White Rodgers 37C73U Thermostat User Manual

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37C73U  
Water Heater Thermostat Control  
Installation Instructions  
FOR NATURAL GAS ONLY  
RETAIN INSTRUCTIONS FOR FUTURE REFERENCE.  
FORYOUR SAFETY  
“WHAT TO DO IFYOU SMELL GAS”  
• Do not try to light any appliance.  
• Do not touch any electrical switch; do not use any  
phone in your building.  
• Immediately call your gas supplier from a neighbor’s  
phone. Follow the gas supplier’s instructions.  
• If you cannot reach your gas supplier, call the fire  
department.  
WARNING  
!
Do not use this Natural Gas control on a LP Gas water  
heater. Improper operation could occur, resulting in  
personal injury and/or death due to Carbon Monoxide  
poisoning, fire, or explosion. Check for proper gas type  
as listed on the rating plate affixed to the water heater.  
Fixed Adjustment Main and Pilot Regulators  
The main and pilot gas regulators require no field service. They  
automatically control and maintain the outlet main and pilot  
burner gas pressure.  
Model  
Main Regulator  
3.5" W.C.  
Pilot Regulator  
4.0" W.C.  
Flange  
1-1/4"  
1"  
Outlet  
Flying Leads  
No Flying Leads  
No Flying Leads  
No Flying Leads  
No Flying Leads  
No Flying Leads  
11" Flying Leads  
37C73U168  
37C73U170  
37C73U171  
37C73U172  
37C73U173  
37C73U174  
42 KBTU/hr  
38 KBTU/hr  
40 KBTU/hr  
40 KBTU/hr  
45 KBTU/hr  
37.5 KBTU/hr  
4.0" W.C.  
4.9" W.C.  
4.0" W.C.  
4.0" W.C.  
2-1/2"  
2-1/4"  
1-1/4"  
1-1/4"  
4.0" W.C.  
4.0" W.C.  
4.0" W.C.  
4.0" W.C.  
5.0" W.C.  
5.0" W.C.  
FAILURETO READ AND FOLLOW ALL INSTRUCTIONS BEFORE INSTALLING OR OPERATINGTHIS CONTROL COULD  
CAUSE PROPERTY DAMAGE, PERSONAL INJURY AND/OR DEATH.  
1. This control must be installed or serviced only by a  
professional.  
2. Do not use force when moving the gas control knob. If you  
cannot turn the knob with hand pressure only, the control  
must be replaced.  
3. Do not use the control if the knob will not “pop up” after  
being depressed while the knob is in the PILOT position.  
The mechanism is damaged and the control must be  
replaced. Shut off gas to the water heater.  
4. For your safety, this control is supplied with tamper  
resistant screws. Do not attempt to repair or adjust the  
control. If you experience problems, replace the control  
immediately. Continuing to use a damaged control  
could result in fire and/or explosion.  
6. In some situations, the gas may lose its odor. To detect  
unodorized gas, you must have a gas detector which can  
be purchased from your gas company. If you do not have a  
detector and have the slightest suspicion that gas may be  
present, get out of the house and call the gas company. DO  
NOT RELY TOTALLY ON YOUR NOSE.  
WARNING  
!
Scald burns occur in under one second with 160° water,  
which this thermostat will deliver if the temperature dial  
is set at “VERY HOT”. Lower settings of the temperature  
dial will reduce the risk of scald and will reduce your  
fuel bill.  
5. An odorant has been added to the gas to help you detect  
it. Before lighting, search for the odor of gas by sniffing at  
floor level around the water heater.  
PART NO. 37-7202A  
1036  
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INSTALLATION  
REPLACEMENT INFORMATION  
Gas supply  
pipe  
REMOVING OLD CONTROL  
1. Turn off gas supply to the water heater at the manual gas  
shut-off valve. This valve is typically located beside the  
water heater.  
