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37C72U  
Water Heater Thermostat Control  
Installation Instructions  
WHITE-RODGERS  
(Left-Hand Outlet Thread Model)  
FOR LP GAS ONLY  
RETAIN INSTRUCTIONS FOR FUTURE REFERENCE.  
FOR YOUR SAFETY  
“WHAT TO DO IF YOU SMELL GAS”  
• Do not try to light any appliance.  
• Do not touch any electrical switch; do not use any  
phone in your building.  
• Immediatelycallyourgassupplierfromaneighbor’s  
phone. Follow the gas supplier’s instructions.  
• If you cannot reach your gas supplier, call the fire  
department.  
WARNING  
!
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Do not use this LP Gas control on a Natural Gas  
water heater. Improper operation could occur, re-  
sulting in personal injury and/or death due to Car-  
bon Monoxide poisoning, fire, or explosion. Check  
for proper gas type as listed on the rating plate  
affixed to the water heater.  
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C A U T I O N :  
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NOTE  
Fixed Adjustment Main and Pilot Regulators  
This gas control is equipped with LEFT-HAND threads in  
the outlet for use on LP gas water heaters where the  
connection between the gas control and the main burner  
manifold are with LEFT-HAND threads.  
The main and pilot gas regulators require no field  
service. They automatically control and maintain the  
outlet main and pilot burner gas pressure.  
FAILURE TO READ AND FOLLOW ALL INSTRUCTIONS BEFORE INSTALLING OR OPERATING THIS  
CONTROL COULD CAUSE PROPERTY DAMAGE, PERSONAL INJURY AND/OR DEATH.  
1. This control must be installed or serviced only by a  
professional.  
7. In some situations, the gas may lose its odor. To detect  
unodorized gas, you must have a gas detector which  
canbepurchasedfromyourgascompany. Ifyoudonot  
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.  
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 posi-  
tion. The mechanism is damaged and the control must  
be replaced. Shut off gas to the water heater.  
8. Ifanyproblemsorquestionsareencounteredaboutthe  
safe use of LP gas, contact your local gas supplier.  
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.  
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. LP gas is heavier than air. Leaking gas will settle near  
the ground and will tend to accumulate.  
6. 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.  
WHITE-RODGERS DIVISION  
EMERSON ELECTRIC CO.  
9797 REAVIS ROAD  
ST. LOUIS, MISSOURI 63123-5398  
PART NO. 37-6093A  
Printed in U.S.A.  
9912  
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INSTALLATION  
REPLACEMENT INFORMATION  
Gas supply  
pipe  
REMOVING OLD CONTROL  
1. Shut off gas to water heater.  
2. Shut off water at cold water inlet.  
3. Connect hose to heater drain cock. Drain water to a  
nearby drain. Open a hot water faucet for faster drain-  
ing.  
Gas shut-off  
valve  
4. Disconnect gas line at union (figure 1). Remove piping  
from old control.  
Union  
(metal-to-metal)  
5. Disconnect the:  
a. Thermocouple (left side).  
b. Pilot burner (small tube on the right side)  
c. Main burner (large tube in the middle).  
6. Remove the control by turning it counterclockwise  
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C A U T I O N :  
B
Drip leg  
(sediment trap)  
A
(
). If needed, a short piece of 1/  
” black iron pipe  
2
can be screwed into the control inlet to increase lever-  
age.  
To pilot  
burner  
Pipe cap  
SPECIAL INSTALLATION NOTE  
To main burner  
To thermocouple  
If replacing a Unitrol or Robertshaw control, install exten-  
sion adaptor fitting provided into the outlet of the control.  
Figure 1. Typical gas connection  
INSTALLING NEW CONTROL  
All piping must comply with local and state ordinances or  
with the National Fuel Gas Code (ANSI Z223.1–NFPA 54),  
whichever applies.  
4. Connectgasline.Usenewblackironpipethathasbeen  
properly reamed. If old pipe is used, be sure it is clean  
and free from rust and scale. Use pipe joint compound  
on male threads only. (Use a pipe joint compound  
approved for natural gas service.) Do not use TEFLON  
tape. Do not apply compound to first two threads.  
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  
leading to the control.  
5. DO NOT use joint compound or tape on the union  
connection.  
1. Apply pipe joint compound to the male threads of  
control, leaving the first two or three threads clean.  
6. To fill the water heater with water:  
2. Install control in tank. Turn clockwise (  
). Use a  
a. Close the water heater drain valve by turning the  
handle to the right (clockwise). The drain valve is on  
the lower front of the water heater.  
shortpieceofpipetohelpinturning. Alignthecontrolso  
that burner and pilot tubes may be connected.  
b. Open the cold water supply valve to the water  
heater.  
NOTE  
This control is equipped with LEFT-HAND threads on the  
outlet of the control. Check the fitting on the burner assem-  
bly to make sure the threads are also the LEFT-HAND type.  
