Anthony Curren
This depends on the type of heating system you have. If you have a combi with a gauge on the front top up to 2 bar bleed radiators then top up again to one and a half bar. You will have to top up before bleeding each radiator. If you have a small tank in your loft for heating then you may have to turn off all radiators except the one you are bleeding this will help water get to that rad.