State GPX 200 Service Manual
SERVICE HANDBOOK FOR
STANDARD RESIDENTIAL
FVIR GAS WATER HEATERS
MODELS: GPX, GS6, GSX – SERIES 200/201
GS6, GSX (40-Gallon Short) SERIES 202/203
06/09 316876-000
2
SERVICE HANDBOOK
Your safety and the safety of others is extremely important in the servicing of this water heater. Many safetyrelated 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.
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 this handbook, please contact the Technical Information Center listed on
the cover of this handbook for further assistance. Additional information is also available on the web site listed on
the 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 recommend that on every service call an inspection & cleaning of the base ring fi lter
and fl ame arrestor be performed. See page 19.
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
• 11/16 inch – 6 point – socket – for anode removal
• electrical multimeter (with alligator leads)
• digital or analog manometer
• gas pressure gauge
• water pressure gauge
• thermometer
• tubing cutter if pilot tube is to be replaced
• hose – to drain tank
• container – to measure gallons per minute flow
Digital manometer shown.
3
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.
Read instruction manual before
installing, using or servicing
water heater.
TROUBLESHOOTING QUICK REFERENCE
IMPORTANT: Before performing any test, check the area around the water heater for any source of a flammable
vapor (i.e gasoline, paint thinners, etc.) If any sources are found do not proceed until they are removed.
PROBLEM POSSIBLE CAUSE TEST / CORRECTIVE ACTION
NO HOT WATER:
INSUFFICIENT HOT
WATER:
Insuffi cient Combustion Air or Venting
Issues – combustion chamber thermal
cut off tripped.
Pilot will not light Check gas supply/Bleed air from gas line/turn
Pilot will not remain lit when top gas
control knob is released
Burner will not light or remain lit. Low gas pressure – check as described on p
Water heater improperly sized to meet
hot water demands
Follow the steps on pp 18 – 19. Always check
and clean the base ring fi lter and the fl ame
arrestor.
gas on.
Test thermocouple and gas control valve/
thermostat as described on pp 20-21.
18. Insuffi cient combustion air – follow steps
on pp 18 -19.
Compare hot water requirements with the
capacity of the water heater. See sizing guide
on p. 25. You may also use the volume test
on page 34 to analyze your hot water needs.
If necessary, install a water heater with greater
capacity.
WATER LEAKAGE:
Gas Control Valve/Thermostat set
too low
Sediment or lime in the tank Drain (p. 17). Determine if water treatment is
Condensation Adjust the thermostat setting (p 24).
Dripping Temperature & Pressure Relief
Valve
5
Turn temperature dial to desired temperature
as described on p. 24
needed (p. 29).
Check water supply pressure.
In closed systems, the supply pressure should
not exceed 80 psi (in a 24 hour cycle). If the
pressure exceeds 80 psi, install a pressure
reducing valve in combination with a properly
sized thermal expansion tank (pp. 35-36 & 37).
PROBLEM POSSIBLE CAUSE TEST / CORRECTIVE ACTION
WATER LEAKAGE:
Thermostat does not shut-off Check the Gas Control Valve/Thermostat as
described on p. 20-21.
Drain valve dripping/leaking Back fl ush to clean- out sediment, replace if
necessary
Tank Leak Check Leakage Checkpoints described on
p. 25.
