Underfloor Heating: Everything You Need to Know

A complete guide to choosing, fitting, and using underfloor heating in your home.

sunny floor

Underfloor heating is one of the oldest forms of heating in the world, but it has made something of a comeback in recent decades and now holds its place as one of our most efficient and cost-effective ways of warming our homes.

Why choose Underfloor Heating?

Underfloor Heating, which is often abbreviated to UFH, is one of the most efficient forms of heating we have available to us today and can offer many significant benefits.

Heat Quality

Radiators have been very popular for a long time, and they do provide some of the warmth we require. However, because of the way in which radiators emit their heat they are not able to provide the quality of heating that UFH is able to give. Underfloor heating emits heat upwards, warming the floor and the contents of the room above in an even fashion, allowing the air to cool closer to the ceiling and therefore wasting little energy. When using a radiator, the warmth emitted from the wall collects beneath the ceiling and escapes through it, and the floors are left cold, meaning that a lot of the energy used to generate the heat is wasted.

Cost

Due to the efficiency of underfloor heating systems, they are highly cost-effective to run, although questions are often asked in regards to their cost-effectiveness. When compared to a radiator system, the benefits are quite clear.

A great way of keeping costs even lower is to combine your heating system with a renewable energy source. This means reducing CO2 emissions and lowering your bills whilst making you and your home a lot more self-sufficient.

Underfloor heating can be combined with:

Biomass Boilers: These use bio fuels such as logs, wood chips, or pellets, to generate heat which in turn can be used to warm water for the underfloor heating system.

Combined Heat and Power Plants: These use the heat generated as a by-product of electricity generation to heat the home, and can improve efficiency by 50%.

Heat Pumps: These pieces of equipment absorb energy and use it to heat the water needed for the underfloor heating system. There are air-to-water heat pumps (taking heat from the air and transferring it to water), water-to-water heat pumps (transferring heat from one body of water to another), and ground-source heat pumps (taking heat from the ground and transferring it to the water in the tubes), and there are plenty of benefits to using a heat pump with UFH.

Solar Collectors: Solar panels collect energy from the sun, and you can use solar panels to heat water for your UFH.

If you are on a tight budget, find out how to choose and run a really cheap underfloor heating system.

Hygiene and Safety

Because the heat comes through the floor, tiled coverings dry quicker and dust mites are unable to survive in carpets. Allergies are also less likely to be suffered in the warm, damp-free environments which UFH creates, making your home safer to live in too.

Before going ahead, make sure you have a good understanding of all of the pros and cons of underfloor heating.

Types of Underfloor Heating

Deciding that you would like to use underfloor heating to heat your home is only the first of a number of important decisions you will have to make. There are different kinds of underfloor heating systems, and different ways of supplying the energy they require. To start with, you will want to decide whether you are going to use a wet or electrical system.

Wet Underfloor Heating Systems

Wet underfloor heating works by pumping warm water through a series of tubes laid beneath the floor inside the home. Generally, this is easier to install in a new build due to the amount of room it requires beneath the floor covering. Retrofitting a wet system is possible, but you may find it is necessary to raise floor levels to accommodate for all of the pipework. In the long run, these systems are cheaper to operate but you may find that installing the system is a little more costly than the installation of a radiator system or electric underfloor heating.

Electric Underfloor Heating Systems

Electric underfloor heating works by warming the floor using an electric current passed through wires or electrical mats laid beneath the floor’s surface. These kinds of system are much easier to retrofit due to their much thinner design, and installation is usually much quicker, easier, and cheaper than the installation of a wet system. However, electric UFH can be more costly in the long term as running costs are greater than those of wet UFH. This is simply because it relies on electricity to perform its function. This greater cost can be combated by combining electric UFH with solar PV.

It is up to you to decide which is best for you: Electric vs Wet?

Combined Systems

Some installers will suggest that underfloor heating should only be fitted in the ground floor of the home, and that it is much easier to rely on radiators to continue to provide the heating upstairs. This is what is known as a combined system, where the two technologies run side-by-side to heat the house. However, it is possible to heat an entire home using only underfloor heating, and combined systems may be best avoided as they are not always the best option.

Design and Installation of Underfloor Heating

The most important part of the design of an underfloor heating system is the carrying out of the Heat Loss Calculation. This vital part of the process is used to determine how much heat your home loses through its walls, windows, doors, ceilings, and floors, and how much heat it will therefore require to keep the house at its optimum temperature. If the heat loss calculation is not properly carried out then your system may not be designed with enough power to sufficiently heat the house, thus resulting in having to rely on additional heat sources such as electric fans or radiators.

