John Rumm wrote:
On 01/04/2018 15:44, Richboiler wrote:
Hi - I've had a gas fitter out twice now to repair it but its still not
sorted. The boiler fires up ok but after 30mins turns itself off. The
central
heating pump has been replaced and the gas valve. After the fitting of
the new
gas valve it ran ok for 5 days but then has gone back to square one. Any
ideas?... I've been in touch with Potterton/Baxi to see if II could get an
engineer to come out but they don't support this model any more - the
boiler
is 14 years old and I'd like to repair it rather than replace it.

You need to go through the controls step by step to isolate where
something is not working.

So starting with the call for heat signal to the boiler... Does that
stay on when the boiler shuts off? If not work back checking the output
from the zone valve, then the stat and then the programmer.

If the call for heat is still on, then check the call for heat at the
gas valve itself... if that is present, then the gas valve must be
faulty. If not then check the output from the internal stat. If its got
a fan then look for the signal from the air pressure switch. Keep
working through looking at the chain of dependencies. Is there
electronic flame sensing? Is that working or is it detecting a flame
failure.



Other thought, could it be a low flow problem (leading to overheat)? System
may be clogged up.

Tim

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