In article ,
RossG wrote:
After returning from Christmas with the inlaws my neighbour informed
me that one of the loft overflow pipes had been dripping whilst we
were away. I decided to have a root around tonight when I put the
decorations away for another year and was suprised to find the water
in the expansion tank was hot!

We have a Baxi Solo 3 PF with a Honeywell Y Plan control system with
more than the minimum head stated in the installation guide. I then
remembered that the plumbed who last serviced the boiler muttered
something about the pipe layout not being particularly good and
causing turbulence in the flow pipe.

I'm guessing that the dripping overflow is simply condensation from
the hot water, however, why is the tank getting hot?

It's pumping over and should be seen to ASAP.

Has the system ever been properly balanced? (see FAQ) Is the pump speed
setting on anything other than low? All the pump is required to do is
circulate the water - speeding it up more than the minium needed to do
this is likely to cause pumping over. If reducing the pump speed to
minimum causes some rads not to work, balancing the system should sort it.
This is a fairly simple but rather time consuming task - but pretty
essential. A plumber could charge quite a bit for this because of the time
involved.

Only if correct balancing results in a rad or rads still not working
should the speed be increased.

Pumping over introduces air to the system resulting in much accelerated
corrosion. If you can't stop it after this, make sure the water level in
the header tank is only a couple of inches above the bottom, and consider
extending the vent pipe as high as physically possible - although of
course the opening must still be above the tank. Doesn't matter if it has
to go off at an angle to clear the roof joists.

--
*Real men don't waste their hormones growing hair

Dave Plowman London SW
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