In article ,
The Natural Philosopher writes:
wrote:
Thanks for your response.

So if i have understood you correctly, what I should have done to
relieve the pressure was drain by bleeding a radiator, not by opening
the valve at the bottom? oops. Do I still need to bleed the radiator?

The pressure is now remaining constant at 1.5 but does not seem to
fluctuate anymore, even when the central heating/hot water is in
operation.

If you have a drain anywhere its as good a way to relieve *pressure*..I
generally use a radiator tho, because the reason for pressure loss is
usaully that water has turned into gas by chemical action, and its the
gas that needs removing..I have tow rads that are classic 'gas traps'
these get bled every time I repressurise

The main reason for not using the pressure relief valve is
that it's very susceptable to getting any debris in the
water caught between the sealing surfaces, which will then
cause it to weep.

--
Andrew Gabriel