Heat N Glo stand alone natural gas heater pilot won't stay lit when you let off the button???

[QuintonG23]

Backstory: I have a Heat N Glow stand alone (at least 20 years old) heater. I turned off the pilot and gas to clean out the box before I start using it for the season.

Issue: Once the box was cleaned and everything put back in it's place, the pilot light will no longer stay lit when I let go of the button (On/Off/Pilot button).

Troubleshooting: I checked the millivolts at the gas controller, and the thermopile is reading over 350mv (the controller is a thermopile only and has a wire going to where the thermocouple would go, I checked that as well and it's reading over 350mv as well).

Current Conclusion: At this point, I'm afraid I may have to buy a new gas controller.

Anyone have any ideas of what it could be other than the gas controller?

Also, I have a Robertshaw No Turndown Millivolt Controller Thermopile Only installed.

 

[DAKSY]

Can you give the model of your unit?

 

[QuintonG23]

Can you give the model of your unit?

The model is "Bay Stove" and the serial says BYSTN.

 

[DAKSY]

Every manual I can find shows a valve with thermopile AND thermocouple. I don’t remember this model…
Anybody else?

 

[QuintonG23]

Every manual I can find shows a valve with thermopile AND thermocouple. I don’t remember this model…
Anybody else?

I am not the first owner of this fireplace. It is possible that the previous owner swapped out the gas valve. The valve has a wire that goes from the connector of the thermopile to the back of the valve that is presumably where the thermocouple would connect. There is a thermocouple in the unit, but it is not connected to anything and there is no place for it to connect on the valve.