"dennis@home" wrote in message
...


"BigWallop" wrote in message
om...


It could be caused by a change in water pressure. Try turning the Hot
Water
Feed to the boiler completely off. Then demand hot water from the
boiler
(turn a tap on). Slowly turn the water back on until the pressure is
just
enough to get the boiler firing up to meet the demand. Once you have it
balanced on the sweet spot, it shouldn't give any more trouble. You may
have to turn the feed on a bit more if you have two taps demanding water
at
the same time, but do it slowly until the balance is met again.

I have had this happen on a couple of friends boiler systems, and it
worked
for us. I haven't heard them complain about it any more, anyway. :-)
So
I
take it that it's still working.



You will have to explain that one to me..
how does turning on the HW have an effect on the heating.
All the boiler should do is divert the heat to the water and then divert
it
back when the tap is off.
There must be something wrong with the diverting hardware for the problem
to
occur AFAICS.
He really shouldn't need to reset the boiler to get the heating back.


Central heating is on a closed loop, which means you fill the system with
water and then heat and circulate it around the house. Hot water is taken
directly from the supply, heated, then sent to the taps.

He is complaining about the boiler having to be reset if the central heating
is on and then he demands hot water. There are pressure difference switches
in the boiler. These detect if the boiler is giving central heating or hot
water. After demanding hot water from the boiler, the pressure difference
switch sounds like it is not canceling the request for hot water and not
allowing the boiler to change back to giving central heating.

The pressure of the mains water can cause the pressure switch to stay on
demand for hot water, even if the signal has been canceled. Simply
adjusting the incoming water pressure to allow the cancel signal to be
detected by the boiler can cure this situation.

It is a simple test to find out if this is the cause of the problem, instead
of pulling the boiler apart first to find out that it was just the mains
water pressure to hot water all along.

Clear enough?