DIY Doctor UK DIY Forums

Hi,

New to the forum and hope someone can help.

Checked the system pressure on my Ariston Combi boiler today (for the first time in ages :oops: ) and it seems very low.

With the heating off it registers almost 0 bar (although the low pressure warning light isn't lit). With the heating on and pump circulating it rises to almost 1 bar.

I only checked it because I was in the loft (where the boiler is), not because of a problem. All radiaotors are piping hot with the heating on.

So:

1) Is 0 bar 'at rest' OK.
2) Should I bleed the system and/or get the pressure back up to 1 - 1.5 bar at rest or while the pump is working.

Thanks in advance.

AFAIK you should pressurise to 1 bar with pump off and system cold.

It should rise to about 2 bar when fully hot (due to water expanding and thus displacing the air in the expansion tank).