Bleeding Your Radiators: A How-To Guide

If you have a boiler-style heating system that uses water rather than steam, there is an important maintenance task you should be completing about once a year – bleeding the radiators. When you bleed the radiators, you are letting out any air that has worked its way into the system, so the water is able to fill the radiators completely. Here's a look at the signs that your radiators need bleeding, and how to go about that process:

Signs Your Radiators Need Bleeding

  • One radiator is not getting hot, or the top part is cool while the bottom half is hot.
  • Your system has begun to make a lot more banging noises.
  • Certain rooms don't seem to be getting as warm as they once were.
  • It has been a year or more since you bled your radiators.

How to Bleed Your Radiators

Locate the key to your radiators. This key fits into the socket, which is typically located on the top or on the side near the top of the radiator. If you cannot locate the key, see if a flat-head screwdriver fits into the slot. If not, you'll need to visit a local hardware store and shop for a radiator key. Bring along a picture of the key slot on the radiator to help you find the right one.

With your system turned on, insert the key into the slot, and turn it just a little bit to the left. While you're doing this, hold a small container under the bleeding slot to catch any water that may trickle out. You should feel and hear air hiss out, followed by water. As soon as the water starts flowing, turn the key to the right again to close the valve.

After you have bled two or three radiators, go into your basement, and open the valve on the water pipe leading to your boiler system. This will let more water into the system, increasing the pressure so you can easily get the air out of the remaining radiators. After you've let the valve sit open for a minute or two, close it, and then go back upstairs to bleed your additional radiators in the manner described above. Make sure you open and close the pipe valve leading to the boiler between every couple of radiators.

After you've bled all of your radiators, your system should be back in working order. Put the key in a safe place until it's time to bleed them again.

For professional help with your heating system, contact a company such as Weather Crafters Limited.