Megaflow Immersion Heater and Thermostat Shorting

29 Oct 2014
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United Kingdom
I have a problem with a Megaflow Direct Immersion Heater and Thermostat shorting.

When the immersion heater is switched on, its shorts with the thermostat and there is a bang/flash and the fuse blows.

I thought it was a faulty TSE thermostat but having replaced the old thermostat with a new one, the problem still happens.

The short appears about 3cm from the head of the thermostat (see photo)

I have checked the resistance of the immersion heater and it is around 18 ohms, which appears to be correct.

Any ideas anyone can give would be much appreciated.
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You may have measured the element resistance but have not measured that actual fault resistance.

Obviously something is causing the thermostat rod to be come live and that is shorting against the earthed pocket.

I can only guess that there is an "earth" connection to the TSE and that has become live.

However, to identify the fault it will be necessary to measure live voltages applied to the TSE and as there is a known fault then that is likely to be a potentially dangerous situation which I should not even suggest that you do!


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