"" Skip to Content

Baseboard Heater Bleeder Valve

Baseboard heaters are floor-mounted devices that radiate heat upward. They have bleeder valves. A baseboard heater bleeder valve forces out the air that builds up in the baseboard heating system. 

My neighbor lives in a classic house with a baseboard heating system. Heaters are set up underneath exterior windows in these types of houses. As soon as cold air comes in, the baseboard heater pulls it in and warms it up before releasing the hot air back into the room.  A few months ago, my neighbors mentioned a problem with their heating system. 

I volunteered to assist since they are an elderly couple, and I am a passionate heating, ventilation, and air conditioning (HVAC) enthusiast. Their baseboard heater made noises, so I knew I needed to bleed it. 

In this article, I discuss bleeder valves, baseboard heater advantages and disadvantages, how to bleed a baseboard heater, and how to replace one. I additionally cover how to bleed your radiator if it displays the same problem. Finally, I list common additional baseboard heater issues. 

What Is A Baseboard Heater Bleeder Valve?

baseboard heater bleeder valve

A bleeder valve is a valve that removes trapped air from the baseboard heater. Air bubbles accumulate and prevent hot water from flowing through the baseboard heater. The tiny valve is visible on the piping next to the baseboard. 

However, how do you determine if your baseboard heater contains air bubbles? You’ll notice the following signs: 

  • The room’s air is not warming up.  
  • Odd noises, such as bubbling or gurgling, from your baseboard heater. As hot water passes through the system, it tries to avoid air pockets, which causes the noise.
  • A decline in your baseboard heater’s overall efficiency is another sign that there are air pockets. Either the temperatures are inconsistent, or your heater takes longer to heat the space. The hot water cannot heat your rooms because of the air trapped inside the system. 

Even while the signs above or others don’t necessarily indicate that you need to bleed the baseboard heater, they nevertheless indicate a problem. It is unavoidable that you will need to bleed the baseboard heater if you experience those symptoms and your thermostat is reading high.  

Your baseboard heater can operate efficiently once all the air expels via the bleeder valve. You can prolong the time your baseboard heater can operate efficiently by frequently bleeding it. 

The Advantages And Disadvantages of Baseboard Heating

Baseboard heaters usually have hot water or hydronic baseboard heating installed with radiant flooring. The heaters use a boiler to transfer hot water through numerous pipes from one heater to another. A hydronic heater system works well without charging because it retains the water inside the system. 

Below are some of the advantages and disadvantages of baseboard heaters. 


  • The baseboard heater runs quietly. Unlike forced air systems, which emit noise as they blow air. The bedroom, where you need the most peace, is ideal for installing a baseboard heater. 
  • Baseboard heaters are simple to clean with a vacuum. For example, they don’t need as much maintenance as more complex HVAC systems.
  • Baseboard heater installation is easier because ductwork is not needed. 
  • Baseboard heaters are less expensive to install, particularly if you only need to heat a small room. The heater is affordable if you need an extra heat source for a big house. 
  • Baseboard heaters are a safe heating solution for your home. 


  • Baseboard heaters occupy space along your baseboard, which restricts the room you have for furnishings. 
  • The heaters often become extremely hot. You must leave a clear area around the baseboard heaters to prevent a fire from igniting or damaging other items in the room. 
  • Other non-electric heating options are more cost-friendly than baseboard heaters. 
  • Baseboard heating might not work well if you often adjust your thermostat. If you frequently adjust your temperature, the heaters cost more to run.

How To Bleed A Baseboard Heater

baseboard heater bleeder valve

Confirm the baseboard heater system is off and cooled down before beginning bleeding. You don’t want to get burns when you attempt to bleed a baseboard heater. The heater will release high-pressure hot water. 

Always have a small container ready to capture any water the baseboard heater may release. You can bleed the baseboard heater by following the process below. 

  1. Locate the baseboard heater bleeder valve on the baseboard heater. Place the container underneath. 
  2. You can then slowly open the bleeder valve using the bleeder valve key or a flathead screwdriver. 
  3. As you open the bleeder valve, the air trapped in the baseboard heater system will begin to escape. Most likely, you’ll hear a hissing noise.
  4. Once you notice the water flowing steadily without air bubbles, close the valve immediately. That means there is no more trapped air in the system. 

You can now turn on the system and check if the heating quality has improved. The room will become warmer if air blockage is the problem. You should continue to bleed regularly. 

How To Perform A Baseboard Heater Bleeder Valve Replacement

If you notice that a bleeder valve is faulty, the solution is to replace it as soon as possible. Before starting the work, confirm that you have a Teflon tape or paste for use as a thread sealant. 

Now, let’s move to how to replace a baseboard heater bleeder valve step by step: 

  1. Turn off the boiler.
  2. Close the boiler’s manual water feed valve. 
  3. Attach a hose or use a bucket to release the pressure from the boiler. You avoid having water coming under pressure from the fitting in this way. 
  4. Wrap the new bleeder with Teflon tape and keep it ready to install. 
  5. Clean the fitting after releasing the pressure. Thumb over the hole to carefully remove the old bleeder valve, then swiftly screw the new bleeder valve in. 
  6. Teflon tape shouldn’t extend past the fitting’s end. Keep it a couple of threads from the end. Don’t wrap the tape more than once. 