6
TABLE OF CONTENTS
BASIC INSTALLATION ...................................................................................................................................... 8-16
DRAINING AND FILLING THE WATER HEATER ..................................................................................................17
Draining the Water Heater ................................................................................................................................17
Filling the Water Heater ....................................................................................................................................17
CHECKING THE GAS SUPPLY FOR PRESSURE ................................................................................................18
CHECKING FOR SUFFICIENT COMBUSTION AIR OR VENTING ISSUES .................................................. 18-19
Combustion Air Test ..........................................................................................................................................18
Draft Test ...........................................................................................................................................................19
External Inspection & Cleaning of the Base Ring Filter ....................................................................................19
Cleaning the Combustion Chamber and Flame Arrestor ..................................................................................19
TESTING THE THERMOCOUPLE AND GAS CONTROL VALVE/THERMOSTAT ...............................................20
Thermocouple Output Test ................................................................................................................................20
Gas Control Valve/Thermostat (Thermal Switch Models) .................................................................................20
REPLACING THE THERMOCOUPLE AND GAS CONTROL VALVE/THERMOSTAT ................................... 21-23
Removing the Manifold/Burner Assembly .........................................................................................................21
Removing the Burner from the Manifold/Burner Assembly ...............................................................................21
Replacing the Thermocouple ............................................................................................................................21
Replacing the Manifold/Burner Assembly .........................................................................................................22
Removing and Replacing the Gas Control Valve/Thermostat ...........................................................................23
ADJUSTING THE TEMPERATURE ON THE GAS CONTROL VALVE/THERMOSTAT .......................................24
GAS WATER HEATER SIZING GUIDE ..................................................................................................................25
LEAKAGE CHECKPOINTS ....................................................................................................................................25
TECHNICAL SERVICE BULLETINS ................................................................................................................ 26-38
Water Hammer ..................................................................................................................................................27
Mineral Buildup .................................................................................................................................................28
Aluminum Hydroxide .........................................................................................................................................29
Condensation ....................................................................................................................................................30
Discolored Water ...............................................................................................................................................31
Smelly Water .....................................................................................................................................................32
Chlorination Procedure .....................................................................................................................................33
Not Enough Hot Water ......................................................................................................................................34
Thermal Expansion ..................................................................................................................................... 35-36
Leaking Temperature and Pressure Relief Valve ..............................................................................................37
Insulation Blanket ..............................................................................................................................................38
GENERAL INFORMATION ............................................................................................................................... 39-40
7
s
BASIC INSTALLATION & OPERATION
INSTALLATION OF RESIDENTIAL GAS WATER HEATER
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
Exhaust Vent to
Ouside of Building
Union
Gas Supply
Water
Water
Shut-Off
Valve
Temperature-Pressure Relief Valve
with discharge piped to an
adequate drain. Do not cap or plug.
Manual Gas
Shut-off Valve
Supply- Cold*
*Massachusett: Install
a vacuum relief in cold
water line per section
19 MGL 142.
Expansion Tank
Pressurize 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
Gas Control Valve/Thermostat
Recommended setting of 120°F.*
Do not cap or plug.
6” Maximum Air Gap
NOTE: Local codes
Union
may vary.
Sediment Trap
(Drip Leg) 3” Minimum.
Drain
Metal Drain Pan piped to an adequate drai
Air is drawn in for combustion.
Keep area clean and free from
flammables and flammable vapors.
NOTE: Drain pan diameter must be at lea
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.
** White-Rodgers® gas control valve/thermostat shown in this figure. The valve may vary according to model and year.
Figure 1
8
BASIC INSTALLATION & OPERATION
This portion of this handbook applies to the Operations and Servicing of Residential Gas, Tank Type, Water
Heaters, which are vented atmospherically and use a thermocouple as their electrical source.
Control: There are two gas control valve/thermostat confi gurations available. Both valves have similar control
elements such as the Gas Control Knob & Water Temperature Dial. Both valves have high water temperature limit
safety. Please note the location of the control elements on the following fi gures.
Foam Fill
Hole
Anode Rod
Hot Water
Outlet
Flue Baffle
Reset
Button
Gas
Supply
- Inlet
Draft Hood
Gas Control Knob
On|Pilot|Off
Cold Water
Inlet
Jacket
Anode
Rod
Flue
Tube
Temperature Probe
/High Limit Probe
Gas Control Knob
Off|Pilot|On
Gas Supply- Inlet
Draft Hood
Temperature-Pressure
Relief Valve
Dip Tube
Flue Baffle
Gas Control Valve
/Thermostat
Drain Valve
Robertshaw®
Gas Control Valve/
Thermostat
Water
Temperature
Dial
**Manifold Gas
Pressure Tap
*NOTE: Some models do not have thermal switch wire leads as shown in this figure.
** Manifold Gas Pressure Taps are located on the underside of the gas control valve/thermostat.
Setting Indicator
(Index Bar)
Water
Temperature
Dial
Thermal Switch
Wire Leads
with Connectors
(some models)*
White-Rodgers®
Gas Control Valve/
**Manifold Gas
Pressure Tap
Figure 2
9
Thermostat
BASIC INSTALLATION & OPERATION
Burner/Manifold Door Assembly: The burner/manifold assembly consists of several components such as:
main burner, burner orifi ce, manifold tube, pilot burner, pilot orifi ce, pilot tube, igniter, and thermocouple. See the
fi gure below for the complete list of components.
