British Gas rd532 combi boiler HELP please...

29 Dec 2010
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United Kingdom
Hi all,

I have a 4 year old british gas rd532 boiler. To date no problems at all... Xmas day CH mysteriously went off. I can reignite the boiler manually and all seems well for about 3-5mins.

Once temp rises to 95degC :idea: or so the boiler cuts out (normal temp much less than this)... I have narrowed this down to either CH pump (the most likely culprit) or the divertor valve (stop me if you think ive gone wrong so far!!)...

One last check I did was to bleed the rads and then drop the centre impellor screw from the pump to drain/bleed and also check. Seems to have rotation at this end (motor end I think this is?) but I guess the shaft could be broken? Before I go to much further does the above tally with a pump failure/blockage or shaft failure or should I give further consideration to the divertor valve?

Incidentally, since I didnt mention, hot water also hit and miss...

Thanks in advance guys...
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Yea it could be the pump, sometimes the impellor can dettatch and it may appear to be ok from behind the bleed screw it may not be spinning at the other end.

It could also be the diverter valve. If it was sticking in hot water position during heating demand it could give you this excessive temperature.

What pressure have you got?
Pressure now down to about 1bar now system bled and cold. Over xmas it had been redlining on pressure (2bar - 2.5 bar) before bleed of rads...
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