Expansion vessel performance

22 Dec 2020
Reaction score
United Kingdom
Hi...I need some help understanding an issue with my expansion vessel connected to my unvented cylinder. My understanding is the expansion vessel helps regulate the pressure in my unvented hot water system. Does the expansion vessel performance affect the central heating system?

Reason I ask is my installer is suggesting fixing a known fault with the expansion vessel as a way of solving my problem of banging central heating pipes. Just don't know enough to understand. Would appreciate if someone can help me out with an explanation
Sponsored Links
That was my understanding - so there is no connection between expansion vessel and central heating system?
Sponsored Links
Just have a white one - central heating has vaillant boiler - no vessel
Your boiler may be a system boiler which contains its own exp vessel, the two are in no way connected.
The expv on your unvented cylinder is there to accommodate the expansion of the water in the cylinder as the water is heated, it should have no bearing on on HW performance.
Other controls on the cylinder however may affect preformance.

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