ariston boiler pressure up and down

[pingu666]

hi all, suffering with the dreaded ariston combi again.After replacing a faulty prv i repressurised the system to just below 1 bar.When heating is on this rises sharply to nearly 2.5 bar, is that right.Also noticed when hot water is drawn the pressure drops by about 0.5 bar.Can anyone point me in the right direction.Cheers

 

[Gasguru]

Read the FAQs on expansion vessels.

Quite normal for the pressure gauge needle to move a little with a DHW demand...especially on the Microgenus range.

 

[Ray84]

yeah your PRVs probably only went faulty due to the underlying problem with the expansion Vessel.

Ray[/u]

 

[pingu666]

cheers guys was thinking the expansion vessel just wanted to confirm it