Gas furnace blowing cold air?

[bfunk13]

I woke this morning to our furnace blowing cold air.
We burn the stove for most of our heat, but in the early morning the furnace kicks on a few times on cold mornings.
Here is the problem, the furnace is in the attic and i am a BIG boy. I don't think i can get up there and work.
It is only 4 years old and like i said only gets used a few hours a day in the winter.
Thermostat or thermocouple bad? I am no expert but, from what i know the fan should not turn on until the thermocouple says it's up to temp.
Any suggestions on what to look for? What and how to test? I may be paranoid, but i don't trust many service guys to do the right thing for the right price and
i don't know any HVAC guys here.

Thanks for any help!

 

[Duetech]

Any storms/power outages/surges lately? Is your T stat a battery operated unit? My boiler T stat goes bonkers when the batteries get low and plays all sorts of games with my furnace blower. Also my relay for the boiler side (water/air heat exchanger) sometimes get stuck and a slight tunk will free it up so it could just be the relay in your furnace that is acting up and not shutting off when the T stat opens the circuit.

 

[smokinj]

+1 if thats not it is on to the pilot light/igniter switch.

 

[bfunk13]

No storms or outages, it is battery powered and i will try that first.
This was almost a deal breaker when we bought this house, the furnace in the attic.
Thanks for the replies.

 

[laynes69]

Last time we had that problem, it was a bad snap disc. It was sticking after running a cycle where the blower wouldn't kick off. A couple light taps and it stopped so it was replaced.

 

[smokinj]

No storms or outages, it is battery powered and i will try that first.
This was almost a deal breaker when we bought this house, the furnace in the attic.
Thanks for the replies.

Thats where mine is. My igniter went out last year but we really dont use it much. Wood furance and gas firepalce is enough until 0 degrees with 40mph winds. Then you find out the hard way!

 

[bfunk13]

I called the local HVAC guy and he replaced the fan limit switch.
$133.50 parts and labor. I am cool with it, i have no business messing with it, especially in the attic.
Also inspected the unit.
I know most of this was labor.

 

[smokinj]

I called the local HVAC guy and he replaced the fan limit switch.
$133.50 parts and labor. I am cool with it, i have no business messing with it, especially in the attic.
Also inspected the unit.
I know most of this was labor.

I with you on that one. If I didnt install my wood furnace myself I would be lost. (If The simple stuff check good)

 

[laynes69]

It's always good to have things fixed. We have a simple snap disc, while some use a limit control. A gas furnace is pretty simple. I haven't fired ours yet this year. Something I usually do to check things out. I havent cleaned our yet this year either. It's 25 years old with maybe 5 years total running. At 90% efficient I won't be replacing it anytime soon.