Bleeding a heater

[Emchelsea]

I have Gas central heating and one of the heaters is not working. it doesnt give out heat and doesnt even attempt to warm up.
I am wondering weather it needs bleeding but i have looked on pretty much all the DIY websites and cant find anything about bleeding a heater.

Can anyone help me?

[SteveV]

You can normally tell if a radiator needs bleeding by feeling the top and bottom. If it is air locked (and needs bleeding) the bottom should be warm, and the top should be cooler.

On one side of the radiator at the top is located the bleed point. You need a radiator key. Simply use the key to unscrew small square bleed nut. You may hear hissing as the air comes out. Bleed till water comes out then quickly tighten it up again.

If you find that water comes out straight away then it didn't need bleeding and the problem is somewhere else.

Check that both valves are fully open. They should be fully anticlockwise to be open.

Hope that helps.

[Swingset]

It is simple to bleed your radiators; you simply need to let the air out of the radiator by turning the radiator key. As you turn the key, air will be released, the water will push its way to the top, removing all the excess air and once a small amount of water comes out of the valve you should turn the key back. You should have a cloth ready in case the water is hot and to avoid any spillage.

If the radiator is cold at the bottom and warm at the top and this problem persists, then there may be some sludge at the bottom of the radiator and it may need flushing out. For this, the radiator will need to be taken off the wall, flushed out with water and refitted. This can be done by yourself if you follow the correct instructions and have a basic understanding of how your heating system works but if you have not done it before or are unsure of the procedure, then you will need to call a plumber or engineer out.

If several of your radiators have this problem and it is not solved by flushing the radiator out then the problem may be more serious. This could be caused by a fault with the circulating pump, blocked pipes or radiators or a badly designed system. You will need to call a professional out to look at this problem further as it may require the whole system to be flushed through or repairs to be carried out.

If your radiators are working correctly but are not hot enough or are too hot then you can alter the temperature by either adjusting the controls on your boiler or for more modern radiators with their own temperature controls, simply turn up or down accordingly.