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VinceA 10-30-2010 10:19 AM

Heater not staying on

I just bought a new Honeywell programmable thermostat at the beginning of the summer, and it worked fine throughout the summer for my air. Now that the winter is here, I'm running in to some problems.

I had my stat set to 67 last night. When I woke up this morning, it was 57 degrees in here and the heater was not on. When I turn the switch to off, and turn it back to heat, the heater clicks on right away but it will not stay on. The thermostat has the "Heat On" displayed on it, but he heater is not running. This leads me to believe it is most likely a problem with the heater and not the thermostat. I just want to get a few opinions here, but I imagine it is a problem that I need to call someone for. I double checked the thermostat and it is hooked up correctly.

yuri 10-30-2010 10:36 AM

Post the make and model # of furnace and pics of it with both doors off. Does it have a error code light viewing window.

VinceA 10-30-2010 10:46 AM

I'm not sure about the error code window, I can get pics and the model # later this evening, I'm heading out now. I only know of the door in the front, what would be the 2nd?

yuri 10-30-2010 10:57 AM

Some only have 1 door and others have doors behind that one. Remove it and see.

VinceA 10-30-2010 09:15 PM

4 Attachment(s)
Alright here are a few pics attached. I can get you closer anywhere if you need. Thanks.

kenmac 10-30-2010 09:27 PM

Look on the circuit board. To the left toward the top there is a small red light( light is off now). On a call for heat push in the button sticking out of the small box on your left & watch the light. If it blinks count the blinks. Look on the back of the blower panel for the code

VinceA 10-31-2010 10:55 AM

Alright, went ahead and did that and the light stays on, which says everything is fine.

Does this sound like its an issue with the thermostat? The part that boggles my mind is that the heater goes off when the thermostat still has the "Heat On" icon on the screen. I double checked the connections and everything is connected correctly. I called a heating company and he said it sounds like the thermostat but they obviously wont know until they come look at it, so I have him scheduled to come out tomorrow. Part of me wants to just go buy a new thermostat and put it in and see if it fixes it before he comes out, if it doesn't I can always return it.

yuri 10-31-2010 11:02 AM

Check between W and C on the board with the door switch closed and calling for heat. Should have a steady 24 volts AC. If not it is the tstat.

VinceA 11-01-2010 12:34 PM

I had a hvac buddy of mine run me through some stuff on the phone. We bypassed the thermostat and it still had the same problem. The blower always stays on, and the flame's kick on for about 5 minutes, then turn off and the status light blinks 4 times, which indicates an open limit switch. It stays off for about 30 seconds and kicks back on for about 5 minutes and keeps repeating this process. I have a heating company coming out tomorrow evening. Is the switch something that I can replace myself?

kenmac 11-01-2010 01:05 PM

It must be cycling on the high limit.. Not moving enough air across the heat exchanger or cracked heat exchanger.. Check air filter. if you replace the limit without locating the problem. You will get the same results with a new limit

VinceA 11-01-2010 01:11 PM

It does the same thing with the air filter out

kenmac 11-01-2010 01:16 PM


Originally Posted by VinceA (Post 526703)
It does the same thing with the air filter out

Dirty coil ,blocked off vents,etc, OR Cracked Heat Exchanger

VinceA 11-01-2010 01:22 PM

I checked all the vents, every one in my house is open, and there is a good amount of air coming out everywhere. I'll just let them come out tomorrow and find the problem. Atleast I know a good amount to be able to tell him now. Do you expect me to be looking at a large repair bill?

kenmac 11-01-2010 01:26 PM

If it's cracked heat Exchanger... Yes. If they can still be had for your furnace. If heat Exchanger is cracked...I would opt for new furnace

VinceA 11-01-2010 01:30 PM

How would you know if its cracked? The furnace runs fine except for the flames keep cycling. Obviously that open limit switch is telling it that it is getting too hot, but is the only way to tell by taking it out and looking at it?

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