Hi folks,
The problemn Ihave is that my heat will not come on by itslef with any regularity. I frequently wake up to a 60 degree house. If I turn the thermostast to off and then back on, the furnace kicks in and starts running. Does this sound like a pure thermostast problem, or furnace issue. The thermostat is a basic honywell model, not dual zone or anything like that... on/off/auto cool/off/heat . Thermostat is about 5 years old, and thisis the first year it has done this. Help! Thanks in advance,
Dutch

Sounds like a furnace problem and all you are doing by turning the thermost on and off is reseting the circuit in the furnace.

Model number of furnace?
Brand name of furnace ?

Thanks - and you may be right. It is a Carrier - Weathermaker SX... thats the only nomenclature I can find.

Have you ever turned the thermostat down until you hear a click and then back up until you hear the click. What this should do is act as though the heat has turned the thermostat off and then it has cooled and is then calling for heat again. What I would like to know is what happens at the furnace when you do this. First you should hear the inducer motor come on for thirty seconds or so, now the hot surface ignitor should start to glow, after fifteen seconds or so the gas valve should open and ignite, they should heat for thirty seconds or so and the main blower should run until the thermostat is satisfied.

Now if you got to the point where the hot surface ignitor lights the burners but does not stay on but a few seconds or less, and then it repeats the cycle until it shuts itself off and locks out for sometime up to three hours. If this is the case you probably have a bad or dirty flame sensor.

Let me know if this is the way it is acting and I will give you a possible solution.

Thanks for the response letmetellu -
I have never tried that. I have moved the thermostat up and down in temp an tried to kick it on that way... with no luck. Seem to have to turn it off and on to make it work. Last night I found that by putting it on 74 degrees, the heat stayed on all night. Very hot and expensive house... but warm none-the-less. I should also add, this furnace is abouit 20 years old... I am selling the house in two years and would rather not put a new one in right now. To add insult to injury (as a side note), my gas hot water heater (10 years old) went out yesterday as well... cold shower this morning!!
Thanks again!

((Last night I found that by putting it on 74 degrees, the heat stayed on all night.))

If the unit ran all night with no problem and the thermostat was left alone it points to a possible thermostat problem. At first I thought it might be the furnace but with this new information I would look in to the thermostat.

Now I assume the furnace cycled on and off with the thermostat last night and just not stayed on all the time?

If you can try to jump R and W together on the thermostat. This will directly connect the heat circuit and bypass the thermostat for continuous operation. You can also do this at the furnace connection for the thermostat.

You will have to use the disconnect switch on the side of the furnace to turn off or on.
This is just a simple thermostat bypass test to see if the furnace will keep running as it did last night. You can cycle it on and off to make sure the furnace goes off and on as much as you want until you are satisfied that the furnace is OK and the thermostat is the problem.

To Bad you do not have a cheap thermostat laying around because you could hook it up temporary just to see how the furnace cycles.

Since you furnace is somewhere around 20 years old I may have given you some invalid information because it is possible that you furnace is not equipped with the parts that I was telling you that might not be operating right. You might do what HVAC said and see if you can come up with an answer. Good Luck