How To Bleed A Baseboard Radiator 

Baseboard radiators don’t heat the air around you; they transfer heat through radiation by warming up the objects in the room. The objects then warm the air in the room. On the other hand, baseboard heaters use convection currents to heat the air directly.  

There are two types of bleeder valves on the radiator: manual and automatic. The automatic bleeder valve reacts to air buildup by forcing open the valve and letting the air escape. The manual baseboard radiator bleed valve requires your intervention. 

You can follow the steps below.

  1. Let your radiator heat up by turning your boiler to the highest setting. When it feels hot, shut the entire system off. 
  2. Find the air bleeder valve starting with the radiator closest to the boiler. You will find the valve on top of the radiator or piping. 
  3. Put a container beneath the valve to catch any water that may leak, and have a towel close by. Open the radiator bleed valve gradually with a flathead screwdriver or an air valve key. 
  4. A hissing sound indicates that the trapped air leaves when you open the valve.
  5. Once the hissing sound has stopped, close the valve immediately. 
  6. For all of the radiators in your home, simply repeat the instructions above. Check the boiler’s gauge to confirm that the water pressure is normal after bleeding every radiator. Restart your heating system.

Before bleeding your radiator, it is vital to ascertain whether it is steam (which doesn’t need bleeding) or hot water. For steam systems, just one pipe enters each radiator. There should be an air vent on the side of each pipe. The radiator problem will clear when you clean the vent. 

For water to circulate through and return to the boiler, hot water system radiators have two pipes. One of them has an electric circulation pump linked to it.  Remember, radiators are fire hazards if you install or operate them incorrectly. 

What Are The Common Problems Of A Baseboard Heater? 

baseboard heater

Usually, a few little air bubbles in the water go into the baseboard heater. If the air bubbles don’t merge, they won’t cause problems. A hydronic airlock forms when the microscopic air bubbles combine due to repeated heating and cooling. 

That implies that as the air in the system builds up, the water will stop flowing. When you notice that your baseboard heater is not getting warm, it is faulty. 

However, as you can see from the table below, numerous issues might stop your baseboard heater from operating: 

Baseboard Heater ComponentProblemSolution
The circuit breaker trips instantly.You have a short somewhere in the system.Replace the fuse in the breaker box.
Call a pro to upgrade the circuit breaker or replace the wiring.
The baseboard heater does not turn on.Something is blocking the vents.Remove any furniture or anything else that could be obstructing the vent.
There should be space a few inches above and in front of the heater.
Check the heater’s internal valves.
Lubricate the valves to stop rusting and sticking to one another.
The baseboard heater does not turn off.The thermostat has a problem.To unblock the contact, tap the thermostat for a short-term treatment.
Replace the thermostat.
The heater produces a burning odor.Hot air-burning lubricant or dust that has collected on the vents.Use a towel to clean the vents after turning off the heat.
Vacuum the fins.
Call a specialist or replace the heater if the smell persists.


You can keep your room warm using baseboard heaters. However, air bubbles might build up and keep the heater from functioning correctly. The baseboard heater bleeder valve is the only way to eliminate the air bubbles trapped inside the heater. 

I hope that after reading the insights in this article, you feel confident to perform baseboard or radiator bleeding independently. However, consulting a professional is always preferable if you can’t manage to do it yourself to prevent damaging the whole system or getting injured. 

Frequently Asked Questions

1. What is a baseboard heater bleeder valve, and how does it work?

A baseboard heater bleeder valve is a little valve that aids in removing air buildup from your heater. After shutting off the heater, gradually open the bleeder valve to release any trapped air. 

2. What are the signs of a faulty baseboard radiator bleed valve? 

You will hear gurgling or bubbling when your baseboard radiator’s bleed valve malfunctions. Your room has less heat, or it takes longer for your heater to heat it. A high reading on your thermostat will indicate that your baseboard heater is faulty.

3. Why is it important to bleed a hot water baseboard heater, and how to do it correctly? 

The hot water baseboard heater malfunctions because air bubbles build up inside the heater. The air bubbles prevent the system’s hot water from moving through it. However, you can bleed the heater using the hot water baseboard heater bleeder valve. So, the air bubbles are gone. 


  • Jonah Ryan

    Jonah has worked for several years in the swimming pool industry installing and repairing equipment, treating pools with chemicals, and fixing damaged liners. He also has plumbing and electrical experience with air conditioning, ceiling fans, boilers, and more. When he's not writing for Temperature Master, he's usually writing for his own websites, LawnCareLessons.com and DIYByHand.com.

As an Amazon Associate, we earn from qualifying purchases. We may also earn commissions if you purchase products from other retailers after clicking on a link from our site.