In article ,
Richard writes:
My Keston boiler seems nothing but trouble. In the two years since I
have had it installed, it has failed in the following ways

The main PCB failed (just stopped working)

The Keston system kit (expansion tank) failed- the membrane went

and now the cabinet overheats

Surprisingly the keston does not have a reset switch. Instead you have
to replace the 'thermal fuse' which is set at £4.50

They're around 50p each from CPC if this is the one on the transformer
connector block, but you'll have to know what the fusing temperature is,
and I've never looked at it that closely. Manual mentions 82ºC, but the
nearest standard values for thermal fuses seem to be 72ºC and 84ºC.

This is just to get the boiler to re-ignite. Then I surpose you have
to test it and see why the boiler overheated. Proably blowing one or
more of these thermal fuses. My local supplier tells me they do not
stock these items. Keston naturally do not supply direct, and I am
left with having to wait a week for this non stock item to appear (at
a charge of £18.50! (£14 small order carrage!) )

Therefore I am forced to call on Keston themselves to fix the problem.
It is going to be a very expensive repair (their MINIMUM is £150) as
at least their engineer will have the parts to hand, and will not be
on an endless cycle of get part, fit it , blow it discover real
underlying fault, get part fit it etc etc. I cannot wait weeks in this
weather.

Well, the thermal fuse failure is just a symptom of something
potentially more serious.

Let's try to guess what might cause the temperature in the cabinet to
overheat. Perhaps blocked air intake or flue, burst/split/disconnected
internal flue pipe, burst/split/disconnected internal condensate pipe
before U-trap (would also show up as water leaking from casing), failed
burner gasket, failed heat exchanger insulation (internal or external),
excessive combustion rate.

Also, are there any external influences which might heat up the boiler
casing, such as positioned over a radiator or some other heat source?
This could have blown the thermal fuse by overheating the boiler when
it's not running and there's no airflow through it.

So in conclusion. I cannot recomment kestion celcius 25s. Too flaky
Richard

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Andrew Gabriel