Pilot lights okay, but burner won't turn on

Edwinjcb

I just installed a gas valve on a wall heater. Robert Shaw 710 502. I can get the pilot to light just fine, but can't get the main burner to fire up. It was working on the old valve, unit it wore out on me. The Robert Shaw is a used valve which I'm told was working when it was removed. Wiring appears correct. The fact the pilot light works leads me to believe the thermopile is okay. Any ideas from anyone? Otherwise, I'm going to conclude the gas valve is bad.

Fred

Did you turn the main power switch back on? Is there a tiny switch on the gas valve itself that is switched off? What brand/model is the heater?

lchmb

check your millivolts prior to condemning the valve.

Edwinjcb

there is no tiny switch on the gas valve. I'm jumping the two screws at the thermostat, which eliminates a possibly bad thermostat. where do I check the millivolts? on the thermopile? Is it possible the thermopile is bad so it's preventing the gas valve from sending gas to the burners?

Tim McElwain

Is this a 750 millivolt system? If it is then you need to do a complete diagnosis.

Tim McElwain

Go to before you ask and click the second "here" and look for my ugly face the procedure for checking millivolts is there.

Abracadabra

Is the knob on the gas valve turned to "ON" position and not the "Pilot" position?

j a_2

Used gas valve? Not a real good idea....jmo....