

Valve

Temperature-Pressure Relief Valve

with discharge piped to an

adequate drain. Do not cap or plug.

Supply- Cold*

*Massachusett: Install a vacuum relief in cold water line per section 19 MGL 142.

Expansion Tank

Pressurized to Equal

Supply Water Pressure*

(Relieve water pressure

on the expansion tank

before adjusting air

pressure.)

Hot Water Outlet

Mixing Valve

(Set to 120°F)

Follow the Mixing

Valve Manufacturer’s

Instructions

Union

Sediment Trap

3” Minimum.

Base Ring Filter:

Air is drawn in for combustion. Keep area clean

and free from flammables and flammable vapors.

Manual Gas

Shut-off Valve

Gas Control Valve/Thermostat

Recommended setting of 120°F.

Do not cap or plug.

6” Maximum Air Gap

NOTE: Local codes

may vary.

Drain

Metal Drain Pan piped to an adequate drain. NOTE: Drain pan diameter must be at least 2 inches wider than the diameter of the water heater.

The water heater must be installed according to all local and state codes or in the absence of local and state codes, the “National Fuel Gas Code” ANSI Z223.1(NFPA 54)- current edition.

* NOTE: If on a well system, the expansion tank should be set to the maximum pressure of the pump tank.

Figure 1.

6 • Residential Standard Gas Water Heater Service Handbook

SYSTEM BASICS

Honeywell® Gas Control Valve/Thermostat

Water heaters covered by this handbook are equipped with Honeywell gas control valve/thermostats.

• The Honeywell valve uses a thermopile instead of a thermocouple as did previous designs.

• Heat on the thermopile generates 750 to 900 millivolts (open circuit).

• When heated by the pilot and connected to the Honeywell control, the thermopile generates at least 350 millivolts (closed circuit). This voltage opens the power head in the control, allowing gas to flow. It also powers the onboard diagnostics (status light). See Figure 2.

• The Honeywell valve uses a standard push-button piezo igniter. See “Spark Igniter” in Figure 2B.

• Status codes are printed on the face of the control for easy reference (Figure 2B.)

• The LED status light shows the current status of the control as well as possible error codes for easy diagnosis. For more information on

error codes, see “Lighting the Pilot / Diagnostic Flash Codes” on page 9.

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Pilot

Thermopile

Figure 2.

Gas Pressures

Ensure that the following pressures are observed and maintained:

Table 1. GAS PRESSURES

GAS MAXIMUM

SUPPLY

PRESSURE

NAT 14 InWC 5.0 InWC

LP 14 InWC 10.0 InWC

Min. Supply Pressure: See Rating Plate.

MANIFOLD

GAS

PRESSURE

(± 0.4 InWC)

(± 0.5 InWC)

The gas control valve\thermostat also includes a temperature limiting ECO (Energy Cut Off) system. This system will shut off the water heater if the water temperature becomes excessive. Should the water temperature get too high, the main burner and pilot will shut off automatically. Once the pilot is relit, the status light will flash a code (4 flashes), indicating an overtemperature condition. See “Lighting the Pilot / Diagnostic Flash Codes” on page 9 for more information.

NOTE: Honeywell is a registered trademark of Honeywell International, Inc.

Temperature Seƫ ngs

The water temperature setting can be adjusted from 55°F to 155°F. Simply turn the gas control/temperature Knob to the desired setting/temperature. See Figure 3.

NOTE: The temperatures indicated are approximates. The actual temperature of the heated water may vary.

BASICS

Figure 2B

Temperature Control Knob

Temperature control ranges:

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* Some models do not

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Residential Standard Gas Water Heater Service Handbook • 7

Scalding Risk

A water heater can make water hot enough to

cause severe burns instantly, resulting in severe injury or death. Higher temperatures increase

BASICS

the risk of scalding, but even at 120°F, hot water can scald. See Table 2. Thermostatic mixing valves at each point of use reduce the risk of scalding.

HONEYWELL® GAS CONTROL VALVE/THERMOSTAT

GAS CONTROL/TEMPERATURE KNOB

VAC

IGNITER

TEMPERATURES SHOWN ARE APPROXIMATES AND MAY VARY. SOME MODELS ARE CERTIFIED FOR 180°F. SEE RATING PLATE.

