If your radiator feels cold at the top but warm at the bottom, trapped air is almost certainly the cause. Air pockets prevent hot water from circulating fully through the radiator, leaving parts of it cold and your room insufficiently heated. This is an extremely common problem in New York City apartments with older steam or hot water heating systems. Bleeding a radiator releases the trapped air and allows hot water to fill the entire unit. The process takes just a few minutes per radiator and requires only a simple radiator key or flathead screwdriver, making it one of the easiest heating fixes you can do yourself.
Make sure the heating system is on and the radiators have been running for at least 30 minutes. This builds pressure that helps push trapped air to the bleed valve at the top of the radiator.
The bleed valve is a small metal fitting usually found at the top corner of the radiator opposite the supply pipe. It has a small square or slotted opening in the center.
Hold a small towel or container beneath the bleed valve to catch any water that comes out. Radiator water can be dark and stain floors or carpets, so protect the area below.
Insert the radiator key or flathead screwdriver into the valve and turn it counterclockwise about a quarter turn. You will hear hissing as air escapes. Keep the valve open until the hissing stops and a steady stream of water appears, then close it quickly by turning clockwise.
After bleeding radiators, check the boiler pressure gauge. If it has dropped below the recommended range of 1 to 1.5 bar, use the filling loop to top up the system pressure. Consult your boiler manual for instructions.
If bleeding does not resolve the cold spots, if you need to bleed radiators frequently, or if you notice leaks around the valve, contact a heating professional to check for circulation issues or a failing pump.
Call (646) 439-4057Bleed radiators at the start of each heating season and whenever you notice cold spots. Older NYC buildings with steam systems may need more frequent bleeding.
Frequent air buildup can indicate a system leak, a faulty pump, or dissolved gases in the water. If bleeding is needed more than once a month, have a technician inspect the system.
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