overheat thermostat

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jimb0jet

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• 23 Nov 2003

• #1

Hello,
I hope someone can tell me why the overheat thermostat regularly needs manual re-setting after several years of trouble free use. The boiler is a Potterton.

 

O

oilman

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• 23 Nov 2003

• #2

I hope someone can too, it's probably because the boiler is getting scale deposited around the noemal thermostat, and so the boiler gets hot enough to trip the o/heat stat. Try some on-line descaler, this just MIGHT help, but if it's lime deposits yyou will need to powerflush with an acid descaler. Best done in your case by disconnecting the boiler and doing it seperately. A job for the summer I think.

 

ChrisR

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• 23 Nov 2003

• #3

Could be, but could also be a faulty overheat stat! If you don't have kit to measure its cut-out temp, it might be worth trying a new stat. Also possible though less likely is a dodgy pump.

 

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oilman

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• 23 Nov 2003

• #4

Agreed, a faulty stat is more likely, it could also be a faulty control stat which is fairly easy to check.

 

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jimb0jet

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• 24 Nov 2003

• #5

Thank you for your help.

As it happened, the evening of when I posted the message, the boiler started to leak water.........heat exchanger packed up, electrics soaked to boot..........new boiler now. Much more expensive than a £10 thermostat

Thanks again for your input