"Antony" wrote in message
.. .
I've just moved into a 2 year old house and have discovered that the
boiler
seems to be playing up. It's a Baxi Solo 3 40 PF.

The problem is that the overheat light keeps coming on. The boiler
thermostat is set to maximum but I'm sure I read that this is the
recommended setting.

Any recommendations for things to try?

Thanks.....



Is it actually tripping, such that you have to press the manual reset button
to get it going again?

If so, it is overheating because the residual heat is not being carried away
fast enough after the main stat has cut the flame.

The first thing to do is to turn the main stat DOWN - it should not be on
max. This then means that when it goes off on the main stat, it can afford
to get a bit hotter without tripping the over-heat device.

Then check that the pump is wired correctly. This should be connected to the
boiler in such a way that the boiler keeps the pump running for a bit after
the boiler has stopped firing, in order to carry the residual heat away -
i.e. the boiler has terminals for pump connection, driven by its pump
over-run stat.

Then check that with all hot water and heating demands satisfied - but with
the pump still operating to cool the boiler (as above), the water actually
has somewhere to go. If the hot water and heating are each controlled by
separate 2-port zone valves, there MUST be a by-pass circuit to permit
circulation under pump over-run conditions. [If you have a mid-position
3-port valve, you probably don't need a by-pass UNLESS all your rads are
fitted with TRVs].

HTH,
Roger