Central heating pressure

[agentgonzo]

I've recently had a bit of a problem with the central heating taking an age to get the radiators warm. It would take over an hour to get them to be hot.

When I checked the pressure in the system, it was set correctly at 1.1bar when running, but dropped to ~0.7bar when off. So I thought I would re-pressurise it when it is off back up to 1.1bar. Now the radiators heat up quicker (about 40 minutes to get to hot and about an hour to get to max heat - though it is 0° outside and it's been off all night). But when I read the guage just now it's up at about 1.7bar.

Should I pressurise the system to 1.1bar when it is off or when it is running?

 

[MANDATE]

pressurise when off and basically cool/cold. when on and water gets heated pressure will rise about 1 bar due to expansion.
going from 1.1 bar to 1.7 bar seems ok.
What you don't want, is for the pressure to reach 3 bar when heating on.
This can happen when expansion vessel has lost some or all of it's air charge which results in such a small volume of air for compression.
If and when 3 bar is reached it will for safety reasons open the PRV (pressure relief valve) which you don't really want cause they don't always close perfectly.

 

[agentgonzo]

Brilliant. Thanks. It seems to be working better since it has more pressure now

Off to play in the snow