Hello hvac specialists. I live in Alaska and have a hanging Modine gas heater in my garage. It got down below -10 this week and my heater's pilot light won't stay lit. It is a Model PA30AB Modine heater (and yes, I think it is old - possibly even 20 years or more, but I just bought the house).
At first, I got the pilot light to light a couple times, and the burners to kick on for a while, but then after running for a few minutes the flames would go out again.
Now, I cannot even get the pilot light to stay on (regardless of how long I hold it, it always goes out as soon as I try to turn the switch to the "on" position).
What might the problem be? How can I trouble shoot this?

 

The likely problems in order of probability are---

dirty pilot light

defective thermocouple

defective gas valve.

How long has it been since this equipment was serviced by a competent person?

Descripe the appearance of the pilot light when lit. Is the flame blue or yellow or yellow tipped? Is the flame sharp like a blotorch, or soft and lazy?

 

I do not know the last time it was serviced. I tried to brush any debris off the outside of the pilot light, but it did not really help. The flame is sort of lazy - much like an lighter would produce and mostly blue but sometimes has a small yellow / orange tip. It is usually blue, but not nearly as strong as a torch flame.

 

I'd start by disconnecting, dissassembling and cleaning the pilot burner, including the pilot orifice.

The correct procedure would also be to measure the power output of the thermocouple and the voltage at which the gas valve drops out, but you probably don't have the fitting needed to do that.

Absent that, replacing the thermocouple would be the next thing to do if cleaning the pilot burner doesn't solve the problem.

If that doesn't work, replacing the gas valve would be next.

 

Thanks - I will try that tonight. I appreciate your input.