System boiler external expansion vessel pressure

Joined
12 Oct 2016
Messages
25
Reaction score
0
Country
United Kingdom
I have a boiler (Worchester Greenstar Danesmoor System Utility 18/25) which is plumbed to a large Akvaterm cyclinder.

When the system is cold, the pressure gauge on the expansion vessel reads 0.75 bar. When the system has been running for a while the vessel gauge reads anywhere between 1.5 bar to 1.75 bar. My understanding is that when the system is cold the gauge should read 1 bar and when it is running it should read 1.5 bar. Is that correct?

I'm guessing that I need to pump a little more air into the expansion vessel in order to have it sitting at 1 bar when the system is cold. However, if my logic is correct, if I add air to the vessel using the schrader valve when the system is cold in order to bring the pressure up to 1 bar, surely afterwards, when the system is running hot the reading is likely to be higher than 1.75 bar considering that before I pumped air into the vessel it is already sitting at around 1.75 bar when the system is running, which is too high.

Therefore, if my logic is correct, does that mean I need to add air to the vessel to bring it to 1 bar when it is cold but then drain some water out of it to make sure that the pressure (when the system is running) is no more than 1.5 bar?

I hope what I've tried to explain makes some sense. If anyone is able to advise I would appreciate. Any questions just ask.

Thanks!
 
Sponsored Links
so what is your concern? does prv letting by? or boiler shutting off? don't bother touching it nothing wrong with it. why just get a local plumber to service your boiler and ask the expansion vessel as well
 
The lower the fill pressure on the EV, the lower the usable capacity. The PRV doesn't operate until it hits 3 bar, so I wouldn't worry about it too much, but the next time the system is drained down, check the EV and pump it up if necessary.
 

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
Back
Top