How to Bleed a Gas Baseboard Heater

Baseboard heaters are steam-based heating systems that have a main boiler, typically in a basement. The boiler heats up water and distributes it throughout the home. The heated steam comes out at the baseboard vents near the floor in each room. Since the baseboards use steam, just as radiators, air sometimes gets trapped inside the pipes and causes banging noises. Eliminating the noise requires that you bleed the air out of the baseboards.

Dishtowel
Hexagonal bleed key or Allen wrench

Instructions

- 1
  Shut off the main boiler and wait until the water inside the system cools down before proceeding.
- 2
  Walk to one of the baseboard heaters and grasp its sides to lift off the front cover. Set the cover aside to provide room to work.
- 3
  Examine the side of the baseboard heater to locate the air bleeder valve. The valve looks like a small screw or cap and is located on the actual baseboard or on the water pipe that comes out of the floor.
- 4
  Wrap a dishtowel around the bottom of the valve to catch any excess water but do not cover the actual valve.
- 5
  Insert the end of a hexagonal bleed key or Allen wrench into the valve and turn it counterclockwise half a turn. You will immediately hear air hissing out of the valve.
- 6
  Monitor the valve closely until the hissing stops and water begins to trickle out of it. Insert the hexagonal bleed key back into the valve by turning it clockwise half a turn.
- 7
  Remove the dishtowel and wipe up any spilled water. Place the cover back onto the baseboard heater.
- 8
  Perform the same process on the baseboard heaters in every room to bleed air out of them. Then turn the main boiler back on.

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