GBT A2-035, Installation & Operating Instructions Manual

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14. Turn the operating thermostat to its lowest setting so that water pump stops.
START-UP
1. Slowly turn on the manual gas valve upstream of the heater/boiler. For A2-035 and 050 models only,
turn on the manual valve located on top of the Robertshaw automatic gas valve.
2. Turn the operating thermostat to a setting high enough to turn on the water pump.
3. The ignition control module will turn on the spark ignition system and pilot operating valve to light the
pilot burner. If the pilot does not light the first time, it will retry, up to three times. This is normal during
the initial start-up due to air in the pilot line. If, after trying three times, the pilot burner does not light,
remove power to the ignition module to reset, by either turning the operating thermostat down to its
lowest setting or turning off electrical power to the heater/boiler.
NOTE: CSD-1 models only utilize an ignition module that waits 5 minutes before attempting to
re-light the pilot.
4. After the pilot burner is lit and pilot flame is proven, the Ignition Module will open the automatic main gas
valve(s) and the main burner will light.
If the pilot or main burner fails to light after repeated attempts, shut off the
manual gas valve upstream of the heater/boiler, remove electrical power from
the heater/boiler, and call your qualified service technician or gas supplier.
5. Check for gas leaks in the gas train assembly using soap and water or an appropriate leak check fluid.
DO NOT use an open flame to check for gas leaks.
6. Using the manometers with the heater/boiler operating, check to make sure the gas supply pressure is
within the limits shown above.
7. Check the manifold gas pressure downstream of the automatic gas valves using the outlet pressure tap
provided on the gas valve (A2-035 and 050 models only) or the pressure tap provided in the gas piping.
•
For Natural Gas models, the manifold pressure should be set to 4.0” water column.
•
For Propane Gas models, the manifold pressure should be set to 10.5” water column.
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For 2-Stage models, see the Operating Section for setting the gas manifold pressure.
a. For A2-035 and A2-050 models, adjust the manifold pressure using the adjustment screw
located on top of the Robertshaw gas valve (remove the dust cover cap to expose the
adjustment screw).
b. For A2-070, 970, 120 and 140 models, adjust the manifold pressure using the Maxitrol gas
pressure regulator located upstream of the automatic gas valve (remove the dust cover cap to
expose the adjustment screw).
c. Replace the manifold pressure adjustment screw caps
8. With the manifold gas pressure set per step 6 above, observe the main burner flame characteristics.
The burner flame should be blue at the base, with yellow at the tips permissible. An excessive amount
of yellow flame suggests a lack of combustion air or inadequate vent draw.