Like any busy household in winter, when the heating system malfunctions it throws the household into coldness and chaos. It also means that you spend hours on any given day trying to find an engineer who has the knowledge to fix the problem. In this article, we answer the common query – why is my underfloor heating not working – to help give you peace of mind about common issues you may face with an underfloor heating system.
If you are having issues with your underfloor heating products, then why not check out our range of underfloor heating kits?
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Why is my underfloor heating not working – common issues
Although generally highly reliable, there are many reasons your underfloor heating could be malfunctioning. These problems can include anything from incorrect setup to incompatible external components, such as flooring, or something as simple as trapped air in the pipes. This guide discusses how you can diagnose these issues, fix them and, most importantly, prevent them from occurring in the first place.
Problems with the pipes
Generally, issues with your heating system are often down to the pipes. If your underfloor heating is a wet system, which runs from a boiler, then it could be a blockage or trapped air. Fortunately, these problems can be resolved just as easily as they occurred. You may want to attempt some of these fixes yourself, though if you lack confidence a plumber or heating engineer will be able assist you.
Blockages
Blockages can sometimes occur and create issues within your heating system. There are a few checks you can do to see if this could apply to your system. Check the flue vent that leads to the outside of your home for blockages or other issues. If there are leaves, twigs and other debris in the vent simply clear them out.
During the winter, check the discharge pipe, especially in very cold weather. On a combi-condenser boiler, this can freeze and prevent the boiler from working at the time you need it most. To resolve this, you simply need to melt the ice and treat the area with some antifreeze.
Cold spots where your system is laid could mean there is an internal blockage. This is unlikely to happen but flushing the system could be the answer. Seek the help of a qualified heating engineer if you think this may be your problem.
Trapped Air
Trapped air is the most common problem with a malfunctioning underfloor heating system, especially one that uses hot water flowing through sub-floor pipe work. Air can get caught up in the pipe and stay there, causing issues with the whole system. You will have experienced this in the past with radiators and you will likely know it is a simple problem to address.
You can easily prevent this during installation. Measure include:
- When installing your underfloor heating system, do not fill it from the boiler filling loop. This pushes water in the pipe, but too quickly, and traps air at the same time.
- When you fill your system, ensure the water is flushed through the pipework. Pour it in one end until it starts to flow out through the outlet point. This way you know that there are no air bubbles stuck in the pipe.
If it’s too late for this and the system is already installed, you can remove the trapped air by bleeding the system. Bleeding is the opening of valves to release air, and some water. This will need to be completed at each valve. You can also flush water through the pipes, which will clean the pipes and flush out air at the same time. If you are unsure how to do this, contact your installation team.
Leaks
If the system keeps losing pressure, it suggests there is a leak somewhere. When the pressure drops, top your system up following the manufacturer’s guidelines. If the pressure stays low, go back a step and check that the connecting pipes to the manifold are in place and not leaking. It is rare for underfloor heating pipes to leak and if they do it is likely that the damage was caused during installation. This is both good news and bad news. If the pipes are leaking, then you should have recourse to seek remedy with the installer. The bad news is that it will likely be a substantial job.
Incompatible top layer of flooring
Did you check that your flooring is compatible with your underfloor heating system before you had it installed? Your system could be working fine, but your flooring might be supressing the heat and not allowing it to flow through properly. This needs to be amended as soon as possible. A build-up of heat underground with no release could cause damage to different parts of the system.
- Choose a flooring material with a TOG rating of less than 2.5. Anything thicker or more insulated will not let the heat through. You can purchase carpeting with underfloor heating, but it cannot be too lush.
- Make sure this material that has thermal conductivity. This means it not only grabs heat efficiently, but it also holds on to it for as long as possible. Wood floorings do work with underfloor heating, though you need to research the best type. Stone and tile are the most efficient conductors of heat.
- Research the best floor types for underfloor heating before installing your system. Your heating engineer should be able to offer suitable advice.
Incorrect Setup
If set up isn’t completed properly, you’ll immediately come across problems that may stop your system from working correctly.
Screed
If the screed was laid on the piping work without the pipes being under pressure, or full of water, the screed may have obstructed the piping. This means the hot water may be struggling to find its way through. The screed also needs to be allowed to cure and set without the pipes being heated, even though water should still be running through the system while this happens, it should be cool water.
Unfortunately, there are no easy solutions to incorrectly laid screed. Such problems are a result of an error by workmen. If you hired an engineer for the installation, then you should request they come back and resolve the issue. Latex repairs to crack screed will not resolve your heating issues. It will likely require your piping and scree to be re-laid.
