bleeding radiator question-central heating left on

[jim1212]

I have always read that you should always bleed radiators with the central heating switched OFF.This was to prevent more air entering the system and causing potential oxidation and corrosion , further problems down the line.

Is this correct?

I'm a bit concerned because the boiler was serviced by a gas engineer,he then turned the central heating on and bled a radiator without switching it off again.



Cheers.

JS

 

[ALCPlumbing]

It won't cause a problem it's just that when you bleed the radiators when they are cold the water isn't moving as the pump will be off and as a result all of the air will have risen to the top of the radiator. Therefore you are likely to bleed more of the air out when it is cold compared to when the pump is running.

 

[jeff the gasman]

On older systems the pump was fitted on the return and often set too high for the required load. This resulted in air being drawn in at the vent when the pump was running.
Jeff.