Is my thermocouple going out on my furnace?

Good morning,

If you have a gas furnace, there are a number of safety devices within the unit to ensure proper operation. At the center of these devices is a control module that essentially takes data from a number of points, and provides the signalling to start the various systems within the furnace (purge blower, ignitor, gas valve, blower fan). The thermocouple is one of the safety devices. After initial ignition, the thermocouple heats up and produces a small voltage that indicates to the control module that the furnace is firing (as opposed the gas valve opening and having no flame produced). If, after a very short period of time, the thermocouple does not produce this small voltage (about 30 millivolts - 30/1000 of a volt), the control module's logic circuitry shuts the gas valve. If the thermocouple is defective, it will behave as if there is no flame. Often, the blower fan will continue to run for a minute or more, resulting in the cold (unheated) air that you feel. Please be aware, however, that there are other safety devices as well, including a pressure switch (connected with a soft rubber tube). When the furnace initially starts, a purge fan clears the combustion chamber of any stray gas and provides pressure to the vent or chimney for the draft necessary to support good combustion. The pressure switch basically senses that draft and signals the control module that it is OK to go ahead and continue the start-up (turn gas on and ignite). Finally, there are usually a series of "overtemperature sensors" that appear as flat disks mounted strategially around (but outside) the combustion area. Each will have two wires and they are connected in series. Essentially thermal fuses, if the fire comes out of the combustion chamber and the other areas of the furnace get too hot, these "fuses" will open and shut the furnace operation.

I am having problems with my furnace and was looking for help as well. I hope that this information helps in getting you some heat!

(good luck with the idiot landlord as well!)

Regards,

Len in Virginia

try the combustion blower or ignitor on the furnace. mine went out and did the same as yours, it's easy to fix, depending on what kind of furnace you have.

Just day, 'Furnace no heat,Gas make me dead, you fix ok!'