The radiators that supply your home's hot water heat need to be bled occasionally. This is true for both standing and baseboard radiators. Bleeding radiators will ensure that air is removed so that water flows correctly through the system. It should be done every couple of months as a maintenance task or if the radiators do not seem to be working properly.
Ensure that the heating system is warmed up and at normal pressure.
Locate the radiator farthest away from the boiler system, and then find its valve. The valve is typically near the piping that enters the floor. On a baseboard radiator, the valve may be behind the small door on the end of the unit. On a standing radiator, the valve typically sits on top on the end of the unit.
Determine what type of tool you will need. Typically it will be either a flat-blade screwdriver or a radiator key.
Place the cup or bowl under the spout to catch the water. The space between the radiator and floor will dictate the size of the container.
Turn the valve counterclockwise slowly. Leave the valve open until only water (no air) is being released. Remember, your job is to get the air out of the system, not to drain a large amount of water.
Tighten the valve. Repeat the process at the next nearest radiator.
Return to the first radiator that you bled. Open the valve. If only water comes out, you have competed the task. If air comes out, return to the start of the process and repeat.