The pilot burner remains on once it is manually lit. When incoming cold water activates the thermostat, gas fl ows
to the main burner. The pilot fl ame ignites this gas. The main fl ame burns until the tank reaches set temperature
then the thermostat interrupts this main gas fl ow.
Figure 3
Pilot Tube
Manifold Tube
TCO (Thermal Cut
Off) Switch
TCO Reset
Button
Front View
Door Gasket
Igniter Wire
Manifold Door
Burner Orifice*
View Port
TCO (Thermal Cut
Off) Sensor
*DO NOT operate the water heater without the pilot and burner orifices installed.
Main Burner
Pilot (Burner)
Thermocouple
Burner Screws
Normal Operation
Pilot: The pilot fl ame heats the end of a thermocouple.
As the thermocouple gets hotter, it generates a small
(cannot be detected without an electrical meter)
electrical current to the bottom of the gas control valve/
thermostat. This current powers the electromagnet
and holds open the main gas interrupter as long as the
pilot fl ame is heating the thermocouple. The normal
voltage for a properly working thermocouple is between
20 and 30 mv. DANGER! If the pilot is extinguished,
it can take up to 180 seconds for the thermocouple to
cool suffi ciently to close the safety valve.
Pilot Bracket
Igniter Wire
Figure 4
Safety Valve
Safety Valve
Pilot Assembly View
Pilot (Burner)
Pilot Orifice*
Ferrule
Pilot Nut
Reset
Button
Piezo Igniter Tip
NOTE: The base of the
Thermocouple must be
flush with the base of
the pilot bracket.
Thermocouple
Pilot Tube
Gas Control Knob
10
Pilot
Flame
RobertShaw Gas Control Valve/Thermostat Shown.
BASIC INSTALLATION & OPERATION
Energy Cut Off (ECO): A metal tube (Temperature
Probe) mounted onto the back of the gas control
valve/thermostat is immersed inside the tank water.
Figure 5
Gas Control Knob
Reset Button
The probe acts as a temperature high limit. If water
gets excessively hot, an Energy Cut Off (ECO) switch
within the probe opens, interrupting the small electrical
current to the gas valve, and gas fl ow through the
Protective
Plastic Sleeve
Temperature
Probe
Gas Inlet
control is interrupted. NOTE: If this safety sensor opens,
the entire control must be replaced. The ECO is NOT
resettable.
Thermal Cut Off Switch (TCO): The water heater
is also equipped with a resettable thermal switch,
Temperature
Sensor
ECO
designed to shut off the gas supply in the event the
water heater has been exposed to high combustion
chamber temperatures caused by fl ammable vapors
(e.g. spilled gasoline), poor combustion caused by a
blocked vent or insuffi cient combustion air.
Gas: When you prepare to light the pilot, you are
instructed to turn the gas control knob to the pilot
Gas Control Valve/Thermostat - Side View
NOTE: RobertShaw® Gas Control
Valve/Thermostat shown.
Thermocouple
TCO (Thermal
Cut O) Sensor
TCO (Thermal
Cut O) Switch
TCO Reset
Button
position and depress the gas control knob (Reset button
on Robertshaw Gas Valves). When depressed gas will
fl ow to the pilot burner only. You then have to (manually)
ignite this pilot gas using the piezo igniter button. When the pilot is lit, the fl ame must heat the thermocouple until
it generates suffi cient voltage to the gas valve to allow you to release the knob while gas continues to fl ow to
the pilot. When the gas control knob is turned to the “ON” position, gas is also available to the main burner if the
thermostat calls for heat.
Water Flow: When a hot water faucet is opened, water pressure from the well tank or street main forces cold
water into the water heater through the dip tube. This pushes hot water out of the tank.
11
BASIC INSTALLATION & OPERATION
Thermostat Operation: Standard residential water heaters use mechanical thermostats. With a mechanical
thermostat, a dial setting of 120° F may shut the burner down at a tank temperature between 110° and 130° F.
The heater will consistently shut off at this same temperature. For this same reason, water temperature may drop
15° F - 25° F, around the temperature probe, before the main burner is activated. Keep in mind that hot water in
the upper part of the tank will probably be very near the “shut off” temperature of the control while incoming cold
water drops the water temperature around the thermostat probe. Also short, repeating heating cycles caused by
small hot water uses can cause temperatures at the point of use to exceed the thermostat setting by up to 30° F.