2. Locate the gas control valve/thermostat. Before performing  
any maintenance, turn the temperature dial on the gas  
control valve/thermostat to the lowest setting. (See To light  
Appliance Figure 2)  
Gas shut-off  
valve  
Union  
(metal-to-metal)  
3. On the top of the gas control valve turn the gas control  
knob to the “Off” position. (See To light Appliance Figure A)  
P
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NOTE: On the White-Rodgers gas control valve/  
thermostat the knob stop must first be slightly  
depressed before turning the gas control knob.  
D
N
I
G
C
C
A
U
T
I O  
N
:
B
Drip leg  
(sediment trap)  
A
To pilot  
burner  
Pipe cap  
4. Close the cold water inlet valve to the water heater and  
open a nearby hot water faucet.  
5. Connect a hose to the drain valve and terminate it to an  
adequate drain. Open water heater drain valve by turning  
handle counterclockwise to drain water heater tank.  
To main burner  
To thermocouple  
Figure 1. Typical gas connection  
3. If control had an ignitor, transfer the ignitor and bracket  
removed from the old gas control valve to the new one.  
IMPORTANT: DO NOT proceed to the following steps  
until the water heater is completely drained.  
4. Reconnect manifold tube (burner), pilot tube, ignitor  
wire (if present), flying leads (if present), Thermocouple  
nut (thermocouple nut should be hand tightened and  
then turned an additional ¼ turn with small wrench. DO  
NOT OVERTIGHTEN. Do not use pipe joint compound  
or TEFLON tape on manifold, pilot, and thermocouple  
connections.  
5. Reconnect union. DO NOT use joint compound or TEFLON  
tape on union connection.  
6. Close the water heater drain valve by turning the handle to  
the right (clockwise). Open the cold water supply valve to  
the water heater to fill the water heater tank.  
6. On some water heaters, the outer door may need to be  
removed.  
7. If control doesn’t have a piezo ignitor, skip to step (8) or  
disconnect the piezo ignitor wire from the piezo ignitor  
button.  
NOTE:There are two types of ignitors. If you have the  
square ignitor, slide the ignitor bracket backward away  
from the gas valve to remove it. If you have a round  
ignitor, first remove the ignitor from the bracket by  
depressing front and rear holding tabs and lift. Next  
remove ignitor bracket from the gas valve. Keep ignitor  
and bracket.  
NOTE:The cold water supply valve must be left open  
when the water heater is in use.  
Keep the nearby hot water faucet open for 3 minutes after a  
constant flow of water is obtained to purge the lines of any  
excess air. Check all new water piping for leaks. Repair as  
needed.  
8. Disconnect the thermocouple, pilot tube, and manifold  
(burner) tube. Some control may have two wires (flying  
leads) attached to the thermal switch that must be  
disconnected as well.  
9. Disconnect the union joint in the gas piping. Disconnect the  
remaining pipe from the gas control valve/thermostat.  
10. Remove the control by turning it counterclockwise. If  
needed, a short piece of ½” black iron pipe can be screwed  
into the control inlet to increase leverage.  
CAUTION  
!
Never use this water heater unless it is completely filled  
with water.To prevent damage to the tank, the tank must  
be filled with water. Water must flow from the hot water  
faucet before turning ON gas to the water heater.  
INSTALLING NEW CONTROL  
All piping must comply with local and state ordinances or with  
the National Fuel Gas Code (ANSI Z223.1–NFPA 54), which-  
ever applies.  
7. Turn on gas shutoff valve.  
Dirt or contamination in the gas line can block the control from  
operating creating a risk of explosion, injury or death. To protect  
the control from dirt/contamination, a drip leg or sediment trap  
(see Figure 1) must be installed in the piping to the control.  
1. To replace the gas control valve/thermostat, reassemble  
in reverse order. When replacing the gas valve, use a  
short piece of pipe to help turn control. (Clockwise) DO  
NOT OVER TIGHTEN or damage may result. Use an  
approved pipe compound on the threads that screw into  
the tank and to the gas pipe that screw into the gas control  
valve/thermostat. Do not use TEFLON tape. Do not apply  
compound to first two threads on gas pipe.  
