On Thu, 3 Jul 2003 21:23:58 +0000 (UTC), "Nigel Percy"
wrote:

Hi,

Right all you knowledgeable persons. I moved house and am trying to get to
know
the various bits & pieces. What is the arrowed component in the following
picture

http://www.btinternet.com/~nigel.percy/heating.jpg

What's it for? How does it work?

Cheers

Nige


It's an automatic air vent. There is a high point in the pipework
where it's fitted which would otherwise accumulate air.

Inside the brass chamber, there is a little plastic float, normally
with a lever with a rubber disc on the end. The disc covers a hole
in the top of the chamber, which in this case has a second cover on
the outside - the red cap. Air will tend to go up the vertical pipe
and to the chamber and the float will drop, opening the hole. Thus
the air escapes, water rises as does the float and the hole is closed.

These valves are not always perfect in sealing, so the red cap is
there as a means to prevent escape of water that is not known about.
You can check if there is accumulated air by turning the red cap
anticlockwise. You may get a few drops of water as the valve closes
if there is accumulated air.



..andy

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