No gas to the suburban furnace

[N147JK]

Maybe the thermostat side of the circuit is faulty. I hooked up the power and thermostat wiring to the furnace, but left the gas line disconnected. Then I turned the thermostat up and checked that the start-up cycle was operating correctly - the fan should come on, then shortly after that confirm the valves have opened.

[Clarkboulder]

Yeah all that happens. Thermostat operates as expected. Thanks

[Clarkboulder]

I think I’m hopeful that if I give it one more try and if i hook everything back up it may just work again. Tested the module and the lights are doing the right thing. The dinosaur aftermarket module board is different that the OEM and so it’s a steady green light and then a red light when the electrode fires then back to green until it cycles again for another try.
I’m hearing a very audible solenoid click now so maybe all the testing freed something up. 🤞

[simplesez]

Fingers crossed!

[N147JK]

OK good.. remember it can take several startup cycles before enough gas is present at the furnace to get it to run. I think it tries 3 light-offs during each cycle, then shuts down. So if it doesn't light, keep trying - at least 4 or 5 full cycles if necessary.

[arctictraveller]

Originally Posted by N147JK

OK good.. remember it can take several startup cycles before enough gas is present at the furnace to get it to run. I think it tries 3 light-offs during each cycle, then shuts down. So if it doesn't light, keep trying - at least 4 or 5 full cycles if necessary.

That's correct and normally thats caused by air in the hose. Purging the line by cracking the fitting usually eliminates that problem and results in a quick start.

[Clarkboulder]

Yeah. The furnace fired up upon reinstalling. Thanks all for your help and advice. I got away with only $7 burner gasket. …or did I? …..
I notice that the flame is very strong but above the blue is tall yellow flame. I don’t think that should be like that. The furnace is reaching 480F surface temp on the burner chamber which is hotter than I expected for such a confined space but it’s exactly back where it was installed previously so I guess it handles that. Since I inspected and cleaned the relatively clean burner and chamber while out should I suspect that my regulator might be bad causing this yellow flame �� issue? I also get it on one of two stove burners and have all summer. Is this an emergency (she’s gonna blow) fix or something I can leave until the tank empties? Easy or pro job?

[N147JK]

Originally Posted by Clarkboulder

I notice that the flame is very strong but above the blue is tall yellow flame

Same thing happened to me. It would run 2 or 3 minutes then start to flare-up as you describe. Had me worried. I figured there was probably air in the line that had to work its way through. After a few hours of operation the problem disappeared. The furnace runs very stable and like new now. Just wanted to relay my experience.

Remember there is that limit switch in there that will shut it down if it over-temps (assuming it is working properly). I replaced that switch as part of my "tune-up" - it's inexpensive.

[Clarkboulder]

Originally Posted by N147JK

Same thing happened to me. It would run 2 or 3 minutes then start to flare-up as you describe. Had me worried. I figured there was probably air in the line that had to work its way through. After a few hours of operation the problem disappeared. The furnace runs very stable and like new now. Just wanted to relay my experience.

Remember there is that limit switch in there that will shut it down if it over-temps (assuming it is working properly). I replaced that switch as part of my "tune-up" - it's inexpensive.

Thanks. That’s helpful info. I tested the continuity of the limit and seems good. Who knows.
My flame does not flare inconsistently. It looks that way from start to off. But I’ll run it a few times and see what happens. I’m hopeful. I think I might have the regulator assessed by someone since this flare also happens with one of two stove burners. No soot seems to be present anywhere. The burner was pretty clean inside.

[racer_rr]

Change the regulator. My old furnace started be difficult to light when cold or +8000ft. I replaced (maybe with a higher elevation version....don't remember) and all was well. Old reg was full of black hydrocarbon gunk.