immersion boiler over heating Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[dstewart]

Hi, Hope you can help complete novice diy guy! Cental heating all working fine, as is thermostat on strapped to immersion tank ( I think), as hot water appear to be at appropriate temp and gas boilers clicks on and off at appropriate juncture. However, when I attempt to use electric immersion heater (instead of gas) to heat water, water is extremely over heated and tank begins to shake and is very quickly turned off! Is this a big problem to repair. I dont any more information due to recently moving into home.
thanks
Davie

[whelsy]

Sounds like the thermostat on the immersion element is set very high or is faulty.
Switch off all power and remove cap on top of immersion element,(On top or side of hot water cylinder) usually a single nut or screw.
Look for plastic chunk with an arrow pointing to a number.Make sure the arrow points below 65 (adjust with small screwdriver).
Re-fit cap and turn on power to recheck.
If water still overheats, sounds like you need a new immersion thermostat, better still replace element at the same time.
W

[DONFRAMAC]

The electric immerser has its own thermostat, lurking under the drum-shaped lid on the top of the fitting. This has a variable setting, which obviously is needing reducing to stop boiling. Newer ones have an overload trip which has a reset button, like that on power tools, mowers,etc. If the thermostat is broken, it can be easily removed and a new one obtained, --- get the correct length.

[dstewart]

on checking, my element has hole where thermostat perhaps should be ( I presume removed by previous home owner) I will therefore replace element.
Thanks
Davie