You probably want to know what a thermocouple is to begin with! On a gas furnace, it is a part near the pilot light and considered the safety device that will turn off the gas if the pilot light diminishes and turns off or if you have electric, the igniter will fail.
Before you begin any repair, get out your manual for the unit. If you don’t have the manual, you can go to the manufacturer’s website and with the model number (located on the unit), and download. You can also do a little research on the Internet.
First, if the light or the pilot light won’t stay on, more than likely the thermocouple is faulty and either should be adjusted or replaced. Usually you should replace it. Tools you will need will be a wrench and the replacement thermocouple. Make sure before you purchase it if you are doing a self-install, that you have the correct part for your unit. (Common sense but you may just end up with something you put on a space ship instead of your furnace.)
Try doing an adjustment. Tighten the thermocouple with your wrench and don’t apply pressure, just turn to tighten very slightly. Try lighting the pilot and if still goes out, then replace it. Make the call if you will do it yourself or call a professional. Thermocouple replacement may be a bit much for you.
First, locate the copper leader and connect nut inside the threaded portion to the gas line. Then under the thermocouple tube, unscrew the bracket, which you will notice, hold the thing in place. If you get stuck here, just call for help. You want to be safe especially when working with gas.
If things are going well, put the new thermocouple into the bracket hole and make sure that the steel tube is pointing up and the copper lead is pointing down. Now, screw the nut over the tube under the bracket. With a slight push, connect the nut to the copper lead that goes to the copper lead making sure the connection is dry and clean.
Without over tightening, turn the screw nut into place. Make sure what you have installed matches up with the manual or the Internet diagram. If you happen to smell gas, make sure it does not over power you. Turn the gas off until you are finished. Gas is nothing to fool around with.
Originally posted 2011-07-22 12:54:25.