# Gas Furnace Burners not Igniting!?



## yuri (Nov 29, 2008)

Post the make and model # and pics of the burner area. Many different systems out there. Check for 24 volts AC across the 2 wires on the gas valve when the HSI is glowing. If no 24v then the circuit board is not energizing it.


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## SD515 (Aug 17, 2008)

A roll-out switch may have tripped keeping the 24v from geting to the gas valve.


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## hvac benny (Dec 29, 2009)

I hate to state the obvious, but is your gas on? Both at the appliance and at the meter? I've seen this countless times, so just thought I'd throw it out there.


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## beenthere (Oct 11, 2008)

IS the gas valve turned on?


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## drupason (Oct 16, 2010)

yes gas is turned on..it was working a week ago.. I will check the volts when I get home, thanks for the tips


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## yuri (Nov 29, 2008)

Check the meter shutoff outside. I once had a vandal shut one off as a prank?


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## hvac benny (Dec 29, 2009)

yuri said:


> Check the meter shutoff outside. I once had a vandal shut one off as a prank?


I was once told by another tech that he shut off the meter at a Wendy's because they were rude to him. I wouldn't advise anyone to do the same.


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## kenmac (Feb 26, 2009)

Years ago. A guy got mad at his neighbor. Called the gas co. & told them he lived there & to disconnect the gas service to his home. They called me because they had no heat


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## beenthere (Oct 11, 2008)

drupason said:


> yes gas is turned on..it was working a week ago.. I will check the volts when I get home, thanks for the tips


That was last week. 

The gas company could have been working in your area, and turned off your meter to work on the main. And if no one is home when the open the main up again. they won't turn your meter back on.

At least here they won't.


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## drupason (Oct 16, 2010)

SD515 said:


> A roll-out switch may have tripped keeping the 24v from geting to the gas valve.


It was a roll out switch! Thanks so much


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## beenthere (Oct 11, 2008)

So are the flames rolling out?


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## yuri (Nov 29, 2008)

They are a critical safety device and SHOULD NOT trip for no reason. May have a downdraft situation or overfiring burner or other problem. Recommend you get a Pro to check it out.


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## hvac benny (Dec 29, 2009)

kenmac said:


> Years ago. A guy got mad at his neighbor. Called the gas co. & told them he lived there & to disconnect the gas service to his home. They called me because they had no heat


I wonder who had to eat that one. I now work for the gas utility, so I know that running a service costs a minimum of $1500, and when we terminate a service that we also remove the service line from just after the service tee. So, removing a service, then re-establishing a service would definitely cost a few beaver pelts, or whatever it is that you yanks use for currency exchange :laughing:.


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## drupason (Oct 16, 2010)

so what are the most common things that cause the roll out switch to disengage??


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## beenthere (Oct 11, 2008)

Blocked flue, or chimney. Bad heat exchanger. An exhaust fan somewhere else in the house pulling the flame out.


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## yuri (Nov 29, 2008)

Gas valve regulator failing and supplying too much gas. The infamous notsmart valve has that problem along with others.


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## j66996 (Sep 4, 2010)

So, if you have the 24V across the gas valve and still no gas is the valve probably bad? Do they go bad ?


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## yuri (Nov 29, 2008)

Yes..


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## j66996 (Sep 4, 2010)

Thank you!


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## drupason (Oct 16, 2010)

well the flue is all clear what should I check next?


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## SD515 (Aug 17, 2008)

Which sensor tripped? Where is it located?


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## beenthere (Oct 11, 2008)

Any exhaust fans in the house?

Could have a crack in the heat exchanger.


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## drupason (Oct 16, 2010)

well had a pro come check it out.. apparently the heat exchanger is cracked :furious:


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