Knowing how to bleed air from a baseboard heating system is a must if you own such a system. The reason is that trapped air in the pipes is a prevalent problem. You may not encounter it every heating season. However, rest assured of running into the issue every few years.
If you know how to bleed the lines, you wouldn’t need to spend the night in the cold or pay close to $100 for an HVAC pro to fix the problem.
The best part is that it’s easy to tell if your baseboard heater has water trapped in the lines. Some of the signs are;
- Gurgling or other odd sounds coming from the radiator or plumbing
- A sound like draining water coming from the heating pipes
- Insufficient heating. The baseboard or radiator won’t heat up adequately.
A baseboard heater with water trapped in the lines can also become utterly defective if the issue isn’t resolved fast.
How Does Air Get Trapped in the Baseboard Heater?
If you’re wondering how air gets trapped in baseboard heater lines, it’s because baseboard heaters and other water-based heating systems have air particles trapped in the water and even more air lurking around the lines.
The first problem is usually minor but becomes more serious over time. Air particles trapped in water are only tiny particles that pose no threat to the baseboard system individually.
However, over time, as the water moves about the baseboard lines, the air particles can combine to form larger bubbles. Then the big bubbles may also combine to form even bigger bubbles, eventually causing a hydronic air block.
A hydronic air block occurs when air builds up in your hot water system to the point of blocking water from circulating.
Most baseboard heaters and boiler systems have a built-in air management system to get rid of air blocks or prevent them in the first place. Boiler water loops, for instance, are explicitly designed to prevent air blocks.
The second issue is even more common, especially if your baseboard heater loses its airtightness. The baseboard heating system is supposed to be completely airtight.
However, over time, gaps may form at the various joints. As expected, these gaps can result in water leaks. However, they may also serve as entry points for lurking air.
How to Bleed a Baseboard Heater
Bleeding a baseboard heater is a straightforward process if you have the requisite tools and knowledge. You’ll find air bleeders on the radiator or the piping near the baseboard in a properly designed system.
The bleeders are easily accessible and easy to use, though they come in different shapes and designs, thus requiring unique tools and keys to bleed air from the baseboard.
Assuming that your baseboard heater has a bleeder valve, proceed as follows to rid it of air trapped in the lines.
- Turn ON your baseboard heater: Although it feels more sensible to have it OFF for the bleeding process due to safety reasons, bleeding is only possible when the baseboard heater is up and running.
- Locate the bleeder valve: Head to the baseboard radiator that’s furthest from the boiler and locate the bleeder valve. The exact location will depend on the type of baseboard heater. However, it’s usually near the top of the radiator. You’ll also know you’ve found the bleeder valve if you come across a valve that’s meant to be opened using a key or a simple flat-head screwdriver.
- Position a container under the valve: A large cup will do in most cases. However, to avoid any surprises, you may use a jug instead. This container will help you collect the water draining from the line, so you don’t wet the entire area.
- Loosen the bleeder valve: You don’t want to open it. Instead, the idea is to loosen it so that air “bleeds” out without the water gushing out as well. So, turn it anticlockwise until water begins to drip from the valve. Then stop. You’ll notice air coming out together with the water. That’s what you’re interested in, not the water.
- Let the air bleed out: Wait for several seconds for the air to come out of the lines. It might even take a few minutes. Sometimes the air is so much that it comes out with a powerful hiss. However, other times you may only see tiny bubbles around the valve.
- Re-tighten the valve: Once all air has come out, re-tighten the valve by turning it clockwise until it’s tight enough.
- Repeat for all baseboard heaters: Many homes have more than one baseboard heater. It’s wise to set aside a day to bleed all your heaters. All you need to do is repeat steps a-f until you’ve covered all the baseboard heaters.
How to Bleed a Baseboard Heater without Bleeders
Yes, you can bleed a baseboard heater without bleeders. It’s a slightly different process that requires even greater caution. However, it’s been done before, and you can do it too – without professional assistance.
Step1: Confirm the absence of the bleeder valve
Begin by confirming that, indeed, there’s no bleed valve on the baseboard heater. Sometimes the valve can be hidden in completely absurd places, such as somewhere in the basement or bathroom. Or, it may be somewhere else along the pipe.
The best way to fully confirm that you don’t have a bleeder valve on your baseboard heater is to follow the pipes from end to open.
Step 2: Locate alternative valves on the baseboard system
The good news is that no baseboard system is designed with at least a few valves. So if you can’t locate the bleeder valve, the chances are that the manufacturer has an even better plan for bleeding the baseboard.
For instance, many baseboard manufacturers integrate an automatic valve into the heating system to make your work extra easy. The automatic valve isn’t a substitute for bleeding a system manually, nor is it an excellent remedy for bleeding a system that’s choked with trapped air. However, it’s an excellent and valuable way to release trapped air from your baseboard pipes.
The valves are installed at a high point of the system where trapped air typically collects. However, they may also be found anywhere else in pumped-water systems. They are installed with the first installation of the system and last the life of the system.
The bottom line is that the automatic valve releases air trapped in your baseboard system automatically. The valve doesn’t wait for you to begin bleeding. Instead, it monitors the system and automatically releases trapped air whenever it detects any.
Step 3: Purge trapped air with a pressure reducer valve
This may not be applicable for many hot water systems because most of today’s hydronic loop systems are too “modern” to allow it. However, you can also drain your hot water system of trapped air using the pressure reducer valve.
The pressure reducer valve is a pressure control valve used to maintain constant reduced pressure in a pipeline where the flow fluctuates. It helps maintain reduced pressure in selected locations of the hydronic system by reducing incoming high-pressure liquids into a constant low pressure to protect the hydronic system.
The primary part of the pressure reducer valve is the main valve, an upward-seating valve with a piston at the top. The valve also comprises an upward-seating auxiliary valve, a controlling diaphragm, and an adjusting spring/screw.
Some hot water systems are designed with the pressure reducer valve and constructed to purge the entire hydronic loop using a water hose. The pressure reducer valve has a fast-fill handle that overrides the pressure reducer. Using this handle, you can give your loop full pressure as supplied by the city or well system. This will purge trapped air throughout the loop.
Just make sure to wait for the hot water system to cool down before you begin the purge to avoid a thermal shock.
Step 4: Call the Pros
Unfortunately, neither the automatic nor pressure release valve is simple for bleeding your baseboard heating system. For instance, the automatic valve may not completely rid your baseboard heating system of trapped air. Depending on the location, you may still have air bubbles along the pipes, even with regular bleeding.
Meanwhile, the pressure release valve approach is too complex for the regular user. Moreover, very few houses are designed with pressure release valves as today’s plumbers are keen on cutting corners to get the work done faster. So, you may not even have it in the first place.
For the above reasons, we strongly recommend that you keep your HVAC technician’s number on hand. If you can’t locate the bleed valve and can’t seem to find the automatic pressure release valve either, consider calling the technician. The same applies if you keep hearing unusual sounds from your baseboard or hot water system, even with the automatic valve operational.
You don’t have to worry about air trapped in your baseboard heater because your baseboard doesn’t have bleed valves. Instead, an automatic valve or pressure release valve allows you to bleed the heater with minimal effort. Better still, you can always call the pros.