How to Bleed Baseboard Heater (4 Simple Steps)

Michael J. O'Connor
By Michael J. O'Connor  • Reviewed by Ben  • Updated:   December 12, 2023
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Nothing is more important than keeping your home comfortable when the weather gets cold. 

If you have a baseboard radiator heating system, it is essential to maintain it. Staying on top of its upkeep will ensure that you can heat your home without interruptions in service. 

Now and then, you have to bleed your baseboard heating system to see if it will run efficiently. Fortunately, this is a relatively easy process that almost anyone can do.

Knowing how to bleed baseboard heat systems will keep your home warm and prevent problems with your system in the future. 

Why Do You Have to Bleed Your Baseboard Heat System?

Most baseboard heating systems use radiating heat to warm up your home. 

These systems take hot water from the water heater and distribute it throughout the different radiators within the house. 

After a while, though, these individual radiator units will get buildups of water and air. 

When this happens, new hot water can’t flow through them, and they will stop heating up. Knowing how to bleed baseboard heat systems is essential if you are going to prevent cold spots in your home. 

How to Tell When You Need to Bleed Your Baseboard Heating System

The most obvious indicator that you need to bleed your baseboard heating system is persistent cold spots. 

If you notice that certain rooms aren’t getting warmer when you turn your thermostat up, this could be a sign that you need to bleed the radiator units. 

In some cases, you may also notice gurgling or spurting noises from the radiator units. This happens when the trapped air and old water block the new hot water. 

Releasing the trapped air and water through the bleed valve usually solves this issue. Knowing how to bleed baseboard heat systems in your home will help prevent cold spots and keep your system in good working order all year. 

How to Bleed Baseboard Heat Systems

You can start the process once you have identified that you need to bleed your baseboard heat system. 

I always recommend having a handy receptacle like a cup or bucket that you don’t mind getting dirty water into. When you bleed the unit, water that may have been sitting in the radiator for a long time will come out. 

You should also keep your hands safe as you are bleeding the valve. 

The water may come out fairly hot depending on how long it has been since the radiator has been blocked. Wearing gloves will protect your hands and give you better control as the water comes from the bleed valve. 

With a good understanding of how to bleed baseboard heat systems, you can keep your units in good condition and warm your home. 

1. Turn the Heat On 

Before you get started, turn the thermostat up on your heating system. 

Keep it at the same temperature you usually have when it is the coldest time of the year. This will get your radiator units warmed up to their average temperature. 

You will most likely notice that your water heater kicks on. If you can see any of the water lines leading from the heater to the radiator, listen and watch as the water flows through them to see if any areas might be blocked or leaking. 

You can move on to bleeding the radiator units if everything flows well. 

2. Feel and Listen to Each Unit

Go to the rooms that seem to be lacking heat the most. 

Carefully feel the radiator units located at the baseboards, starting from the bottom. 

The bottoms of the units should be hot. If the unit gets cooler as you move to the higher points, this is a sure sign that you need to bleed it. 

This inconsistent heating usually means that there is air or water trapped in the top of the unit, and it will need to be bled. 

You should also listen for any kind of gurgling and sputtering within the units. Knowing how to bleed baseboard heat systems will be very useful if you hear unusual noises that sound like water or air trying to flow unsuccessfully. 

3. Open and Drain the Bleed Valve 

Most modern radiator units have a bleed valve on the side that can simply be turned with your hand. 

Put your catch cup underneath the valve and open it. The water should be completely drained out of the unit in a few minutes. 

Some older radiator units have bleed valves that require a key. 

Your home may have come with this key, but if it did not, you can usually purchase it at any hardware store. 

If you can’t get a key for your bleed valve, you can almost always open it using needle nose pliers. I recommend that you always wear hand coverings if you are opening your bleed valve this way, as the water can come rushing out faster than you expect.  

4. Test the Heat 

Once you have bled the radiator unit completely, be sure to tighten the valve. 

Turn the thermostat up again to get the heater to kick on. Listen for any strange noises, just like you did before bleeding the unit. 

Once the heater has been on for a few minutes, feel the radiator unit again. It should have even heating throughout with no cold spots or areas that sound like they are sputtering. 

Final Thoughts

You have to keep your home warm during the winter months. If you have noticed that some of your rooms aren’t heating up like they should be, it could be because the baseboard heating units need to be bled. 

Knowing how to bleed baseboard heat systems lets you keep your home warm and comfortable throughout the winter. 

Hey there! I am Benas, the founder and content editor at Home Caprice. Thanks for reading the article. I hope you were able to find what you were looking for. I and my team are here to simplify heating and cooling for everyone. Please have a look at the About page for more details about our website and feel free to check out our editorial process.