Combi boiler and overheat stat trip problems
Ret.
is some 15 years old and has been causing them problems for some time.
Although the boiler runs the central heating without problem, as soon as a
hot tap is turned on, within seconds the over-heat thermostat trips and the
boiler shuts down.
In recent months the gas valve, thermocouple and overheat stat have been
replaced but the problem persists (in fact it is worse since the stat was
replaced!).
It seems to me that the over-heating is being caused because there is
insufficient flow of water through the heat-exchanger. We know that this is
not an issue with water pressure because this has been checked. The only
other thing I can think of that may be reducing water flow is that the heat
exchanger has become scaled up and requires replacing (although this is not
a hard-water area and kettles here don't scale up).
Because no gas connections are involved in this job, it is probably
something I can tackle myself - and, surprisingly, the heat exchangers for
this boiler are not over-expensive at between �119 and �170.
The big question is, however: is it worth spending out even more money in
trying to keep a 15 year old boiler going, or would the best course of
action be to replace the boiler? I don't know for certain that the heat
exchanger is the problem - and it would be annoying in the extreme if we
replaced it only to find that the overheat problem was still occurring.
Any advice welcomed - including any other suggestions as to why the overheat
stat keeps tripping when hot water is demanded.
Kev
ARWadsworth
"Ret." <xxx> wrote in message
news:9NCdnaA0MYK15kDX...@pipex.net...
You could check the fault finding part on the manual.
Adam
Ash
> It seems to me that the over-heating is being caused because there is
> insufficient flow of water through the heat-exchanger. We know that this
> is not an issue with water pressure because this has been checked. The
> only other thing I can think of that may be reducing water flow is that
> the heat exchanger has become scaled up and requires replacing (although
> this is not a hard-water area and kettles here don't scale up).
>
> Because no gas connections are involved in this job, it is probably
> something I can tackle myself - and, surprisingly, the heat exchangers for
> this boiler are not over-expensive at between �119 and �170.
The heat exchanger became scaled up on our combi a few yeas ago so I removed
it from the combi and carefully poured some brick acid into it and in no
time at all it was clear of scale and refitted. It's worked perfectly ever
since.
Ash
Ret.
Yes - my son still has the hard-copy and we've just been through it. It
appears that there could be other explanations for this problem. They've
decided to go for a new boiler!
Kev