Fluctuating pressure on a system boiler.

[Soggy_weetabix]

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.

David

 

[namsag]

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

 

[Soggy_weetabix]

Great stuff.

Thanks for your reply

Dave