The installation of underfloor heating can be a big, complicated, and time-consuming job. The best advice is to hire someone with experience to do the job for you, although electric UFH is relatively simple to fit and can be installed by an experienced DIY-er. See what we think about designing and fitting your own underfloor heating system.

Installers

Picking an installer is in itself a big decision, so take your time to make sure you get the right person for the job.

The fitting of underfloor heating must be undertaken with care, as once the system is sealed beneath the floor it will take quite some work to open it up again to put right anything that was done badly in the first place. An underfloor heating system should not need to be maintained much at all post-installation, but problems can occur if the pipes are damaged before they are buried in the floor. This is why testing the system before the floor is laid is so important.

Underfloor heating is surprisingly flexible, and can be installed in all sorts of buildings, from churches to warehouse and schools to homes, but can also even be fitted in caravans.

Be careful when it comes to fitting underfloor heating in kitchens and bathrooms. There is a split of opinion when it comes to installing UFH beneath fixed items such as kitchen units, baths, sinks, and showers, so take a moment to read our guide to the arguments for and against.

If you are purchasing a new home from a developer, it might be worth asking what heating system they intend to install. This is because many developers will prefer to fit radiators due to their relatively low installation cost. Put in your request for underfloor heating before the floors are laid, and you will reap the rewards of lower builds once you have moved in to your new home.

Floor Coverings

One of the major considerations when fitting underfloor heating is what floor covering to use on top of it. The covering you pick can have significant effects on the performance of your UFH, so it is important to consider this point with care.

Laminate and Wood

Laminate or wood floor coverings can look great, and they can be used with underfloor heating. However, you must be sure to pick the right wood or laminate for your system. Picking a wooden floor with too high a water content can result in shrinkage and cracks forming in the floor.

Carpet

Choosing to use carpet with underfloor heating can also result in some issues. If you pick a carpet which has too high a tog rating then it is possible that the heat will not be able to transfer upwards into the room, and there is a chance of condensation forming beneath the floor’s hard surface. Also, make sure that if you are using an underlay beneath the carpet that the combined tog rating of the two is within the recommended perimeters.

Before you choose what to cover your underfloor-heated surface with, find out what we believe are the best flooring types to combine with an underfloor heating system.

Using Underfloor Heating

Heating the Home

Underfloor heating is very efficient, but it can take a little more time to heat your house than radiators. The amount of time it takes for UFH to heat a room is dependent upon a number of factors, including the floor covering you have chosen. Once heated, and with the system switched off, however, the room will remain warm for much longer than it would if using a radiator system. It is possible, also, to set your underfloor heating to warm up before it is needed.

UFH with Combi Boilers

A common concern amongst those who are installing underfloor heating is whether or not they will have to have fitted a new combi boiler, or whether a combi boiler can even be used with UFH at all.

Thankfully, it can, and it also offers some benefits of its own. A combi-boiler-underfloor-heating combination can actually increase the lifespan of a UFH system.

Controls

Controlling your system is the best way to get the very best out of it once it is installed. The control system in itself is fairly complicated and will have to be fitted professionally. Using sensors, the system is able to efficiently regulate itself to provide heat in the right way.

Weather Compensation

Weather compensation controls are used to heat the home when it is cold outside and to keep it cooler when the weather is warm. These can be very useful in keeping energy usage down when it is not needed, thus maintaining your low bills.

Room Controls

Individual room controls for you underfloor heating system may seem excessively expensive and a little unnecessary, but the Building Services Compliance Guide 2010 recommends that each room uses its own controls to limit the heat it receives. These controls can be in the form of individual room stats or sensors to decide for you how much heat to use, and where to use it.

The controls for your system should be carefully planned before installation so as to get the best out of them.

Maintenance

Underfloor heating is a very low-maintenance system. However, you should perform a few small checks now and again just to ensure that your heating is working as best it can be, and to avoid any potential issues which may otherwise arise in future.

Getting the Most out of UFH

In order for any heating system to work as best it can, it is essential that the house it is fitted in is as well-insulated as possible. To insulate your home really well, try fitting double-glazed windows and wall, roof, and, and floor insulation. This will ensure that the heat produced by the underfloor heating is kept within the room and not let out through leaky walls, doors, and windows. Roof insulation is not so important as heat rising from the floor will have cooled by the time it reaches the ceiling. However, the more insulation you have, the more heat you will retain.

Image by Liz West

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