Gas Furnace

[riverkabin]

When the furnace ignites, the pilot light is forcefully blown out by the combustion.

[SeattlePioneer]

Are you getting a loud "boom" when the burners light off? That's called delayed ignition.

The more common reason for what your describe is a pilot burner and pilot orifice that need cleaning, and are susceptible to being blown out like a candle.

So does the burner light normally, or with an abnormal amount of noise?

[riverkabin]

Originally Posted by SeattlePioneer

Are you getting a loud "boom" when the burners light off? That's called delayed ignition.

The more common reason for what your describe is a pilot burner and pilot orifice that need cleaning, and are susceptible to being blown out like a candle.

So does the burner light normally, or with an abnormal amount of noise?

The pilot is strong. It takes 30 seconds and when the gas ignites its like a flame thrower. On problem is the furnace is under the house. I go up, turn the thermostat up and 30 seconds later froom the gas ignites. I go under to the furnace and the pilot is out. I can blow on the pilot and it won't go out.

[SeattlePioneer]

All right --- you are describing a delayed ignition condition.


The usual cause for that is burners that need cleaning --- sometimes they are rusted out and need to be replace.

You need to remove the burners and clean them with a wire brush, taking particular care to make sure that the crossover ports that allow the flames to carry over from burner to burner are clean.

If I were doing this job I'd observe the delayed ignition problem by observing the burners light or fail to light by operating the electric gas valve manual control to turn on the gas and observe the partial ignition, shutting off the gas again before the burners light off.

But that's probably not a good thing for you to try, especially since you'd probably have to do it multiple times before you saw where the flame was failing to burn properly.

So best to just clean the burners and inspect them for rusted out and enlarged burner ports.

[riverkabin]

Thank you very much. I had an idea this is what the problem was.

[ecman51`]

I'm not sure, but I gather this from one of your posts - that if you have an issue of being alone without a helper, and you turn up a stat, and the time you make your way all the way to the furnace, and you can't observe the sequence because by then it already happened and is over with and is too late -

- then first turn off the furnace at the furnace (hopefully it has a switch on it) and then turn up the thermsotat, then go back down there and while you watch, turn on the furnace switch. If no furnace switch, use the blower door as the furnace switch. First leave the door ajar, then when you return to the furnace ready to observe, put the blower door back on, and the door's safety switch will allow the furnace to start up.