Gas Control Knob
On|Pilot|Off
Reset Button
130°F
140°F
150°F
Robertshaw®
Gas Control Valve/
Thermostat
Note: Temperature marks noted above are approximate and may vary due to various factors.
120°F Mark
Water
Temperature
Dial
White-Rodgers®
Gas Control Valve/
Thermostat
Gas Control Knob
Off|Pilot|On
Water Temperature Time to Produce 2nd & 3rd
Degree Burns on Adult Skin
160°F (71°C)
About 1/2 second
150°F (66°C) About 1-1/2 seconds
140°F (60°C) Less than 5 seconds
130°F (54°C) About 30 seconds
120°F (49°C) More than 5 minutes
80°F (27°C) - - - - - - - - - - - - - - - -
130°F
140°F
150°F
Figure 6
12
BASIC INSTALLATION & OPERATION
T
Combustion Air Requirements:
WARNING
Carbon Monoxide Warning
Water heater must be vented to outdoors.
Vent must be installed by a qualified technician using
the 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, and/or the
installation instructions.
Examples of a qualified technican include: gas
technicians, authorized gas company personel, and
authorized service persons.
Failure to so do can result in death or carbon monoxide
poisoning.
Table 1:
BTUH Input
30,000 188 9 x 21
45,000 281 14 x 20
60,000 375 15 x 25
75,000 469 15 x 31
90,000 563 20 x 28
105,000 657 20 x 33
120,000 750 25 x 30
135,000 844 28 x 30
Minimum Square
Feet with
8’ Ceiling
Typical Room
with 8’ Ceiling
IMPORTANT:
• The area must be open and be able to provide
the proper air requirements to the water heater.
Areas that are being used for storage or contain
large objects may not be suitable for water heater
IMPORTANT: Air for combustion and ventilation must
not come from a fl ammable or corrosive atmosphere.
Any failure due to fl ammable or corrosive elements in
the atmosphere is excluded from warranty coverage.
The following types of installation (not limited to the
following) will require outdoor air for combustion due to
chemical exposure and may reduce but not eliminate
the presence of corrosive chemicals in the air:
• beauty shops
• photo processing labs
• buildings with indoor pools
• water heaters installed in laundry, hobby, or craft
rooms
• water heaters installed near chemical storage areas
• water softeners
Combustion air must be free of acid-forming chemicals
such as sulfur, fl uorine, and chlorine. These elements
are found in aerosol sprays, detergents, bleaches,
cleaning solvents, air fresheners, paint, and varnish
removers, refrigerants, and many other commercial
and household products. When burned, vapors from
these products form highly corrosive acid compounds.
These products should not be stored or used near the
water heater, air inlet, or air intake path.
installation.
• Water heaters installed in open spaces in buildings
with unusually tight construction may still require
outdoor air to function properly. In this situation,
outside air openings should be sized the same as
for a confined space.
• Modern home construction usually requires
supplying outside air into the water heater area.
• Room exhaust fans may effect air requirements.
Confi ned Space: For the correct and proper operation
of this water heater, ample air must be supplied for
the combustion, ventilation, and dilution of fl ue gases.
Small enclosures and confi ned areas must have two
permanent openings so that suffi cient fresh air can be
drawn from outside of the enclosure. One opening shall
be within 12 inches of the top and one within 12 inches
of the bottom of the enclosure.
The size of each opening (free area) is determined by
the total BTUH input of all gas utilization equipment
(i.e., water heaters, furnaces, clothes dryers, etc.) and
the method by which the air is provided. The BTUH
input can be found on the water heater rating plate.
Additional air can be provided by two methods:
1. All air from inside the building.
2. All air from outdoors.
12” MAXIMUM
Combustion and ventilation air requirements are
determined by the location of the water heater.
The water heater may be located in either an open
(unconfi ned) area or in a confi ned area or small
enclosure such as a closet or small room. Confi ned
spaces are areas with less than 50 cubic feet for
each 1,000 BTUH of the total input for all gas-using
appliances.
PERMANENT
OPENINGS TO
HE OUTSIDE OR
ADDITIONAL
ROOMS WITHIN
THE BUILDING
CLOSET
OR
OTHER
CONFINED
SPACE
Unconfi ned Space: A water heater in an unconfi ned
space uses indoor air for combustion and requires at
least 50 cubic feet for each 1,000 BTUH of the total
input for all gas appliances. The table below shows a
few examples of the minimum square footage (area)
required for various BTUH inputs.