Figure 3.

Table 2.

Water Temperature

120°F (49°C) More than 5 minutes

125°F (52°C) 1½ to 2 minutes

130°F (54°C) About 30 seconds

135°F (57°C) About 10 seconds

140°F (60°C) Less than 5 seconds

145°F (63°C) Less than 3 seconds

150°F (66°C) About 1½ seconds

155°F (68°C) About 1 second

IMPORTANT: Water temperature in the tank can be higher than the thermostat setting. Some of the reasons are:

• Incoming water temperature is

higher than the set point (e.g., solar-heated water).

§140°F

§130°F

120°F MARK

STATUS LIGHT

§55°F

Time to Produce a Serious Burn

§150°F

§155°F

• The water heater and/or pipes are located in an area with high ambient temperatures (e.g., an attic). See also “Attic Installations” on page 23.

• Certain usage patterns, such as short hot water draws or no hot water use for long periods of time, can cause the tank water temperature to rise higher than the thermostat setting. Modern water heaters are very well insulated and retain heat so efficiently that, under certain circumstances, the tank water temperature can increase over time, particularly when hot water is not being used. This “heating” effect can be caused by the pilot flame itself.

CombusƟ on Chamber with TCO Switch

Combustion air is drawn through the base-ring filter and flame arrestor and into the combustion chamber. (See Figure 5.) Sufficient combustion air is critical to the operation of the water heater.

IMPORTANT: The flame arrestor and filter should be inspected and cleaned during each service call. See page 18 for instructions.

Also, each water heater covered by this handbook is equipped with a resettable TCO switch (thermal switch), designed to shut off the gas supply in the event that the water heater has been exposed to high combustion chamber temperatures caused by one of the following events:

• Flammable vapors (e.g., spilled

gasoline)

• Poor combustion caused by a

blocked vent

• Insufficient combustion air.

A resettable thermal switch is illustra

ted in Figure 4. Its reset button

is located in the center of the switch, directly between the terminals.

IMPORTANT: If the thermal switch has been tripped, determine the cause and correct it before returning the

water heater to service. Ensure that

there are no flammable vapors present. However, a tripped thermal

switch is most likely caused by poor combustion (e.g., blocked vent or dirty filter/arrestor).

THERMAL SWITCH (TCO) LOCATION

THERMAL

SWITCH

(TCO)

Figure 4.

FLAME ARRESTOR

BASE-RING FILTER

COMBUSTION CHAMBER

Figure 5.

8 • Residential Standard Gas Water Heater Service Handbook

LIGHTING THE PILOT / DIAGNOSTIC FLASH CODES

LighƟ ng the Pilot:

1. Read and follow the lighting instructions on the water heater’s label.

2. Turn the control knob to “Pilot.” Press the knob in fully and hold it in. (The knob will travel in about 1/4inch if it is set to Pilot correctly.)

3. While holding the control knob in, click the igniter button continuously for up to 90 seconds or until the Status Light begins to blink.

If the status light does not begin to blink after 90 seconds, STOP. Release the control knob. Wait 10 minutes before attempting to relight the Pilot. Repeat these steps 2-3 times, if necessary.

The circuitry in this gas valve requires that you wait 10 minutes between lighting attempts.

If the Status Light blinks, release the gas control/temperature knob and turn it to the desired setting. (“Hot” is approximately 120°F).

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Figure 6.

If the Status Light Does Not Blink:

1. Wait 10 minutes before another lighting attempt.

2. If the status light did not blink, repeat the lighting procedure by following the lighting instructions on the water heater’s label. Remove the outer

door. The control knob must be set to Pilot and held in continuously while clicking the igniter button (about once per second for up to 90 seconds). To observe the Pilot, remove the outer door and look through the view port (sight glass). See Figure 7.

3. Continue clicking the Igniter button (for up to 90 seconds) until pilot lights.

4. Once the pilot is lit, continue to hold the control knob in until the Status Light begins to blink.

5. Release control Knob and set Knob to desired temperature setting. (“Hot” is approximately 120°F.)

6. Replace the outer door.

If the Pilot Does Not Light:

1. Wait 10 minutes before another lighting attempt. If the pilot does not light, the Igniter may not be sparking or the unit may not be getting gas (or for a new installation, there may still be air in the gas line). Each time you click the igniter button, you should be able to see the spark by looking through the view port. See Figure 7. (You may have to darken the room lights to see the spark.) You do not have to push the Control Knob in to check the Igniter button. Simply look through the sight glass while clicking the Igniter button and look for a spark. If you can’t see a spark when the Igniter button is clicked, check the wiring connections from the Igniter button and make sure that they are tight.

