How To Bleed A Baseboard Heater

Baseboard heaters provide warmth by heating water from a gas or propane boiler and distributing it through the pipes. Then, they transfer the water to the vents using a pump. If you experience inadequate heat or hear gurgling noises or a draining sound from the pipes, it may be time to bleed the system.

Bleeding the system removes air and sediments that build up that can reduce heat efficiency. Follow these steps to bleed the baseboard heater.

Prepare to Bleed the Baseboard Heater

To bleed the baseboard heater, gather:

  • garden hose
  • bucket
  • small bowl
  • towel
  • adjustable wrench 
  • Phillips and flat-blade screwdrivers 

Set the thermostat to 75 degrees, and let it run for about an hour. Turn the thermostat to the lowest setting, and shut off the power from the breaker or boiler switch. It is ideal to bleed the system in early fall or late spring, so you can open a window.

Locate the Bleeder Valve and the Drain Valve

Let the unit cool for about an hour. Look for the boiler drain valve with threaded connections that connects to a pipe or the boiler.  Find the inlet pipe that joins the water supply to the boiler, and use the wrench to turn the water shutoff valve to the right.

Find the baseboard farthest from the boiler, and look for a small bleeder valve on the end of the unit. The bleeder valve may be inside a panel on the end of the unit. Use the correct screwdriver to detach the panel screws.

Bleed the Unit

Set a bowl under the drain valve to catch water, and connect the hose to the drain valve, laying the other end outside or in a floor drain. If you drain outside, drain the water in a large bucket or pool.

Turn on the drain valve by rotating it to the left. Open the bleeder valve by turning the screw with the correct screwdriver, and keep turning until you hear air being purged from the system.

Watch the hose to see water pour out, and shut off the bleeder valve when it gets done. Don't leave the hose unattended to prevent the floor from being flooded.

Use the towel to sponge water off the floor. Repeat the process on the next closest radiator to the boiler until you bleed the whole unit.

Open the valve on the first radiator you bled. If water comes out, the system has been purged correctly, or repeat the process until you get water. Locate the barrel-shaped expansion tank on top of the boiler; set a bucket or bowl under it, and drain it in the same manner.

For more information talk to companies like Bill Rhiner's Plumbing, Heating & Cooling.