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How To Bleed Underfloor Heating - The Underfloor Heating Store

How To Bleed Underfloor Heating

Underfloor heating is a great way to save on your heating costs but it also offers other benefits too. These include low maintenance costs, energy efficiency, better temperature control, flexibility, extreme comfort, more floor space and it works with all types of floor coverings. Whether your UFH is connected to a combi boiler system or a heat pump system there is one vital task that you need to know and also need to carry out periodically. That’s how to bleed underfloor heating.

In this guide, we take you step by step through the process of bleeding your wet underfloor heating system quickly and safely. Like traditional radiators that are used for heating your rooms, air can become trapped in an underfloor heating system and this must be removed or bled out of the system to allow for effective heat circulation.

When does an underfloor heating system require bleeding?

It should be mentioned that bleeding is not required for some types of underfloor heating such as electric underfloor heating. To know if, or when an underfloor heating system needs bleeding, there are some tell-tale signs to look out for. Air in the system will cause strange noises like hissing, gurgling and bubbling. This is caused by air bubbles as they move along the pipework.

Also, some areas of the floor might be warm while other areas are quite cold. This is because trapped air will stop the hot water from circulating evenly throughout the pipework. In some cases, there might be no heat at all coming from the system. These are all signs that the UFH system could need bleeding. This situation can only occur with water underfloor heating systems.

What to do before bleeding underfloor heating system

The first thing to do before attempting to bleed your underfloor heating system is to check the pressure. If the pressure is low then simply add more water to the system and then test it. Look around to see if you can see any leaks. If all looks okay then next, check that the pump is working. You should be able to hear it when it’s switched on. Finally, check the air bleed valves. Loosening them will tell you if air is in the system. Now before you proceed further ensure you have a towel, a bowl and a radiator key for the job.

How to bleed an underfloor heating system

Once you have established the underfloor heating system requires bleeding, it is best to bleed every port. Start with the lower side of your home and then move onto the pipes on the upper side, ensuring trapped air is released from the highest point. Open the zone actuators and ensure the ball valves are open.

Fully open each zone valve, one at a time, with a radiator key until you can see the threads. Next, bleed the manifold. Put a towel over the valve and place your bowl beneath to catch the water. When each valve has been fully vented, make sure they are fully closed.

What to do after bleeding your underfloor heating system

When you have bled each valve in turn, flush out the top manifold by attaching a hosepipe. Make sure the drain valve is open on the lower manifold. Flush each loop in turn. If the system needs to be topped up with water ensure the drain valve is closed beforehand. Repeat the process for each valve. When the venting is complete, wait a few minutes and then check the pressure. Adjust if necessary.

Maintenance tips for your underfloor heating

If, after bleeding your underfloor heating system as explained, the pressure is still low then seek professional advice as there could be a leak. Here are some other useful tips for maintaining your underfloor heating system.

• Carry out regular visual inspections

Check for leaks around the valves and manifold and for loose connections.

• Check the water pressure

Especially during the winter months when the system is being used more often.

• Check the system is working properly

Check for cold spots around each room. Check temperatures to ensure each area is warming uniformly.

• Check the thermostat

Check the settings are right for your needs. Consider installing a smart thermostat for better temperature control and maximum efficiency.

• Check the floor covering

Keep the floors clean and free from dust to allow for maximum heat transfer. Don’t allow surfaces to become cluttered with objects.

• Check energy usage

Keep a check on the energy you are using. Should there be any sudden and unexpected rises in energy usage then investigate further.


Underfloor heating systems are generally trouble free but problems can occur due to faulty components or leaks, although this is rare. In the event you find a problem that you can’t fix, contact a member of our underfloor heating team for advice.

For further help and support visit our knowledge base support page.

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