DIY Doctor

Central heating system pressure

Postby dickiem » Wed Aug 15, 2007 4:30 pm


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.


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.
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Simply Build It

Postby corkee » Sat Aug 18, 2007 6:58 pm

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).
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