furnace burner???

[chrisevansac]

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had this one last night. inlet pressure is 6.9 and outlet pressure is 3.45. i cleaned the burners but the only one dirty was the first one that is rolling back at start up. cleaned orifices. still has roll back at start up. i did notice when i was turning the furnace on and off to check it, that if i didnt let the inducer completely stop before turning it back on it wouldnt have roll out. what do yall think?

[rchristie420]

did you inspect the heat exchanger?

[Snapperhead]

did you clean the pilot orafice ?

its like the gas valve is opening too slow

can you swap burners around ??

[toocoolforschool]

check the amp draw on inducer fan motor.

[chrisevansac]

Amp draw was .9 name plate 1.7

[GastecD]

That is strange, make sure to share the outcome. Never know when youll come across something like this

[chrisevansac]

I do remember the valve took about 2 or 3seconds to get to 3.45. Is that normal or is it usually immediate

[Snapperhead]

I believe I heard they do make valves that are slow openers , i dont know enough about them to tell you anything , but if one got installed into that furnace on accident , it will act similar to what you are seeing

If the pilot flame is Not big enough it could do that , or make a Whoosh sound

Some are a real pain to diagnose

[gravity]

Delayed ignition. Check the runners on the burners. Make sure they are spaced enough. Was the valve replaced?

[gravity]

Let the furnace run for 5 minutes. Turn off gas valve, let flame go out, turn it right back on and see if it lights normal

[Snapperhead]

Let the furnace run for 5 minutes. Turn off gas valve, let flame go out, turn it right back on and see if it lights normal

ahh .... you are bypassing the valve this way , checking to see if valve is opening too slow , good idea !

[chrisevansac]

valve was not replaced. it was original

[chrisevansac]

it will light normal because the inducer i still running. it lights normal when i cut the switch off and back on before the inducer has time to completely stop.

[gravity]

pull the flue pipe off and try it from a dead stop and then while its running. check the runners and make sure they are clean.

check the manifold. there could be lots of spiderwebs in it.

[James Colver]

Sounds like a cracked heat exchanger.