If the threads are not LEFT-HAND type, return the control to  
the dealer and obtain an LP gas control with RIGHT-HAND  
threads on the outlet.  
NOTE  
The cold water supply valve must be left open  
when the water heater is in use.  
c. To ensure complete filling of the tank, let air exit by  
openingthenearesthotwaterfaucet. Allowwaterto  
run until a constant flow is obtained. This will let air  
out of the water heater and the piping.  
3. Make burner, pilot, and thermocouple connections. Do  
not use pipe joint compound or teflon tape. Thermo-  
couplenutshouldbehandtightenedandthenturnedan  
additional 1/  
TIGHTEN.  
4
turn with a small wrench. DO NOT OVER-  
d. Check all new water piping for leaks. Repair as  
needed.  
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d. Recheck for leaks.  
CAUTION  
!
e. Rinse off soapy solution and wipe dry.  
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.  
WARNING  
!
DO NOT USE OPEN FLAME OR ANY KIND OF  
SPARK TO CHECK FOR LEAKS. Serious injury or  
death from fire or explosion could result.  
7. Open gas shutoff valve.  
8. BEFORE LIGHTING THE PILOT, CHECK THE GAS  
LINES FOR LEAKS:  
9. Affix the new Lighting Instruction label on the water  
heater to cover the existing label.  
a. Use a soapy water solution. DO NOT test for gas  
leaks using a match or open flame.  
NOTE  
b. Brush the soapy water solution on all gas pipes,  
joints, and fittings.  
The rating plate must be left visible for future reference.  
c. Check for bubbling soap. This means you have a  
leak. Turn OFF the gas and make the necessary  
repairs.  
TO LIGHT APPLIANCE  
1. Set control to lowest setting by turning the water tem-  
6. Turn gas control knob counterclockwise  
to “PILOT”.  
perature dial clockwise (  
) to the “PILOT LIGHT-  
ING” position. DO NOT FORCE.  
7. Depress control knob all the way and hold down.  
Immediately 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.  
GAS  
CONTROL  
KNOB  
TEMPERATURE  
POINTER  
If knob does not pop up when released, turn knob  
clockwise to “OFF”. STOP and immediately call  
your service technician or gas supplier.  
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WATER  
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TEMPERATURE  
DIAL  
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CAUTION:  
If the pilot will not stay lit after several tries, turn gas  
control knob to “OFF” and call your service techni-  
cian or gas supplier.  
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RISK OF SCALDING  
INCREASES WITH  
HOTTER WATER  
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8. Replace inner and outer burner doors.  
Figure 2. Gas Control Knob and  
Water Temperature Dial  
9. At arm's length away, turn gas control  
knob counterclockwise to the full “ON”  
position.  
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2. Turn gas control knob clockwise to “OFF”.  
10. Align the water temperature dial mark ( ) with the  
temperature pointer on the cover. This mark, indicative  
of approximately 120°F, is the preferred starting point.  
If hotter water is desired, see TEMPERATURE REGU-  
LATION on page 4.  
NOTE  
Gas control knob must be depressed slightlyto turn  
from "PILOT" to "OFF". Do not use tools or exces-  
sive force.  
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.  
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.  
4. Remove inner and outer burner doors located on the  
water heater under gas control unit.  
5. Find pilot - follow small metal  
tubes from gas control. The  
pilot is located near the main  
PILOT  
THERMO-  
burner.  
BURNER COUPLE  
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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.  
To avoid scald injury, set the control at the lowest setting  
which will still deliver your needed hot water.  
WARNING  
!
The recommended water temperature dial setting is at the  
arrow ( ). The water temperature out of the heater at this  
setting will be approximately 120°F.  
The hotter the water the greater the risk of scald  
injury and the shorter the time to cause injury.  
If you use hot water frequently and in short spurts, water  
temperature can occasionally exceed the temperature set-  
tingbyupto30°Fbecauseofthedynamicsoftheappliance.  
APPROXIMATE  
TEMPERATURE  
(°F)  
APPROXIMATE  
TIME TO  
CAUSE INJURY  
SETTING  
(
)
120° ±10°  
130° ±10°  
140° ±10°  
150° ±10°  
160° ±10°  
5 Minutes  
30 Seconds  
5 Seconds  
A
B
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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.  
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WATER  
TEMPERATURE  
DIAL  
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CAUTION:  
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RISK OF SCALDING  
INCREASES WITH  
HOTTER WATER  
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Figure 3. Water Temperature Dial  
The arrow ( ) setting is the safest and most economical. If  
you want hotter water, rotate the water temperature dial  
WARNING  
!
counterclockwise (  
) to a higher setting. Approximate  
Never allow small 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.  
water temperature delivered at the different settings is  
shown in the following table.  
TO TURN OFF GAS TO APPLIANCE  
Set the control to lowest setting by turning water tempera-  
Turn gas control knob clockwise to “OFF”.  
ture 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”.  
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Gas control knob must be depressed slightly. Do not use  
tools or excessive force.  
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Review and leave these instructions with the consumer!