Hi limit switch

Hey Mr. Wizard,

A few weeks ago my burner stuck on and blew a hose. found trash in the flow switch was the problem. works fine now. But shouldn't the high limit switch have cut out power to the burner before the hose melted? How can I test the switch?

Thanks John,
Adrian

It depends on the High limit the switch is set for. Some of them are set for 350degF While others are set for 210degF. If the wire to the switch is shorted or melted together somewhere it will not shut the burner off. Check the wire from it's starting point to the electrical box. The most common falt can be found there. The wire will touch a hot spot on the burners outer shell and melt the wires together. If the highlimit switch is bad the burner usually won't work. That thing is just a thermostat set at a preset temp. You can test it with a ohm meter or a light bulb and a power source. Just hook it up in series as if it were a light switch. Put power on one side and the light on the other side hook the other wire on the light to the other side of the power. You can use a propane torch to see if it shuts off the light when it gets up to temp. Use an oven thermometer to see the temp by touching it to the probe when the light goes out. Don't use the thermometer and the torch at the same time or the thermometer will break. The other way is to stick the probe into a pot of boiling water if it does not shut off the light it is either the wrong switch or it is no good. This method would be safer with a battery and a bulb rather than AC power. Water will boil at 212 degF


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Hotwaterwizard@aol.com John DeRosa "If I Can't fix it no one can."