I have a VAILLANT - VCW GB 242 EH boiler installed by the previous previous owner and no manual.
When the heating comes on the pressure goes up to as high as three bar. I have read one cause can be insufficient air pressure in the expansion vessel. Can anyone point me in its direction please and can you confirm that is needs to be set at 0.65 bar (10psi). I am supposing it is internal but have only found the air intake at the rear on the RHS

simon2spanners, October 2009

john stop lying ya fag

ya daddy, October 2009

All combi boilers have an expansion vessel, Simon - unless its a very old type with a 4 gallon header tank somewhere.

John, October 2009

thanks for the quick response John.
I have seen I need to drain down prior to pressurizing the EV and had it drained today to swap out an old leaky TRV. You say 'if' it is connected, does that mean there may be no EV on my system?

simon2spanners, October 2009

The expansion vessel does indeed need to be filled to 10 psi. If its connected to the boiler, provision should be made to let water out of the EV as it is repressurised.

John, October 2009