Installing an Expansion Vessel

10 Feb 2007
Reaction score
United Kingdom
When ever I have seen an expansion vessel installed it been with the valve uppermost, with the inlet at the bottom.
Surely this will trap air under the rubber diaphragm ?
Sponsored Links
When the system's cold the diaphram presses down to the inlet by the air pressure behind it (the cold pre-charge) and self purges any air that may have been caught when the boiler was running and the system was hot.

In a combi or remote EV system, the vessel wouldn't normally be the highest point in the system, there would usually be an auto air vent above the EV to vent air from the boiler circuit that would also minimise any air that would enter the EV.

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links