Originally Posted by kok328
High limit switch is a device to shut down the system in the event of an over-heating condition in the combustion chamber. There are dozens of types of switches being used. Some are manually resetable and some are not. The resetable types will have a small red button in the center of them between the two wires. Press this button in and try the system again. If it is not the resetable type then you might get lucky by tapping on it to get it to unstick. Otherwise you'll have to replace it. Just be sure to replace it with one of the identical ratin. The spec print on these is microscopic and will require a pair of young eyes or a magnifying glass to see.
Would like to reset/replace my high limit switch but not sure where it is, I do see a sensor on the fire box with two wires, is that it? But no reset switch on it.