Bleeding a radiator is not too difficult to do and is done to expel air that may have got into the system after maintenance or a radiator change. Professional help from a Swiss Cottage Plumber is always a recommended way to carry out such work if you are unsure and will also guarantee the work is done correctly.


Method:

Firstly isolate the circulation pump which can be done by shutting the isolating valves either side of the pump. You can turn off the boiler, although it is not essential to do this. All radiators will have a bleed valve on one of its top corners, identifiable by a square-section shank in the centre of the round blanking plug. You need the right key to fit the shank. Installers such as Swiss Cottage Plumbers have these. If you do not have one, they can be purchased from any DIY shop or plumbers merchant. With the key turn the valve’s shank anticlockwise about a quarter of one turn. You should not need to turn it further, however, have a small container handy to catch any water, in case you open it too far.


Don’t try to speed up the process by opening the valve further than necessary. It will hiss as the air leaves. Keep the key on the shank of the valve, then, when the hissing stops and the first dribble of water appears, close the valve tightly. If no water or air appears when you bleed a radiator, check if the feed and expansion tank in the loft is empty. If it is full of water, then the bleed valve is possibly blocked. Shut the inlet and outlet valve on each end of the radiator. Now remove the screw from the centre of the bleed valve. Clear the hole with thin wire, and re-open one of the radiator valves slightly and eject some water from the hole. Shut the radiator valve and fit the screw back in the bleed valve. Open both radiator valves and try again.