[Rrambaud]

Help! It's cold! My 3-year old Goodman GMNTE furnace cycles perfectly, but it will not light on it's own. If I blow a small puff of air toward the manifold/HSI/ heat exchanger area as soon as the HSI is glowing and I hear the gas valve click open, then it fires right up every time.

After igniting, all 4 flames look fine and the furnace heats up to the set temperature and shuts off. Then, it will cycle forever without lighting, giving me the "ignition failure" code until I go puff into the sight glass hole or remove the cover and puff directly into the manifold area. (We are talking about one partial mouthful of air, not a lungful)

It seems to me that the gas valve, HSI, flame and other sensors, gas flow etc. must all be OK or it wouldn't light at all. Also, it doesn't seem as though the flames would look good and steady if there was something wrong with the air or gas supplies, airflow/filter, exhaust vent, etc. Could it be that the HSI unit is worn, and does not glow quite hot enough to ignite the gas stream without help, or something like that? THis is sooo weird...

THank you very much to anyone who can help shed some light (heat) on this!

[therinnaiguy]

Sounds like a gas pressure problem. Did this just start happening as the temperature got colder or has it been doing this right along?

[NorthernHeat]

Clean the burners good.

[Rrambaud]

First, thanks very much for your help, Therinnaiguy.

This has been our coldest stretch of weather so far this year, and this is the first time that I have seen the problem. It is supposed to be 20 degrees warmer tomorrow, if that matters.

A couple of times this morning, I saw that the furnace kicked on and seemed to think it was firing, because the blower was blowing cold air. I don't want to confuse things, but thought I should mention this in case it indicates some kind of sensor problem.

Meanwhile, I can keep the house warm by turning the furnace breaker off and on to reset things, and then blowing into the sight hole when the HSI glows and the gas valve clicks. This works every time!

Are you suspecting that the gas line somehow freezes, or that more gas consumption by my neighbors is reducing the available pressure. Or, does the pressure drop when it gets cold? If so, am I at the mercy of the pressure being supplied by the gas company, or is the output pressure adjustable, or do you have any other advice?

[therinnaiguy]

It would be a good idea to let your gas company know this is happening. Also, if when temperatures get warmer and the problem goes away, I suspect a bad gas regulator at the gas meter. It is not uncommon.

[Rrambaud]

Thank you, Northernheat.

I am an engineer and generally well-versed in technical stuff, but not an HVAC guy. I know my limitations and take safety seriously. I would like to try cleaning the burners, as you suggested, and will shut off the gas and electric to the unit first.

Could you please be more specific about cleaning the burners? The heat exchangers and the manifold pipes and such seem very clean already. Do you mean the actual gas nozzles? I will also search your previous answers to see if you've already told someone how to do this and again, thanks for the help.

[NorthernHeat]

The burners are between the orifices and the heat exchanger, they sort of look like this at the end =0=. The zero is the main burner opening and the = is what's called the crossover, or flame extenders. It is these small slots on the side of the main opening that could have a spider or rust in it preventing the gas from reaching the ignitor or extending the flame down the entire row of burners. Also be sure the ignitor is placed well and hasn't been bent or moved out of position.

[Rrambaud]

OK, lots of good advice. This is my first try at Ask Me but I am impressed. I appreciate your help very much.

I will contact the gas company and find out about the pressure, and I will clean the burners as you suggest, NorthernHeat. I will post my progress.

Thanks again!