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Riley

Plumbers Arms member
Plumber
Gas Engineer
Subscribed
Jan 14, 2013
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Sarf Coast
Hi All

working on one of these boilers at the mo

hot water is heating up to scalding point changed cylinder stat (which was dead) no difference

am now leaning toward issue with boiler but cannot work out what.

Phial was well out of position so have moved that back in.

Can't really understand how that would affect the hot water to the degree it is though

Do any of you have any pearls of wisdom
 
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Check out the motorised valve(s) if fully pumped.

Very likely that hot water side or valve letting by when heating called for.
 
A new thermostat might do it, the Phial is probably way outta range by now lol! I had a similar problem last year in the same boiler, it was gravity hot water & pumped heating. A replacement Ranco themostat did it... I noticed the customer had to keep turning the thermostat down lower & lower so that was a giveaway on mine.
 
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only by seeing if it shuts of at different settings i would start from cold set it to a low setting run it see if it turns of then go half way see if it still turns of probably easiest to change it if its fully pumped i would as above suspect valve letting by
 

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