HVAC / Furnace issue... Thoughts?

[Indy_Guy_77]

Well - we turned on the furnace for the first time last night. It'd gotten down to an awesome 64* in the house - and I thought we should bump it up 4-5* before bed then turn it back down for the over-night.

All seemed to go just fine... BUT - the unit (Natural Gas) would seem to work A-OK for 5-10 minutes (and 1 degree) and then shut off. Then it'd come back on - to repeat the process until the desired temp was met.

What could be the matter??

It was installed in December of 2012 (at least I think it was...)

Sure Comfort Downflow furnace model # GF951D075AW48 (95% 2-stage 75k BTU)


Thanks!

 

[GodFearinGunTotin]

My first thought is some sort of over-temp sensor is kicking out your unit. Maybe you got something partially blocking your flue? Do you have CO sensors in your house?

 

[RobbyMaQ]

clean the flame sensor thingy?

 

[Lectric102002]

Paging Churchmouse

 

[BigBoxaJunk]

Does both the burner and the fan go off between cycles? Or just the fan, or just the blower?

 

[Informed Decision]

Bigbox has a good point. Might be the thermostat acting up or a sensor telling it to shut down. By some chance do you recall if all worked well when the air was on?

 

[planedriver]

95% + 2 stage = a furnace guy in my world. I agree with the idea of over temp but every time I have a problem of any time with a furnace it's always a new circuit board. What ever happened to furnaces that worked for 30 years?

 

[red_zr24x4]

Yesterday, mine would run for a minute then shut off. The flame sensor was dirty and the pilot light flame was to small.
Cleaned the sensor and removed a chunk of gunk out of the gas tube for the pilot. Works great now.

 

[Naptown]

Are there diagnostic lights?

 

[ghitch75]

when was your filter changed last?........could be trippin' a high limit because of poor air flow.....

 

[churchmouse]

Flame sensor will not let it run out for but a few seconds or a minute at the most.
Filter could be dirty.
PM me and I will get down there. Sounds like it is hitting one of the high temp limits.

 

[Indy_Guy_77]

Flame sensor...lights...

This is all way out of my realm! It all makes me feel dumb.

It seems upon closer inspection that it's just the blower that's shutting off, though.

 

[churchmouse]

Flame sensor...lights...

This is all way out of my realm! It all makes me feel dumb.

It seems upon closer inspection that it's just the blower that's shutting off, though.

Cycling on the sensor. Might need some love.

 

[Indy_Guy_77]

.

 

[sig-guy]

FYI, your unit is manufactured by Rheem.

 

[Indy_Guy_77]

Think the churchmouse is gonna stop by tomorrow AM and take a gander at the thing.

Glad that I found this out NOW - not in a few weeks where the thing NEEDS to run and may potentially hurt itself by the blower cycling like it does.

Further info: Yes - definitely the blower that keeps going off/on.

There's a "wooshing" sound that comes on first for a few mins... I presume this is a pre-heat stage? After that, I'll then hear an "electric buzz" as the ignition for main heat (??) comes up... Then after a few seconds, the blower will come on and "all will work as normal".

Then the blower will shut off and be back to stage 1. Repeat - ad nauseum.

 

[sig-guy]

"wooshing" as in "sounds like water"?

If so, plugged drain with water in the inducer... Oh forgot its a Rheem, their inducers normally leak...

 

[Indy_Guy_77]

Wooshing was, I presume, just the first stage / mixing before the big burners kicked on. Nothing watery at all.

And the Mouse told me that the burners were hitting their temp limits and then shutting off.

He adjusted things and now all is well.

Strange that those things would be maladjusted after having sat idle basically all spring/summer. Unless somehow the vibration from the A/C caused it.

Big thanks (again) to churchmouse!