On Tue, 14 Sep 2004 11:31:53 +0100, Christian McArdle wrote:

"Components:

A filling point.
A pressure relief valve and discharge pipe.
An expansion vessel
A pressure gauge"

"Automatic air vent" should be one of these points.

There is no requirement for an automatic air vent on a sealed pressurised
primary circuit. Sure, they're very useful and labour saving, but many
systems do not have them installed.


Although combis are invariably sealed systems and invariably contain an
automatic air vent I did not consider that they were an _essential_ part
of a sealed system.

--
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