Vaillant VCW 242 EH DHW expansion vessel

[paddy69]

Hi!
I have an old Vaillant VCW 242 EH. Can anyone tell me if the small expansion vessel for the DHW should have a charge in it?? It is only small but there is a schrader valve on it and pressing it lets no air or water out. Should this be pumped up to a certain pressure??
Thanks!
Phil

 

[DP]

Yes, it should have a charge in it. It is a small vessel so pressurising it will not be done with a foot or a cycle pump- moment you remove the pump, air will escape also

 

[Phill Peck]

It should have charge but u won't be able to recharge it.

The replacement valve requires this to be disconnected anyway.

What's the problem??

 

[paddy69]

Thanks!
I don't think this really has any bearing on my problems, just happened to come across it.
Main problems are: Expansion vessel gone! : Small leak on main heat exchanger. I did wonder if the leak has started due to over pressure with the expansion vessel gone.
Expansion vessel not a problem! But I gather I shouldn't be replacing the main heat exchanger with the spare I have as I am not Gas Safe registered!
Phil

 

[Agile]

Worse you should not even be removing the combustion chamber cover to look inside.

The small one should be pressured to the maximum of the water supply. But often supplied at 3.5 bar and not adjusted.

The problem is that removing the air pump lets a little air out from the joint and the small volume means that it loses almost all of its charge.

Taking it to some filling stations or using a compressor with a tank sometimes will work.

 

[Bunnyman]

Ignore the small vessel, it's of no use now and is not connected or used on the replacement water sections anyway

 

[Agile]

Worcester do actually require them to be fitted when there is a water meter or other one way valve.

Perhaps because they don't trust the strength of their plastic parts!

Tony