WARNING  
DO NOT USE OPEN FLAME OR ANY KIND OF SPARKTO  
CHECK FOR LEAKS. Serious injury of death from fire or  
explosion could result.  
!
8. BEFORE LIGHTING THE PILOT, CHECK THE GAS  
LINES FOR LEAKS. Use a soapy water solution. DO NOT  
test for gas leaks using a match or open flame.  
Brush the soapy water solution on all gas pipes, joints,  
and fittings. Check for bubbling soap indicating you have a  
leak. Turn OFF the gas and make the necessary repairs.  
Recheck for leaks. Rinse off soapy solution and wipe dry.  
2. Reconnect the gas piping to the gas control valve/  
thermostat. Use new black iron pipe that has been properly  
reamed. If old pipe is used, be sure it is clean and free from  
rust and scale.  
9. Affix the new Lighting instruction label on the water heater  
to cover the existing label.  
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TO LIGHT APPLIANCE  
MAIN BURNER  
FIGURE A  
FIGURE B  
FIGURE C  
GAS  
CONTROL  
KNOB  
“OFF” POSITION  
“PILOT” POSITION  
“ON” POSITION  
PILOT  
THERMOCOUPLE  
TEMPERATURE  
POINTER  
FIGURE D  
WATER  
TEMPERATURE  
DIAL  
B. Gas Valve/Thermostat with ignitor.  
1. STOP! Read the safety information on the label.  
2. Set the thermostat to lowest setting (PILOT LIGHT-  
Figure 2. Gas Control Knob and  
Water Temperature Dial  
ING). Turn thermostat dial fully clockwise (  
it stops.  
3. Push the gas control knob down slightly and turn  
) until  
A. Gas valve/thermostat without ignitor (If control has an  
ignitor, proceed to Section B).  
1. Set control to lowest setting by turning the water  
clockwise (  
) to "OFF", see FIGURE A.  
temperature dial clockwise (  
) to the "PILOT  
NOTE: Knob CANNOT be turned from "PILOT" to  
LIGHTING" position. DO NOT FORCE.  
OFF" unless it is pushed down slightly. Do not force.  
2. Turn gas control knob clockwise to "OFF". See  
FIGURE A.  
4. Remove the outer burner door located below the gas  
control.  
NOTE: Gas control knob must be depressed  
slightly to turn from "PILOT" to "OFF". Do not use  
tools or excessive force.  
5. Wait five (5) minuted to clear our any gas. If you then  
smell gas,  
STOP! Follow instructions "What to do  
if you smell gas" on the first page of this instruction  
sheet. If you do not detect gas, continue with the next  
step.  
3. Wait at least five (5) minutes to clear out any gas, and  
then smell around the appliance area. If you smell gas,  
STOP! Follow instructions "What to do if you  
smell gas" on the first page of this instruction sheet. If  
you do not detect gas, continue with the next step.  
6. This unit is equipped with a push button pilot ignitor,  
which is used to light the pilot. Locate the ignitor on the  
gas control.  
4. Remove inner and outer burner doors located on the  
water heater under gas control unit.  
7. Turn gas control knob counterclockwise (  
"PILOT", see FIGURE B.  
) to  
5. Find pilot – follow small metal tubes from gas control.The  
pilot is located near the main burner. See FIGURE D.  
6. Turn gas control knob counterclockwise to "PILOT".  
See FIGURE B.  
8. The pilot is located on the right side of the burner. It  
can be located by looking through the glass view port  
while pressing the piezo ignitor button several times.  
Look for a spark at the pilot location, FIGURE D.  
7. Depress control knob all the way and hold down. Im-  
mediately light the pilot with a match. Continue to hold  
knob down for approximately one (1) minute after pilot  
is lit. Release knob and it will pop back up. Pilot should  
remain lit. If pilot goes out, repeat steps 2, 3, 6 and 7.  
9. Once the pilot has been found, push the gas knob all  
the way down. Immediately press the pilot ignitor but-  
ton rapidly 4 to 5 times. If the pilot will not light, repeat  
step 3 through 9.  
