Boiler pressure

georgez

Hi, really confused. When switched off, my boiler pressure is zero. But, when i switch the heating on, the pressure rises and everything seems to work as normal ie radiators ok and hot water ok. Should I still be concerned, don't want to cause any damage to boiler. Thank you

TeamPlum

When you say switched off, do you mean 'without power' or do you mean 'the central heating isn't on'?

I wouldnt be concerned as boilers will disable themselves when pressure is too low

MikeEngTech

Not all boilers have a low or high pressure cut off. If it!!!8217;s below 0.8 bar when cold then top it up. If it climbs above 2.5 then you need to call someone out.
Your boiler will have user instructions that will tell you want the pressure should be.

malky39

Most boilers will sit at about 1-1.5 bar when cold/heating is off. When the heating is on this will rise maybe by 0.0-1 bar. But should never go over 3 bar, or as mentioned you have other issues going on. When the boiler is cold top up the pressure to about 1-1.5 bar. Then leave it to run. You may want to bleed the rads at the same time as doing this.
The hot water is not affected by the pressure.

boliston

malky39 wrote: »

Most boilers will sit at about 1-1.5 bar when cold/heating is off. When the heating is on this will rise maybe by 0.0-1 bar. But should never go over 3 bar, or as mentioned you have other issues going on. When the boiler is cold top up the pressure to about 1-1.5 bar. Then leave it to run. You may want to bleed the rads at the same time as doing this.
The hot water is not affected by the pressure.

Surely the system pressure needs a basic level of pressure eg 0.5 bar for the heat exchanger to work?