Trapped Air Keeps Radiator from Heating

Here is a common problem: The heat is on, but the radiator feels cold to the touch. This can be a sign that air is trapped in the system. In this situation, the radiator's air rises, keeping hot air from the top of the radiator. But the problem can be fixed easily: First turn the heat off. Find the radiator key and loosen the valve. It should be located at one end of the radiator. You should hear a hissing sound when you loosen the valve - this means trapped air is coming out. There may be some water dripping under the radiator so be careful when you wipe up the water, it may be hot. As soon as water begins to flow in the radiator, close the vent. The heating can then be switched back on.