Furnace not staying on

[Deek]

Hello,

I know it is requested that I include a Make & Model of the furnace, but I don't have that handy at the moment as I am not at home. I may be able to update that information later. From previous research, I believe it is no longer made.

The problem:
The furnace won't stay on. The pilot light will remain lit. I can get the furnace to kick on when hitting a red reset button. More often than not, I normally hear a click about 5 minutes later. Upon checking the furnace, I can see that the furnace has kicked off (pilot remains lit).

Now, I've done some cleaning of the vents, tried different temperature settings on the thermostat. I have even turned the gas off, hit the reset button, turned the knob to pilot mode & relit the pilot & turned it on.

Sometimes, it will work and kick on & off on its own (Yet this is rare). I'm from the Upper Midwest, so we are currently getting some cold nights, but the days end up making it pretty warm inside. So I've turned down the thermostat prior to leaving for work on nights I did get it to work.. But than, normally, the following day when I get home from work I may turn it up and it'll kick on like normal but later stop working like previously... (Can't remain on..)

My question is: What are some methods to fix or find the problem?
I think I've researched this before, and it has mentioned that a thermocoupler would need replacement.. They can sometimes be cleaned and will help. But, since I believe they no longer make my type of furnace, would finding replacement parts be extremely difficult?

Any help, would greatly be appreciated. Also, I'll try & get a Make & Model later today as I am hoping to fix this issue.

Thanks,
Deek

[Deek]

Make: Duo-Therm
Model: 78001-001

Hope that helps...

[Mark]

Hi,

If the pilot stays lit, your thermocouple is fine. When the burner shuts off, does the blower shut off at exactly the same time too? If it does I'd say a limit switch is faulty. If the blower shuts off a few seconds later, then it's possibly a faulty fan switch.

This is your limit switch: http://www.aberdeenhomerepair.com/store ... tch-3-3797
This is your fan switch: http://www.aberdeenhomerepair.com/store ... ailable%29

Mark

[Deek]

Thanks for replying.

The blower motor actually stays on for quite some time. So I know it doesn't shut off right away. I am hitting the reset button a lot, because after a period of time it works for awhile. It's still early in the year where I need to turn it down during the day because it'll get pretty warm inside if I don't.

From my research that I have done, it would appear that it would be the flame sensor. But, looking online I can't seem to find a possible replacement. Is the sensor line likely meant to be flexible?

If needed, I can upload pictures of the unit. Basically the pilot assembly from within the furnace ad the outside unit.

The only line that directly sits in the flame is what I was assuming is the flame sensor. From what I gather, the line is flexible to an extent, considering how it is ran. It seems to be a thicker copper like wire...

Maybe that can help narrow it down. Flame sensors appear cheap, so it would be a great place to start on a trial/error fix.