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Robertshaw

 

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The gas control is a non repairable device. If trouble shooting has determined a problem with the gas control, 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 gas control may be faulty.

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Step 1.

Set gas control to “OFF” position.

Step 2.

Remove pressure tap plug and install
pressure tap.

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 gas control 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 gas control to “OFF”. Remove manometer and
pressure tap and replace pressure tap plug. Check for gas leaks before placing water heater back in operation.

LINE 

P

RE

SS

URE

The gas control 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.

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12

Summary of Contents for 25X78B N Series

Page 1: ...lified service providers Models Covered by This Manual GX225S BN GX155S BN 25X78B N 55X80B N M1XR65T BN CX SX MI75S BN CX SX M2XR75S BN CX SX MI100T BN CX SX 65T65 BN CX SX 75T80 BN CX SX C S D W275T...

Page 2: ...Cleaning and Replacement White Rodgers and Robertshaw Gas Control 9 AG II Pilot Assembly Inspection Cleaning and Replacement Honeywell Gas Control 10 AG II Gas Control Testing and Replacement White R...

Page 3: ...lly depress pilot lighting button 4 Clean repair or replace 1 Check connection at gas control Proper tightness should be finger tight plus turn 2 Inspect thermocouple to ensure that it is fully engage...

Page 4: ...as control is powered and waiting for the set point knob to be turned to a water temperature setting Gas control was turned to the OFF position 1 Thermopile failure 2 Unstable pilot 3 Pilot tube block...

Page 5: ...s control is wet or physically damaged See Service Procedure AG III Page 16 Lite pilot per the instructions located on the lighting instructions label or the lighting instructions located in the insta...

Page 6: ...peration manual Step 8 Slide inner door closed when finished SERVICE PROCEDURE AG I Thermocouple Testing and Replacement For Models Using White Rodgers or Robertshaw Gas Control Page 6 Figure 3 For Wh...

Page 7: ...control to operate for three minutes Step 2 Using a multimeter capable of measuring millivolts measure across thermopile connections at the gas control see Figure 6 CLOSED CIRCUIT THERMOPILE TESTING T...

Page 8: ...t using a 7 16 open end wrench Step 6 Install the new thermopile into the pilot bracket and tighten the threads using care not to damage the thermopile lead wires Route new wires through the appropria...

Page 9: ...bly b Remove pilot tube and pilot orifice c inspect pilot orifice for blockage must be cleaned or replaced SERVICE PROCEDURE AG II Pilot Assembly Inspection Cleaning and Replacement For Models Using W...

Page 10: ...pect pilot orifice a Remove 7 16 nut from the bottom of the pilot assembly b Remove pilot tube and pilot orifice c Inspect pilot orifice for blockage must be free from any debris dirt lint dust etc d...

Page 11: ...ombustion chamber door Step 4 Depress the igniter button repeatedly while viewing the spark through the open door of the combustion chamber If there is no spark proceed to Step 5 If there is a spark t...

Page 12: ...efore 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 p...

Page 13: ...trol Step 1 Disconnect thermocouple from gas control Step 2 Connect a thermocouple adaptor BWC P N 239 44642 00 Robertshaw P N 75036 at the thermocouple location in the gas control Step 3 Reconnect th...

Page 14: ...n Step 1 Disconnect thermocouple from gas control Step 2 Using a multimeter capable of measuring Ohms or continuity attach one lead alligator clip to the pilot tube Insert the other lead probe fully i...

Page 15: ...ntrol is turned past proper alignment do not reverse direction to align b Reattach main burner feedline pilot tube and thermocouple to gas control NOTE Feedline nut for natural gas control uses right...

Page 16: ...position and disconnect the thermowell harness from the gas control Step 4 Using a multimeter set to measure Ohms determine the resistance of the thermowell sensor See caution on this page Step 5 Hol...

Page 17: ...er heater tank temperature Example If the temperature of the water is 84 F then the resistance through the sensor would be 8449 see shaded area NOTE Sensor resistance increases as the temperature fall...

Page 18: ...the thermowell from the tank Step 1 Turn the gas control knob to the OFF position Step 2 Turn off and disconnect gas supply piping to the gas control Step 3 Disconnect wire harnesses and burner assem...

Page 19: ...nge with tabs located on the back of the gas control see Figure 36 Figure 36 Gas control tabs Step 4 Carefully push the gas control back onto the thermowell flange Step 5 Install burner assembly and r...

Page 20: ...Main burner should light smoothly from pilot and burn with a blue flame with a minimum of yellow tips Steel burner models have a self adjusting air mixture and do not have an adjustable air shutter C...

Page 21: ...r Operation Inspection Adjustment Cleaning and Replacement Position thermocouple or thermopile and pilot tube BURNER CLEANING Steel Cast Iron Step 1 Slide open or remove inner combustion chamber door...

Page 22: ...llation of burner assembly Step 10 Reinstall burner assembly into combustion chamber reconnect feedline thermocouple or thermopile pilot tube and igniter wire for applicable models to the gas control...

Page 23: ...uld be free of any blockage Any damage such as cracks restriction due to deformation or unintentional holes are not field repairable and the inlet nipple dip tube must be replaced Step 6 Upon completi...

Page 24: ...ent is recommended Step 6 Upon completion of inspection or subsequent replacement reinstall outlet nipple anode into water heater Reconnect plumbing system to outlet nipple anode resume water supply a...

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