Originally Posted by Ed Sirett

On Sat, 14 Jun 2008 16:05:25 +0100, Milsec wrote:

The expansion vessel has gone the boiler unfortunately. I say this
because water as well as air came out when I pressed on the valve. I had
hoped that the loss of circuit pressure was just due to a faulty PRV
(which also needs to be replaced).

It doesn't look feasible ( for me anyway) to remove the faulty unit due
to inaccessibility of the union nut and the inadequate clearance at the
top of the boiler prohibiting the removal and refitting of the vessel.


So I was wondering what size of external vessel I would need (the same
as the original?) and the best place to 'T' it in . I've read it goes in
the CH return leg of the pipework but are there any other factors to
bear in mind when fitting it? Do I have to stick with a Vaillant part
if there are cheaper alternatives?

As a matter of interest how does the pipe connecting the (original)
vessel fit into the rest of the boiler tubing, it looks like a push in
connector held with a clip? If this is all it is could I attempt to
remove it and connect the new vessel to this point?

Thanks all,

I presume you've read the FAQ on account of the questions you are now
asking.

You should be looking at about the same volume vessel as before (assuming
it was adequate); 12 litres should do it.

You need to find a suitable place somewhere on the return pipework.
Leave the failed vessel in the boiler. The official maintenance action
involves removing the boiler from the wall!
Set the new vessel to 0.8 bar on the dry side less/plus 0.1 bar for every
meter of altitude above/below the boiler.

HTH






--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html