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Ed Sirett
 
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Default Potterton Puma 80 Combi

glenn wrote:
=


Any suggestions as to the cause of the following fault.
=


Hot water is working OK.
=


Central heating switches on for 10-20 seconds, hot water emerges form h=

eat
exchanger into diverter valve and would appear to the enter the CH retu=

rn
side of the CH system (yes the valves are open). Water would just appea=

r to
be pumped around the combi `end` of the system. Water gets so hot, gas =

valve
cuts out.
=


Diverter valve (full) has been replaced, problem persists. CH is also f=

ull
of crap and would appear to need a good flush, this has been attempted
(possibly not completely flushed) but problem still persists.
=


Any experts with this combi ??
=


These boilers are a great boon to heating engineers and a bigger one to
the manufacturer who only sells the complete diverter valve (best part
of =A3100). =


If you had not had the diverter valve replaced I would say without
hesitation that the wax pellet acutator on the front end of the diverter
valve has gone tired and is not shifting the valve to CH mode. =


However the symptoms you describe are absolutely the same. =


1) A dripping HW tap can keep the actuator cool enough to prevent CH
coming on especially when the pellet is nearing the end of its shortish
life. =


2) Was it possible that the actuator was not replaced? Or the exchange
unit was not new?

3) Is it possible that all the radiators have TRVs and the temperture is
still too warm to let any circulation through the circuit?

4) The diverter valve can't move due to much debris (it would have to
be really bad for this). =


HTH

-- =

Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html