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Bleed underfloor heating is a process that is carried out to remove trapped air inside the floor heating system. Trapped air can cause problems in the circulation of hot water. When air is trapped, hot water cannot flow properly through the pipes, This causes some areas to be colder than others. In other words, there is uneven heating and decreased efficiency.
If left unchecked, trapped air can even cause damage to heating system components. By bleeding regularly, not only can hot water flow efficiently throughout the system. But it can also extend the life of the system and reduce the possibility of damage.
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How to Bleed Underfloor Heating
Bleeding underfloor heating is an important step to ensure that the heating system is functioning properly. Here are the steps you can follow to do this process correctly.
Prepare the Necessary Tools
Prepare a container to collect water and a radiator bleed key if needed. In addition, towels or rags to clean up spills
Turn off the Heating System
Before starting the bleeding process, make sure to turn off the heating system. Also, let the water in the pipes cool. This is important to avoid the risk of burning yourself when handling the bleed valve.
Locate the Bleed Valve
The bleed valve is usually located at the highest point of the heating system. If you have multiple loops or zones, be sure to locate and check each valve. However, many modern underfloor heating systems (especially those with a manifold) do not use a single bleed valve. Instead, air is released through manual or automatic air vents located on the manifold. If your system has a manifold, make sure to check the air vents on each loop.
Open the Bleed Valve
Use the bleed key to carefully open the valve. Do this slowly to avoid spraying water. You will hear a hissing sound as the air escapes. Have a container ready to catch any water that may escape.
In manifold-based systems, bleeding is done loop by loop. Close all loops except one, bleed that loop until the water flows steadily, then close it and move to the next loop. This method ensures that air is fully removed from each zone.
Wait for the Water to Flow Steadily
After a few moments, when the air has escaped, the water will begin to flow steadily. Wait for the water to flow steadily without air bubbles. This indicates that the bleeding process is complete in that section. Immediately close the bleed valve tightly. Make sure there are no leaks after closing the valve.
Check the System Pressure
Once finished, check the pressure in the heating system. If the pressure is too low, add water to the system as needed. The goal is to maintain performance.
Restart the Heating System
Restart the heating system and check for any changes in heating performance. Note that the previously cold areas should now feel warmer.
When to Bleed?
Regular bleeding is recommended, especially if you notice the following signs.
Noisy System Sounds
If you hear a hissing, rumbling, or other loud noise coming from your heating system, this could be an indication of trapped air in the pipes. This sound usually occurs when water is moving through a line that is blocked by air.
Cold Spots
Bleeding is necessary when certain areas of the floor feel colder than others. Or, if the temperature in the room is uneven. For example, certain areas feel warmer while others remain cold. This indicates that the hot water is not being able to flow properly to those areas because of trapped air.
Unstable System Pressure
If you frequently check your system pressure and find that it is too low, this could be a sign of a leak or trapped air. A system that is not getting enough water can affect the efficiency of your heater.
Warm and Cold Pipes or Valves
If you touch a pipe or valve in your heating system and feel a significant difference in temperature, this could indicate that there is trapped air. Pipes that should be hot but feel cold indicate that the water flow is blocked. However, pipes under the floor cannot be checked directly, so the manifold is the best place for you to detect temperature differences.
Common Mistakes When Bleeding Underfloor Heating
Understanding common mistakes that can occur when bleeding is essential to ensure the process runs smoothly and effectively. Here are some common mistakes.
Not Turning Off the Heating System First
One of the most common mistakes is not turning off the heating system before starting the bleeding process. This can cause a risk of burning if hot water comes out of the bleed valve.
Ignoring the Use of a Container
Some people often forget to prepare a container to collect water that may come out when opening the bleed valve. Hot water can cause damage to the floor or surrounding equipment.
Not Checking System Pressure After Bleeding
After the bleeding process, it is important to check the pressure in the system. Ignoring this can cause the system to perform less than optimally. Also, it requires adding water to the system. Most underfloor heating systems operate at around 1.0–1.5 bar. Keeping the pressure within this range helps maintain efficient system performance.
Opening the Bleed Valve Too Much
Opening the bleed valve too wide or for too long can cause excessive water to flow out. This can result in unnecessary water loss and decreased pressure in the system.
Not Checking All Loops
If your heating system has multiple loops, often only one loop is checked. Neglecting the other loops can lead to undetected heating problems.
Using the Wrong Tool
Using the wrong tool, such as a wrench that doesn’t fit the bleed valve, can damage the valve. Be sure to use the right tool to avoid damage.
Ignoring Other Signs of Problems
Sometimes, trapped air isn’t the only cause of a heating problem. Ignoring signs like leaks or strange noises can lead to more serious problems down the road.
Final Note
So, do you understand how to bleed underfloor heating? By following the steps above, you can ensure that your heating system is working properly. Be sure to perform regular checks to maintain system performance!
To complement this guide, we’ve included a third-party video that shows the bleeding process in action. While it’s not our content, it offers a practical visual tutorial that many homeowners find helpful.