2. If you see the igniter spark, try relighting the pilot by following the instructions on the water heater’s label. Ensure that the gas supply is turned on. There may be air in the gas line, and several lighting attempts

may be needed to completely fill the line with gas and successfully light the pilot.

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Figure 7.

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THERMAL

SWITCH

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If the Pilot Lights but the Status Light Does Not Blink:

1. If the pilot lights, continue to hold the control knob in until the status light blinks. If the pilot is lit and remains lit for 90 seconds and the Status Light still does not blink, the thermopile connections may be loose, the thermal switch may need to be reset, or the thermopile may be defective.

2. Remove the outer door.

3. Press the reset button on the thermal switch (TCO switch). See Figure 7.

4. If the switch clicks, it may have tripped. Do not light the pilot if flammable vapors are present. Check flame arrestor for signs of discoloration (which could be caused by flammable vapors). If the flame arrestor is discolored, do not attempt to relight the Pilot. Have the water heater inspected by a qualified service technician.

5. Check the wiring connections from the thermopile and thermal switch (TCO) to the gas control valve/thermostat. Ensure that all wiring connections are tight. See Figure 7.

6. Replace the outer door.

PILOT/FLASH CODES

Residential Standard Gas Water Heater Service Handbook • 9

7. Wait 10 minutes and try to light the Pilot according to the instructions on the water heater’s label.

8. While clicking the igniter button continuously, the control knob must be set to Pilot and held in until the Status Light blinks. Once the status light blinks, release the control knob and set the knob to the desired temperature setting. (“Hot” is approximately 120°F.)

DiagnosƟ c Flash Codes

NOTE: In each case, the flash code will

occur, followed by a 3 second pause, and then will repeat.

PILOT/FLASH CODES

0 Flashes (LED not lit)

Indication/Condition:

Control Off/Pilot Out.

Check/Repair:

1. Follow the lighting instructions on the

front of the water heater and attempt to relight the pilot. Confirm that the pilot is lit by looking through the viewport (Figure 16, p. 17).

2. If pilot will light but does not

hold, check for a tripped thermal switch. (Measure continuity by placing a meter lead on each of the two terminals. Continuity means that it was not tripped.) If thermal switch is tripped, check for flammable vapors in the area and ensure that the unit has adequate combustion air and proper draft before relighting. (You can reset the thermal switch by pressing the reset button in its center.) Also, ensure that the filter and flame arrestor are clean (p. 18).

3. If the pilot will light and does hold,

record any status codes and follow the procedures relating to that code.

4. If pilot will not light at all, verify the

piezo igniter is producing a spark and the unit is getting the correct supply gas pressure. See “Testing

the Igniter System” (p. 19); “Gas Pressure Checks” (p. 11). Also, check the thermopile wiring connections (Figure 16, p. 17).

Status Light On (solid)

Indication/Condition:

Pilot light was recently extinguished and the thermopile is cooling down.

Check/Repair:

1. Turn the gas control valve/ thermostat knob to OFF.

2. Wait 10 minutes for the thermopile to cool, then attempt to relight the pilot by following the lighting instructions on the water heater’s label. NOTE: This gas control valve/ thermostat has built-in circuitry that requires waiting 10 minutes between lighting attempts.

Until the Thermopile reaches its normal operating temperature, the status light will not blink, even if the pilot is lit. It may take up to 90 seconds of continuous pilot operation before the thermopile reaches normal operating temperature and the Status Light starts to blink.

1 Flash

Indication/Condition:

Normal Operation (bright/dim heartbeat)

Check/Repair: No corrective action necessary.

2 Flashes

Indication/Condition:

Thermopile voltage low.

Check/Repair:

1. Check all wiring connections for loose or damaged wires. Correct if needed.

2. Check the millivolt output on the thermopile. If output is less than 350 millivolts DC, replace the thermopile.