12” MAXIMUM
Figure 7
13
BASIC INSTALLATION & OPERATION
All Air from Inside the Building: When additional air
is to be provided to the confi ned area from additional
room(s) within the building, the total volume of the
room(s) must be of suffi cient size to properly provide
the necessary amount of fresh air to the water heater
and other gas utilization equipment in the area. Each
of the two openings shall have a minimum free area of
1 square inch per 1,000 BTUH of the total input rating
of all gas utilization equipment in the confi ned area, but
not less than 100 square inches for each opening.
CONFINED
SPACE
PERMANENT
OPENINGS
1 SQUARE
INCH/1000
BTUH
(MINIMUM
100 SQ. IN.
FOR EACH
OPENING)
Figure 8
Minimum Free Area of Permanent Openings for
Ventilation and Combustion Air Supply - All Air from
Outdoors Only.
Based on total BTUH input rating for all utilizing
equipment within the confi ned space.
Opening Source
Per Opening (sq. in.)
*D ire ct to o utd oor s 1 sq. in, per 4000 BTUH Fi gu re 9
Ver tic al Du cts 1 sq. in, per 4000 BTUH Fi gu re 10
Ho riz ont al Du cts 1 sq. in, per 2000 BTUH Fi gur e 11
Si ngl e Ope nin g 1 sq. in, per 3000 BTUH Fi gu re 12
Example: A water heater with an input rating of 50,000 BTUH
using horizontal ducts would require each opening to have a
minimum free area of 25 square inches.
Minimum free area = 50,000 BTUH x 1 sq. in. / 2000 BTUH = 25
sq. in.
These openings connect directly with the outdoors
*
Minimum Free Area
Reference
Drawing
through a ventilated attic, a ventilated crawl space, or
through an outside wall.
Consult the local codes of your area for specific
ventilation and combustion air requirements
ABLE VENT
TO OUTDOORS
INSTALL ABOVE
INSULATION
All Air from Outdoors: Outdoor fresh air can be
provided to a confined area either directly or by the use
of vertical and horizontal ducts. The fresh air can be
taken from the outdoors or from crawl or attic spaces
that freely communicate with the outdoors. Attic or
crawl spaces cannot be closed and must be properly
ventilated to the outside.
Ductwork must be of the same cross-sectional area
as the free area of the opening to which they connect.
The minimum dimension of rectangular air ducts
cannot be less than three inches.
The size of each of the two openings is determined by
the method in which the air is to be provided. Refer to
the table below to calculate the minimum free area for
each opening.
Louvers and Grilles: In calculating free area for
ventilation and combustion air supply openings,
consideration must be given to the blocking effect of
protection louvers, grilles, and screens. These devices
can reduce airflow, which in turn may require larger
openings to achieve the required minimum free area.
Screens must not be smaller than 1/4” mesh. If the
free area through a particular design of louver or grille
is known, it should be used in calculating the specified
free area of the opening. If the design and free area
are not known, it can be assumed that most wood
louvers will allow 20 - 25% of free area while metal
louvers and grilles will allow 60 - 75% of free area.
Louvers and grilles must be locked open or
interconnected with the equipment so that they are
opened automatically during equipment operation.
Keep louvers and grilles clean and free of debris or
other obstructions.
CONFINED
SPACE
ALTERNATE
AIR INLET
1 SQ. INCH PER
100 SQ. INCH MINIMUM (EACH)
ALL AIR FROM OUTDOORS: INLET AIR FROM VENTILATED
4000 BTUH
CRAWL SPACE/OUTLET AIR TO VENTILATED ATTIC
OUTLET
ATTIC 1 SQ.
INCH PER
4000 BTUH
INLET AIR FROM
THE CRAWL SPACE
FOUNDATION
Figure 9
GABLE VENT
TO OUTDOORS
INSTALL ABOVE
INSULATION
OUTLET AIR TO
CONFINED
SPACE
ALL AIR FROM OUTDOORS THROUGH VENTILATED ATTIC
ATTIC 1 SQ. INCH
PER 4000 BTUH 100 SQ. INCH MIN.
(EACH)
INLET AIR DUCT
1 SQ. INCH PER
4000 BTUH - 100
SQ. INCH MIN.
(EACH)
Figure 10
AIR TO
OPEN
VENT
12” MAXIMUM
14
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