My Underfloor Heating is not working – Why?

The last thing you need this winter is your Underfloor Heating system suddenly not working and you end with a freezing cold house at Christmas time. We detail some of the potential common underfloor heating problems that you might face.

Underfloor Heating Problems

There are many reasons why your underfloor heating could be causing you problems – it could be due to setup, a faulty controller, the flooring or even air that has become trapped in the pipes. Let’s see if we can diagnose the issues and then discover what steps we might take to stop them from ever happening again.

Underfloor Heating Problems

Pipe Issues

Your pipes are usually the first port of call when you discover an issue with your underfloor heating system. If you have a wet underfloor system and its connects to a boiler then the problem could be a blockage of some kind or trapped air. Either take a look yourself but if you are not sure, contact your local installer to get them to come and take a look.

Trapped Air

This is one of the most common problems of a wet UFH (underfloor heating) system is that air gets trapped during the installation or even worse after everything has been installed.

Therefore firstly, during the installation process, you need to ensure you don’t fill it from the boiler loop as it can push the water into the pipes too quickly, often resulting in trapped air. Secondly, you also need to make sure that the water is fully flushed through the pipes. Essentially, be sure it goes in one end and out the other, therefore knowing definitively that there is no trapped air.

If think there is trapped air after installation is complete, then you might need to bleed the system. So, taking each valve one by one, release some air and water to clear the problem. Again, if you are unsure of what to do, give your local plumber or heating engineer a call.


First port of call with a blockage, another common underfloor heating problem, is to check the flue vents that lead to the outside of your home to see if there are any leaves or twigs.

In the winter time, then you also need to take a look at the discharge pipe as it can freeze in very cold weather.



If you discover that your system is losing pressure then there may be a leak somewhere. Check that the connecting pipes to the manifold are all in place and not damaged. Once again, any issues or if you are not sure, get in contact with whomever initially installed your UFH system.

Flooring Problems

Is your flooring interfering with your underfloor heating setup? Your installation may be working as it should, but your flooring might be blocking the heat and not allowing it to to properly flow. Underground heat build up can cause problems to the rest of your system.

  • Always remember to research the most suitable floor types before your system is installed. Ask your heating engineer for advice or give us a call on 0141 459 3141.
  • Ensure the flooring has a TOG value of less than 2.5. If greater than this, it will be too insulated and not allow the heat to flow through efficiently.
  • Make sure whatever material you end up choosing has thermal connectivity. Stone and tile are the best and wood does work well but you need to research the best type to match your system.


Finally, make sure that your thermostat controls are properly setup for each ‘zone’ of your home. While a wrongly configured control won’t damage your system, it won’t run at most efficient either. Also check your mixing valve, concrete screed floors should be set to 45c and 55c for suspended wooden floors.

These are just some of the most common underfloor heating problems that you are likely to experience and we recommend you speak to a heating engineer or even ourselves before starting your project.

Who are we?

VPS Underfloor Heating are able to answer any question you might have in regards your upcoming project or installation and stock a range of top-quality underfloor heating products from some of the most recognised names in the business including: Grundfos, Heatmiser, ProWarm, ESBE and Salus Controls.

Give us a call on 0141 459 3141 to talk to one of the team or choose one of the options below and attach your plans and we’ll get back to you with a breakdown of what you’ll require to get your installation up and running.


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