I know next to zilch when it comes to my heating and air system, so that's why I'm kind of led to believe this may be something simple. We have natural gas heat for our home. Lately, it's been a little cooler in the day so I've set the thermostat for about 73 degrees and switched the system over from A/C to heat. Now, once I did this, I could hear the system kick on and I thought everything was fine. Our thermostat is right over the exchange vent where we switch out air filters periodically. But... the system kicked off after about 30 seconds and won't come back on. I restarted the thermostat and set the desired temperature again, and it did the same thing. The system isn't staying on long enough to push the heat out to the desired temperature. I went into our utility closet to check the pilot light on our gas water heater, and when I removed the cover, I could see that there was a flame going in there, but I wasn't hearing that distinctive sound whenever the heat is working normally. If I remember correctly, this kind of thing has happened before, but usually after we've lost power to the house from a storm or something. That DID happen about a month or so back, but the power was restored and we've had no reason to turn on the heat since it's been so hot outside anyway. We're still getting hot water for our showers and in the faucets, just no hot air coming through the system. - We are getting heat to our water heater because our showers are unaffected; no loss of hot water.


What could it be?

Am not understanding,, are you worried about the furnace,or the hotwater heater,, in most instances they are two different pieces of equipment, one not having anything to do with the other,, is this not your case?

You could go to the sticky at https://www.askmehelpdesk.com/heating-air-conditioning/noma-thermostat-help-140213.html#post664441 and read up on furnaces. If you then think you better understand where the problem is, you could post back. If not, you may be better off calling a technician. You may have a bad blower relay. Unfortunately, that can mean an expensive circuit board. They aren't that hard to replace, but you need to be very sure that is the problem.

Actually it appears that perhaps our being well overdue in replacing our air filter may have been the culprit. I, and a friend who is knowledgeable in HVAC, went under my house to check out the system and everything there looked fine. After I replaced the air filter, which was filthy, it appeared that it fixed the problem. The last time I had this happen, it ended up being the pilot light being out on our gas water heater, but it definitely wasn't the case this time.

On second thought, we started having the problem again so it really had nothing to do with our air filter. We had someone come out and take a look, and from what he said, it seems that our "impeller" is failing. I know it's not the big air handler out back, it's something that's underneath the house that's not working properly. I'm not familiar with this stuff at all.

Not the impeller but the inducer. The inducer is the motor that pushes the exhaust out to the chimney. Try cleaning the flame sensing rod which is located in front of the far left hand burner. It is a thin rod which will dirty up with time. A piece of steel wool rubbed gently over the surface will do the trick. Also try tightening all of the screws that hold on the inducer housing. If it has come loose it will drop the pressure switch and you will not have heat. Good Luck