Fluctuating pressure on a system boiler.



Just wondering if anyone has experienced the same problem:

Glowworm System Boiler 18hxi I think. Could be wrong on the model.
Pressure at cold: 1 Bar
Pressure raises to 3 Bar as sytem heats up and prv blows (obviously.)

Check expansion vessel. Air released when operating the valve, so out comes the foot pump to check the pressure.

A fraction under 1 bar is measured, so it appears the e/v is charged correctly, but not tactually taking up any expansion.

This is the 3rd time ive had this fault on this boiler, and have remedied it by plumbing in a new expansion vessel externally on the system, charged at exactly the same pressure as the one on the boiler.

Once done, we're tickaty boo again.

Sponsored Links


Pipe to expansion vessel blocking or partially blocking. Thus in effect no expansion vessel.

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