How To: Bleed a Radiator

By Scott Sidler December 29, 2014

Working on old houses in Florida, I don’t get much opportunity to work on radiators, so I’ve brought in a guest this week to share about how to bleed a radiator to keep your old house warm and toasty this winter. I know you’ll get a lot out of Jared’s post!

Jared Townsend is a Minneapolis based writer covering HVAC issues on behalf of Sedgwick, a provider of heating & air conditioning installation and repair services.

how to bleed a radiator
Copyright: soupstock / 123RF Stock Photo

This year’s cold season has already brought record low temperatures to many parts of the U.S., requiring home and other types of property owners to turn on their heating systems a bit earlier than usual.

Perhaps you’ve switched your heating system on and hit an unfortunate snag: One or all of your radiator units don’t feel like they’re producing the correct amount of heat needed to adequately warm your living space. Upon examining your radiator, you may notice that one side of the radiator feels hot, while the other doesn’t.

But before you go into panic mode, it’s important to thoroughly examine and identify a common culprit that may be contributing to the problem. Excess air may be trapped inside the system. If you have a hot water-powered radiator, it may be necessary to “bleed” your radiator – a process that can restore the unit to full functionality by getting rid of this air.

Bleeding Your Radiator

Bleeding your radiator is a relatively easy process that’ll free up trapped air inside the unit. Before you get started, you may need a radiator bleed key – a relatively affordable product you can find at the nearest hardware store.

Meanwhile, other types of radiators may only necessitate using a flathead screwdriver. Additionally, you’ll need a cup or towels to handle any excess water that may leak out from the bleed valve.

Follow these steps to successfully bleed your radiator:

  • Step 1: Turn off your central heating to avoid contact with hot water. Also, ensure that the radiator unit is off by turning the valve clockwise right. Allow the unit to cool to room temperature to maximize safety.
  • Step 2: Find the bleed valve on the radiator. These are typically located on the topside, are small, and may be circular in shape. In the middle they contain a bleed screw that’s often times rectangular. The radiator bleed valve is where the excess air will make its exit. We’ll need to open it.
  • Step 3: Insert the radiator bleed key into the valve (or flathead screw driver) and make sure that it’s secure. We’ll be turning the bleed valve screw.
  • Step 4: Slowly turn your tool counter-clockwise to successfully open the valve – while holding a cup or towel underneath the valve. You’ll likely hear a slight hissing noise as air makes it way out of the radiator unit. This will free your radiator of excess air that’s blocking the system from working efficiently. When you notice the appearance of water, turn your tool clockwise to close the valve. The towel or cup you have on hand will catch any excess water that seeps out.
  • Step 5: You just successfully bled your radiator. Now turn the heat back on. Inspect the unit to ensure that it’s working properly. Enjoy!

If this didn’t do the trick, this could be a sign of a larger issue dealing with the plumbing pipes or the hot water heater located in your basement area. When in doubt, contact a professional. And remember that safety is key.

 

Share Away!

4 thoughts on “How To: Bleed a Radiator”

  1. Scott,

    I have a 1925 home in Sunny/hot/swampy Orlando Florida, is there *value* in keeping this old system in place? We don’t know if they are operational- and we are installing a slim line on demand units down stairs and a traditional system up stairs.

    Should they stay or should they go?

    1. Tara, I have rarely seen a radiator in Florida! Whether it’s worth it to keep will depend on the condition of the costing system. Have a pro come out and inspect it so you know which path makes sense.

  2. Thanks for your article about how to bleed a radiator. I didn’t know that the reason why you would bleed a radiator wast to remove trapped air inside the unit. That’s interesting that for some models all you need is a flat-head screwdriver to perform this operation. I’ll keep that in mind should I ever buy a house or have a business that uses radiators. Thanks for the post.

  3. Interesting. But it would be nice if you Could specifiy we have to bleed the last floor before or it doesn’t matter. Mostly if the valves have been there for many years, untouched, it is not always a good idea to “play” with them.

    Cheers !

Leave a comment!

Keep the conversation going! Your email address will not be published.

*