"andrewpreece" wrote in message ...
"sryley" wrote in message
om...
I've got a sealed central heating system that slowly loses pressure
over a period of a few days. I need to keep adding water to the system
otherwise the pump seizes up and my hot water and heating go off. I've
tried Fernox leak fix but no joy. I've got wooden floors and tiles on
top of the concrete floors, so identifying where the leak might be is
almost impossible, with no evidence of damp as a guide.

How can I go about fixing the leak or who could I get in touch with to
help? Local plumbers haven't come up with any bright ideas, just a
shrug of the shoulders when they replace my pump yet again.

Thanks in advance,

Simon

Check the leak is not in fact water being lost out of the overpressure valve
( should vent outside ) when the system fires up. To test, I'd suggest
repressurising the system, and watching the vent outlet when the CH comes
on. The underlying problem might then be your expansion vessel, which may
have lost its air charge. Just a possibility,

Andy.

Thanks for all the replies. Having found and read the plumbing FAQ it
does sound like the problem is with the release valve rather than the
pipes. I have used it in the past, and when I tried it again recently
it did change the rate at which the pressure was dropping. As
sometimes its over as little as 1 day but other times it takes a week
or more to drop to zero then that would suggest it wasn't the pipes?
(he says hopefully)

I saw the pipes go in and there was plenty of insulation around them
before concrete was poured. I was a bit worried as a big tree in the
back was chopped down which affected the foundations a bit -
doorframes started sticking the following year. I thought that might
have affected the pipes, or that I caused a leak when I turned the
pressure up past 3 bars once, at the time not knowing how much to turn
it up to when it had dropped. Could that have caused a leak or should
pipes be able to handle that ok? Does the variable rate of pressure
dropping suggest the release valve?

Many thanks,

Simon