I recently purchased a home that has a Western Gravity Furnace (model # 8G-75, BTU input per hour 75000, BTU output 56250 per hour). Originally, the furnace would not work it had a strong pilot, but I could not get it to turn on. Upon further inspection I notice that the thermostat wires were worn and bare in areas. So I rewired and purchased a new thermostat, but still can not get the furnace to work with the thermostat. If I jump the thermostat wires the burners do ignite. So what I don't know is does this mean I have an incompatible thermostat or I do I need a new thermopile pilot generator? Thanks in advance for your help and troubleshooting.

I have had the same problem,
The first thing you need to do is remove the burner and clean it really good. Or if you have a long extension on an air hose, what happens is dust residue blocks good flow through the burner, should fire after that.
If that doesn't work, then you need to purchase a new control valve, they run around 150.00

But when I purchase my duplex, he had two of these units in it. Neither worked, I was told to clean the burners really good. One of them worked after that the other didn't, I tried a new thermostat and that didn't work, so I replaced the control valve. Have not had problems since. That has been 10 years ago, I blow the box out every fall before I start the furnace.

Thanks so much for your response, I did finally resolve the issue, I believe it was a combination of the thermostat, exposed wire and the thermopile pilot generator. I believe the key problem was the millivolt thermostat. I did a thorough cleaning of the box and burners and it has been keeping me very warm I know they are not the most efficient furnaces, but I prefer the heat they produce. Thanks again.

Hi Dmakaka... I have a similar issue, and have a Western Gravity 4G-75 model. I cannot get the new thermostat to work with the unit. By any chance, would you have a manual, or share with me what you did to get yours working? Also, where did you find the new thermopile generator?
Thank you