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+-- Thread: Furnace Issue (/showthread.php?tid=7346683)
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Furnace Issue - Andydiy - 02-26-2019
I put in a new Tempstar high efficiency two stage natgas furnace about 3 years ago. This entire heating season and part of the last heating season I have noticed an issue when there is a call for heating the fan will start in high speed, the furnace will fire run for a few seconds, shut off, then on the second start it will run fine.
I can't say for sure but I think it does this every single time it fires. I replaced the flame sensor with no change in behavior.
The only other issue I have had since i put this furnace in is the intake acted like it was clogged so I changed out the 2.5" pipe and went to a 3" intake and also did a more direct path to the outside. The odd thing was when I took out the 2.5" line I didn't see a clog but it did fix the problem. I also have changed the filter pretty regularly. Also, it looks like the ignitor is working.
There is no trouble code that I can see but I have never looked at it while the issue is happening.
Any ideas...? it looks like the igniter is working fine as well.
RE: Furnace Issue - blackhat - 02-26-2019
Is this a 40" high cabinet or the new shorter cabinet?
RE: Furnace Issue - Duane N - 02-26-2019
What proves the combustion blower is running. I know on standard efficiency furnaces they use a pressure switch connected to the inducer motor housing and some trash would get in the tube between the housing and the pressure switch.
RE: Furnace Issue - Snipe Hunter - 02-26-2019
I inspected a home recently with the same/similar issue. The fan would kick on, the flames would light and then it would shut down. Then the fan would come back on and the flames would ignite and all was well. It was also a very noisy unit. This was a Goodman unit, they're generally a little noisy but I could hear it throughout the three story house.
RE: Furnace Issue - daddo - 02-26-2019
Must be throwing a code. A good start.
RE: Furnace Issue - blackhat - 02-26-2019
Is it connected to a 2 stage t'stat or a single stage? Is there a jumper between W1 and W2 on the furnace board? Are the dip switches on the board configured for the type of t'stat? Are the pressure switch hoses and drain hoses properly configured for the orientation of the furnace? Is the furnace sitting level and plumb?
RE: Furnace Issue - daddo - 02-27-2019
Indoor blower running first is sometimes a limit opened or the draft psi switch. They are sometimes wired in series.
RE: Furnace Issue - blackhat - 02-27-2019
At this point we don't know if it's the draft inducer fan or the main blower he was referring to.
RE: Furnace Issue - Duane N - 02-27-2019
(02-27-2019, 01:20 AM)blackhat Wrote: At this point we don't know if it's the draft inducer fan or the main blower he was referring to.
I kind of agree and after re-reading it I'm wondering if there's a purge cycle for the inducer motor. I know on some older commercial Trane roof top units (Voyagers) on a call for the heat the inducer motor would start out on high speed as a purge cycle, energize the glow coil then the inducer would run in low speed and ignite the burners.
RE: Furnace Issue - Andydiy - 03-01-2019
Sorry, I abandoned my own thread.
The blower motor is what turns on as well as the burners.I know this because I can hear it and feal it at the register, I can also hear the burner kick in as well with the fan.
I will check switches on the main board. As far as the thermostat goes I believe I just checked that at the start of the season and it was wired correctly. I had read that if it was set for the wrong kind of furnace fuel it could be a problem.
The furnace is about 40" tall.