Every time the furnace fires up, it blows out the pilot light. Sometimes it will run a full cycle and blow out when it shuts down, and sometimes it will blow out about a minute into the cycle.

We had a tech at the house yesterday for a different furnace issue, and unfortunately, nobody was home when he came. From what we can tell, he changed some of the copper lines going into the furnace and he did remove the air filters.

When we got home the furnace was running fine, but after a couple of cycles it started acting up. We relight the pilot with no problem, but as I said as soon as it starts running, it blows the pilot out.

Could the lack of air filters be the problem, or do I need to call the tech back to the house?

  • 1
    So this started after the guy worked on your furnace? Dec 19, 2012 at 15:39
  • Yes. We had a mix up with the people that filled the propane tank, and had a repair man out for that issue, which turned out to be that the valve on the propane tank was shut off. Opps lol
    – Jessica
    Dec 19, 2012 at 15:49

3 Answers 3


The pilot light worked fine before a tech came out.

The tech left with your furnace in an incorrect state - namely - he removed the filters.

Furnaces are supposed to have filters. That alone is enough reason to call him back.

Call him up, say, 'You left w/o replacing the filters and now the pilot lite is going out. Get back here please, and fix it.'

  • 1
    Agreed, tech needs to make it right. I'm curious to why the pilot goes out though. The filters for circulating air are completely separate from the combustion chamber and should not effect the pilot in any way. Any other theories, anyone?
    – bcworkz
    Dec 19, 2012 at 20:37
  • restriction of gas flow causing the pilot to go out when the main burner takes all the gas??
    – UNECS
    Dec 20, 2012 at 0:40
  • I can't really visualize the physical arrangement, but I'm imagining that maybe - with the filters not in place - there's a strong draft blowing past the pilot, and that the filters normally redirect that draft?
    – MT_Head
    Jan 23, 2013 at 7:25
  • 2
    The house air and the air used in combustion are separate (breathing combusted air would be bad), so the filter shouldn't affect the pilot light. My point is - tech came out, pilot light stopped working and machine was left incorrect (w/o filters) so hold them accountable. Jan 23, 2013 at 11:43
  • @TheEvilGreebo I agree that the filter shouldn't effect the pilot. But as for keeping house and combustion air separate, go ahead and cringe at these bad boys: ehow.com/how-does_5030166_ventless-gas-heaters-work.html And yes, they are still sold in the USA. Apr 22, 2013 at 18:38

I had a tech come by to fix a "won't stay on pilot light."

He had a turkey baster style air blower, and simply blew the dust out of the tip.

Can you try that with a can of compressed air or similar?


A cracked heat exchanger comes to mind first, leaking supply ducts causing negative pressure, a bad thermocouple, bad

  • 1
    Incomplete. Does not explain what the terms mean. Jul 23, 2014 at 14:06

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