If you have hot or cold spots in different areas of your house, your radiators may need to be balanced. This is a great project for any do-it-yourselfer. With a few tools and some minor equipment, you can successfully balance your radiators and have your home evenly heated in no time.
Turn off the central heating system.
Bleed all the radiators in your home by inserting a bleed key into the lockshield valve and giving it half of a turn in the counterclockwise direction. The lockshield valve can be located at the top of the radiator near the edge. You will have to remove the push on or screw cap to get to the valve.
Turn the heating system back on while the valves on all radiators are open. Besides the lockshield valve, there will be another valve at the other end of the radiator. Depending on the age of your radiator, it will either have a wheelhead or thermostatic valve, both of which can be manipulated by hand. The lockshield valve will have to be turned with an adjuster.
Make a note of the order by which each radiator begins to heat.
Turn off the heat again and wait for the radiators to cool.
Turn the heat back on and report to the first radiator on your list. Turn the lockshield valve clockwise until it is completely closed. Then turn the valve counterclockwise a fourth of a turn. When the radiator has heated, take a temperature reading at the pipe connected to either of the valves. Then, take a reading of the temperature at the pipe connected to the other valve.
Open the lockshield valve until there is a 54 degree Fahrenheit difference from the first reading (12 degree for Celsius). Continue to adjust the valves on all subsequent radiators with the same method. The further away the radiator is from the boiler, the more you will have to open the lockshield valve. Once all radiators have been adjusted, they will be balanced and even heating should ensue.