10. Continue to hold the gas control knob down for about  
one (1) minute after the pilot is lit. Release the gas  
control knob and it will pop back up. Pilot should  
remain lit. If it goes out, repeat step 3 through 9. It may  
take several minutes for air to clear the lines before the  
pilot will light.  
If knob does not pop up when released, turn knob  
clockwise to "OFF". STOP and immediately call  
your service technician or gas supplier.  
If the pilot will not stay lit after several tries, turn  
gas control knob to "OFF" and call your service  
technician or gas supplier.  
If the pilot does not pop up when released, stop  
and immediately call your service technician or  
gas supplier.  
8. Replace inner and outer burner doors.  
9. At arm's length away, turn gas control knob counter-  
clockwise to the full "ON" position, FIGURE C.  
If the pilot will not stay lit after several tries, turn  
the gas control knob clockwise (  
and call your service technician or gas supplier.  
11. Once the pilot flame is established replace the outer  
burner door.  
12. At arms length away, turn gas control knob counter-  
) to "OFF"  
10. Align the water temperature dial mark ( ) with the  
temperature pointer on the cover. This mark, indicative  
of approximately 120oF, is the preferred starting point.  
If hotter water is desired, see TEMPERATURE REGU-  
LATION on page 4.  
11. Check for leaks at the pilot and main burner fittings  
on the gas control with the main burner firing. Use a  
soapy water solution. If a leak is detected, turn the gas  
supply off and make repairs.  
clockwise (  
) to "ON". See FIGURE C.  
13. Set the thermostat to desired setting. See TEMPERA-  
TURE REGULATION on page 4.  
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TEMPERATURE REGULATION  
After the gas connections are made, water is in the heater and  
the pilot light is ignited, the control must be set to the desired  
water temperature.  
The recommended water temperature dial setting is at the ar-  
row ( ). The water temperature out of the heater at this setting  
will be approximately 120oF.  
If you use hot water frequently and in short spurts, water tem-  
perature can occasionally exceed the temperature setting by up  
to 30oF because of the dynamics of the appliance.  
WARNING  
!
The hotter the water the greater the risk of scald  
injury and the shorter the time to cause injury.  
APPROXIMATE  
TEMPERATURE  
(F)  
APPROXIMATE  
TIME TO  
CAUSE INJURY  
SETTING  
(
)
120°  
130°  
140°  
5 Minutes  
30 Seconds  
5 Seconds  
A
B
C
150°  
160°  
1.5 Second  
VERY  
HOT  
Under 1 Second  
TEMPERATURE  
POINTER  
Be sure to protect babies and the infirm or others with impaired  
mobility who cannot get out of the hot water quickly. They are  
the people most commonly hurt in scald injuries and in need of  
lower temperature and other protection like supervision, point-of  
-use temperature control equipment or a system mixing valve.  
A point-of-use valve or a system mixing valve can be obtained  
from your plumber.  
WATER  
TEMPERATURE  
DIAL  
Figure 3. Water Temperature Dial  
WARNING  
!
The arrow ( ) setting is the safest and most economical. If  
the want hotter water, rotate the water temperature dial coun-  
Never allow children to use a hot water tap, or to draw  
their own bath water. Never leave a child or impaired  
person unattended in a bathtub or shower. Scald burns  
can result.  
terclockwise (  
) to a higher setting. Approximate water  
temperature delivered at the different settings is shown in the  
following table.  
To avoid scald injury, set the control at the lowest setting which  
will still deliver your needed hot water.  
TO TURN OFF GAS TO APPLIANCE  
Turn gas control knob clockwise to "OFF".  
Set the control to lowest setting by turning water temperature  
dial clockwise (  
) to the "PILOT LIGHTING" position on  
dial (as shown in Figure 3). DO NOT FORCE.  
NOTE  
Turn gas control knob clockwise to "PILOT".  
Gas control knob must be depressed slightly to turn from  
"PILOT" to "OFF". Do not use tools or excessive force.  
White-Rodgers is a division  
of Emerson Electric Co.  
The Emerson logo is a  
trademark and service mark  
of Emerson Electric Co.  

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