Radiators warm the locations where they are installed by circulating water or oil through their fins, which warms the surrounding air. The liquid inside the radiators is pumped through the system by means of an electric pump. Occasionally, air gets trapped inside the radiators as it circulates. This makes your pump work harder and also decreases the heating potential of your radiators. Removing air from radiators is a fairly simple process. You'll soon have that warm feeling again.
Turn off your heating system. You can usually do this by turning off the switch on the heating unit itself. If there is no switch, cut the power for the heater at the main circuit breaker.
Place a towel on the ground around the radiator where you will be removing the air.
Open the valves on each side of the radiator.
Insert the bleeding wrench into the bleed screw opening. Turn the screw counterclockwise with the wrench. You should hear a hissing as the air escapes. As soon as water begins to flow out, turn the bleed screw back to its original location.
Fill up the radiator or boiler if needed.
If you don't have a radiator bleeding screw, you can use a wrench to loosen the nuts at the end of the radiator and let the air escape that way.