On Sat, 14 Feb 2004 18:51:30 +0000, Andy Hall wrote:

On Sat, 14 Feb 2004 18:22:06 -0000, "JohnB"
wrote:

Very very useful FAQ

My sealed system seems to have partially failed, ie I can keep it from going
over 3 bar by limiting the temp to 75C and keeping min pressure at about 0.4
bar.

I presume that the air will have leaked and needs pumping rather than the
diaphram holed - or am I just being hopeful!!

John



Try turning off the heating and remove the dust cap from the Schrader
valve on the expansion vessel. Release the pressure carefully as you
would to let a car tyre down.

If water comes out then you know the answer to your question and a new
vessel is needed. Otherwise, release the water pressure on the heating
circuit completely and then precharge the expansion vessel with a
suitable supply of compressed air or a tyre inflator. Finally
pressurise the water side again.

If you do have to replace the vessel, they come precharged with
nitrogen
.... to around 6 bar so you'll have to let some out.

A work around would be to drain a radiator in a spare room (if you have
one), but don't bleed the radiator, the air in the radiator will act as a
good expansion vessel until you can replace/add the real one.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html