Immersion thermal cutout

[J.C.E]

"oh my HW is not working"

Either 3 things, voltage not going through stat, through thermal cut out switch, or its not pulling any amps and change the whole lot. But recently I have been having to reset LOADS of thermal cutouts. I know they trip because it gets too hot. My question is, why do they get hot enough to trip?

 

[yellowvanman]

Maybe because the stat is not working properly!

Got a customer whos cut out regularly trips because of his solar thermal making the water too hot!

 

[Lighthouse Phil]

I have seen this problem very often. If they have another source of heat heating the cylinder, the water gets hotter then the stat is set to. I live in the country and use a back boiler to feed my cylinder in the winter, if the immersion switch is left on, the thermal stat will trip.

 

[ayjay]

use a tong tester on the live

 

[Edd]

Have had this where a Im heater has had the stat changed with one that has a resetable trip on it, continus tripping, all IR tests ok... Found to be that the tank was so old that the bottom Heater was not sitting in water but a pile of old scale 5 inches deap...Plumbers miss this even if they just change the element, as they are not expecting to see so much scale.