To understand more about screed, follow these guides:
Setting controls correctly
It’s vital for the continued health of your underfloor heating system that you set the controls up correctly. Although no major destruction can happen with a simple slip of the controls, continual running of the underfloor heating with the wrong set-up can cause issues.
You should check the following: –
- Thermostat – are the thermostats working for the rooms they’re set up for? Check the connection between it and the boiler by changing the temperature on the thermostat and seeing if the boiler and heating system responds
- Mixing valve – This should be set at 45c for concrete screed floors and 55c for suspended wooden floors to avoid any issues that can be caused by overheating
Your installer would be pleased to give you a demonstration of how to set the temperature for each room either with the thermostat or the underfloor heating controllers. The major benefit of underfloor heating is the ability to split it into zones. When you are initially shown how to use the heating ask the installer to make sure the zone corresponds with the area that heats up.
Preventing Wet Underfloor Heating Problems
Looking after your heating system means you could potentially spot problems early, avoiding a complete breakdown. Early detection of problems with the underfloor heating could help you prevent the damage from spreading and becoming more serious. In short, continual good maintenance of your underfloor heating will likely prevent anything serious from happening that will stop it from working altogether.
Insulate pipes
When it’s cold outside, water in external pipes can freeze. As the ice in pipes thaws, it expands, and this can lead to split pipes. From water gushing down walls to irritating, hard-to-repair drips, the damage can be expensive to repair.
Insulate all pipes, especially those outside. The pipe insulation tubes available from high street and DIY retailers cost a few pounds but can be the tool that saves you hundreds of pounds in damage to your home and heating system. Your system pipes should be insulated when they are installed – make sure this is a service your installers offer.
Service it
A regular service – once a year if your budget allows – will ensure that everything is as it should be. For example, the correct pressure in the system, a flush through (if needed) and no leaks etc.
Invest in an annual service. Costing a few pounds a month there are many heating engineers and companies who offer an annual service as well as breakdown cover. This is perfect for when there are heating malfunctions. You are right to assume that your underfloor heating is robust and, like your central heating, will be unlikely to fail. However, you will more than likely have your boiler serviced once a year. The same principle should be applied to your underfloor heating.
Mechanical wear and tear
Fortunately, there are very few moving parts in the underfloor heating beneath the floor. The design of the heating system is such that most moving parts are in the boiler, which can be easily accessed for servicing by a technician. As well as regular servicing, keeping an eye out for tell-tale signs of damage e.g. the floor feeling too hot underfoot, or some spots not heating up at all. As soon as you spot a potential problem, call in an engineer.
Noises, clanking and smells
You will likely spot if there is no heat or if there is too much heat. However, your heating system can give off other signs that there are problems that need looking at.
- Noise – underfloor heating is a silent system. There shouldn’t be any gurgling, banging, clicking or any other kind of noises. If you start to notice it seems noisier than what it should be, there could be a problem although most are easily solved. Hearing the water run through the pipes could suggest there is an obstruction or air, which can be resolved with a flush through of the system and/ or bleeding of each valve.
- Boiler noises – boilers can make clinking sounds etc. because they are the mechanical part of the system. Again, you are familiar with the operational sounds of your boiler, and anything out of the ordinary could suggest a problem. You should not attempt to repair a boiler yourself, as you need a registered heating engineer. It can be dangerous to remove the cover of a boiler and begin working with the parts.
- Smells – boilers, underfloor heating or any other kind of heating system should not give off any smells and that includes a gas or fuel smell. If you do smell gas, call the emergency gas number 0800 111 999 and switch off the appliance. Click here for more information on what to do if you smell gas in your home.
Common faults with boilers, such as boiler pressure too high, and heating systems shouldn’t cost the earth to repair but when you present something as an ‘emergency’, you may find that it comes with an ‘emergency’ price tag too. Ensure your heating system is properly maintained to prevent issues presented in this guide.
Summary
There are some essential messages to take from this guide. First, your underfloor heating is robust. It has been designed to withstand years of use, as suppliers and installers understand that rectifying errors beneath your floor is challenging. Feel reassured, it is unlikely that something will go wrong.
It is a good idea to respond to small problems quickly. The resolution of areas of coolness, or areas that are too hot are usually easy to rectify. Regularly flushing through your underfloor heating and making sure external pipes are insulated could prevent many problems occurring.
The boiler, as with radiators and normal central heating, has the most mechanical parts and could, therefore, go wrong. Regular servicing will, in the end, save you money.
Sources
National Gas. (2023) Emergencies and safety advice. [online] Available at: https://www.nationalgas.com/safety-and-emergencies/emergencies-and-safety-advice [accessed 19/07/24]
