Topping up CH Combi Boiler

[ls177hq]

Hi, I have an Ideal Mini boiler and when the central heating is off the water pressure shows as being almost zero bar. Is this right, I recently bled the radiator in the attic and air came out but no water despite waiting ages. It seems to be working ok heat wise but I don't want to cause long term damage. Thanks

[gasman]

You need to top up the pressure immediatley to approx 1 BAR (when cold) .

[Octavius]

Yes, when the heating is on the hot water expands so the pressure would normally go up. You need to get water into the system, then bleed all the radiators (top down) until water bubbles out, and if need be get water into the system after each radiator check as necessary. As gasman has said, do this when the system is cold.

[ls177hq]

Hi

Thanks for the fast response, I was concerned but I'm just waiting for it to cool down and I'll sort it out. Final question, do I bleed the radiators when the systems cold?

[gasman]

You can bleed them anytime, But the pressure will be greater when hot due to the thermal expansion in a sealed system. So to gain an accurate pressure guage reading it is best recorded when cold. Hot it could be anything upto approx 2.5BAR.

[ls177hq]

Again, many thanks Gasman.