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The combination thermostat/gas valve is a non repairable device. If trouble shooting has determined a problem with the
combination thermostat/gas valve, it must be replaced.
If the burner and/or pilot do not function, service checks for gas pressure, thermocouple output, magnet assembly and
ECO are to be performed. If these check OK, the combination thermostat/gas valve may be faulty.
MANIFOLD PRESSURE TESTING
(this procedure assumes a maximum line pressure of 14.0" w.c.)
Step 1. Set combination thermostat/gas valve to “OFF” position.
Step 2. Remove pressure tap plug (3/16" Allen wrench) and install
pressure tap (7/16 wrench)
Step 3. Connect manometer to pressure tap.
Step 4 Follow lighting instructions and proceed to light
main burner and observe manometer reading.
Step 5 Proper operating range for natural gas is 4.0 ±0.3" W.C.
Proper operating range for L.P. gas is 10.0 ±0.5" W.C.
Step 6 If pressure is OK, set combination thermostat/gas valve to “OFF”
remove manometer and pressure tap and replace pressure tap plug. Check for gas leaks before placing water
heater back in operation. If pressure is out of the specification noted in step 5, proceed to step 7 or 8 for proper
service procedure.
Step 7 For White Rodgers control, the manifold pressure is not adjustable. If manifold pressure is outside the range
in step 5, the control must be replaced.
Step 8 For Robertshaw control, the manifold pressure is adjustable, proceed to step 9 for adjustment procedure
Step 9 While burner is in operation, remove regulator access cap to expose the regulator adjusting screw. With small
screw driver, rotate adjusting screw clockwise to increase pressure and counter clockwise to decrease pressure.
Step 10 Replace regulator access cap, set combination thermostat/gas valve to “OFF”. Remove manometer and
pressure tap and replace pressure tap plug. Check for gas leaks before placing water heater back in operation.
LINE PRESSURE
The combination thermostat/gas valve is designed for a maximum line pressure of 14.0" w.c. and a minimum line
pressure of 1.0"w.c. over the water heater rated manifold pressure. Line pressure must be checked with burner on and
burner off to assure proper readings.
Pressure Tap
Shown Installed
Combination Thermostat/Gas Valve Testing and Replacement
SERVICE PROCEDURE RG-V
Combination Thermostat/Gas Valve Testing
and Replacement