How to Bleed a Radiator in 8 Quick Steps

Before you start bleeding the radiator, there are a few things you’ll want to locate. Start by identifying the radiator on the first floor that is farthest from the boiler—even if you have one noisy or cold radiator, it’s best to bleed them all at the same time, and you’ll start with the one farthest away from the boiler. Then, locate the heat switch, as you’ll need to turn off your central heating, and locate the radiator bleed valve. This valve is usually at the top of the radiator on one of the sides.

Radiators can get pretty hot, and you don’t want to be touching hot metal while you’re trying to work. Not only that, but bleeding a radiator while the heat is still on could cause it to take in more air, and you’ll need to bleed the radiator again. Turn off the central heating, then wait about 15 to 20 minutes for the radiators to cool down. Note that you don’t need to know how to turn off a radiator for this step; shutting off the central heat will do.

While you don’t want to let out a lot of water, you can expect a little bit to dribble out of the bleed valve once it is open. To avoid an extra mess to clean up, simply lay a towel down around the floor beneath the bleed valve. You could also set up a small bucket here to catch any drippings.

Use the radiator bleed key to open the bleed valve. If you don’t already have a radiator bleed key, you can pick one up at your local home improvement store or order one online for about $5. Otherwise, you can use a flat-head screwdriver or needle-nose pliers to open the valve, turning counterclockwise just slightly, about half of a turn.

Now that the valve is open, you’ll start to hear a hissing sound as the trapped air escapes. At this point, a few drops of water may also leak out. This will take less than 20 to 30 seconds. You’ll know the bleed is complete when a stream of water starts to leak out.

When closing the valve, you want to work carefully. Tightening it too much could cause the valve to break off, particularly on older radiators. Use the radiator bleed key, or whichever tool you used to open the valve, and turn it clockwise for about half of a turn. This will tighten and close the valve.

It’s best to bleed all of the radiators at once, so after finishing up with the first one, move to the next radiator. You’ll want to work from the radiator farthest from the boiler, then move from radiator to radiator, getting closer to the boiler. If you live in a multistory home, start on the first floor following this pattern, then repeat the pattern on the next floor.

Once you’ve bled all of your radiators, turn the central heat back on. Now, your home should feel warm and cozy all throughout the rooms.