gas furnace shuts off?

Question

My wall unit gas furnace comes on just fine, but only comes on for about 2-3 minutes....I'm figuring just when it warms up. At this point, it clicks and shuts off completely, pilot and everything. I've asked people and they tell me it might be the thermocouple, but everything I've found online says that only has to do with the pilot itself. Any help?

It's not like the big wall units...it's basically like a floor unit that's mounted on the wall. I took the cover off and cleaned everything and even scrubbed the thermocouple thing. I looked everywhere and can't find any switches or anything like that.

Answer 1

Any one of many reasons or combination of reasons.
#1)A pilot not impinging on the thermocouple entirely. A visual inspection may reveal a luminous yellow tipped pilot. This is generally caused by lint that has settled in,as air was brought in to help the pilot burn properly, and will result in the pilot flame being pulled away from the t-couple resulting in closure of the appliance gas supply. Take a straw and with your mouth,blow some air into the pilot and at the same time lightly tap on the pilot to tap out lint.
2) There is a very slight possibility that the exhaust vent is restricted resulting in a smothering flame.This would cause the burner flame to smother, and in some systems, a limit or safety switch activation resulting in everything shutting down. This is a major hazard and should be corrected by a heating agency.
3) Although highly unlikely, a pressure problem could exist on the gas company's regulator at the meter. They can check that for you at no charge. As a matter of fact, most gas companies offer free service to appliances, their phone number will be on your bill. That would be the easiest way to solve your problem, have them check it for you.

Answer 2

there has to be something that controls the temperature it will get in the room ....this may be built into gas valve ....if it is bad would cause gas to shut off ,but shouldnt cause pilot to go out also...how do you light the pilot? manually or does the unit light pilot by itself....if manually...it should not blow out unless the flame on pilot is yellow ...should be blue with small yellow tip...if its not blue.this would indicate a gas pressure problem or bad gas valve...if it lights itself then it could have a sensor instead of a thermocouple this would let it light pilot, then burner, then shut off everything if sensor is bad or it detects a problem

Answer 3

It could be the thermocouple, if that's not made then it cuts the gas off. Take some emory cloth and clean it off and then make sure it is in the flame and getting a good signal.

Answer 4

You will need to completely remove the the front cover to expose the entire furnace. towards the top area where the exhaust vent is, you should see a switch. This is a heat limit switch, if the vent is clogged or dirty it can overheat and trip the switch. If the vent is clear and it still goes off, the switch is bad, replace it. Good Luck

Answer 5

The thermo coupling only controls the pilot. The inducer isn't proving the vent switch so it shuts down. If it is overheating make sure you check the heat exchanger to see if it is sooted up. It would be a good idea to have have a CETP cert. tech look at it.

Answer 6

You have a natural gas appliance, have asked a repair question because I'm guessing you have little or no experience repairing it.

I've seen some pretty stupid answers - first off NEVER jump a safety unless you are trained and 100% sure you know what you're jumping. That's simply asking for trouble, and potentially an explosion - yes it happens, and yes I've seen the effects of stupid people doing stupid things.

I have suspicions on what's wrong, and I also suspect that it won't cost you all that much to have a trained and licensed technician repair it.

Natural gas, a little bit of knowledge, and poor advise is a catastrophe waiting to happen. Is your life REALLY worth less than the $100 or so it will cost to fix it?

Answer 7

First of all try cleaning it. Sounds like a furnace is shutting down because its senses its self to be overheating. Some kind of safety device might be defective. Good luck

Answer 8

Your high temperature safty is most likely bad you can jump it out temperarily to see if that is it.