Pilot Light works once, then have to re-light after furnace goes off

aransas42

My pilot light is being extinguished by the furnace, at least that is my opinion from what I am witnessing

The pilot will light easily and stay lit for days.

But, as soon as the furnace comes on, burns for a while , then goes off, the pilot light is gone.

I can reproduce this every time..

I was curious to see if the air conditioner would also extinguish the pilot light, but it did not.

any ideas???

note: i am preparing for the winter not wanting to wait until the last minute. is it possible that the system will act differently once it turns cooler?

This is an old Coleman Presidential II furnace in a mobile home with a Rheem condensor and a-coil in the air handler. There is a Hunter 4-wire thermostat.

rvegab00

Hi.

Furnaces are a pain in the arse...

In know this is a diy forum...but since your dealing with what I would guess is gas ... I'd be very cautious and take into consideration your safety...

I'd recommend you get a hold of a company to service your furance..... its a great thing to have done before winter and even more so if you haven't had the furance serviced in a while....

Hopefully its not anything serious...
goodluck

aransas42

Thanks for the safety advice. seriously!.

I agree, but, I like to do my homework before calling the "experts". I have found it best to interact with service men when you at least seem to know what they are talking about.

So, if I promise to call out a service man, will you give me your opinion(s) of what could cause this?

Doesnt seem like a wiring problem or thermostat.

Doesnt seem like a gas valve problem, or is it?

Doesnt seem like a thermocouple problem.

How about loose duct work? or faulty propane supply or ???

ideeas and discussion please.

Viper16

Is it windy there? could be a draft hood needs to be installed or a damper came undone.

Does the pilot have a strong flame too it? it shouldn't get blown out during light, unless you have too high of gas pressure...this would cause the flame to blow out. Where is the main fuel burner regulator?


EDIT:

I could see if the gas pressure coming in was too low that the main burners would starve the 1/4" pilot burner and cause it to flame out. The regulator or main shut off valve for the system could have a semi-clogged orifice.

rvegab00

oh i have no idea what to do about it, just giving some general safety advice....
gotta be careful with those gas appliances man.

aransas42

Hey Viper16, I think you are on to something.

The pilot light seems strong, blue flame, no flickering, will burn for days until we demand the furnace, then all is well until the furnace cycles off.

We moved since last winter, bought a new propane tank and regulator (at the tank). Maybe they sold us the wrong regulator? Plus, maybe some trash got into the system.

I will have the pressure checked and see if the main burner is starving the pilot, but the furnace flame seems strong.

Maybe as you said, it is too strong.

The pilot seems strong, doesnt go out by itself, and it is windy here.

Thanks for the idea, i was reaching on this one.

Viper16

Also check if it the main burners are weak when it is lit...it could be that the regulator may be set way to low and that you are, as we have stated, starving the pilot.

qbert

You may want to have your furnace inspected a crack in the heat exchanger can cause those symptoms

Viper16

Good Point! and cracks in gas heat exchangers is not uncommon.