Underfloor heating systems can be run using most heating fuels, which means it is an option available to most homes.

Unlike central heating with radiators which mostly heat air that then travels round your home (by convection), underfloor heating transfers heat through both convection and radiation helping to create a comfortable and constant temperature in the room.

Underfloor heating systems come in two types, wet and dry.

‘Wet’ underfloor heating systems

Wet or hydronic systems can be run using a mains gas boiler or a heat pump, with the latter being especially efficient as it produces the lower-temperature heat appropriate for underfloor heating systems. Oil or solid fuel boiler can also be used but the existing boilers should be checked to see if they are compatible with the lower temperatures needed for underfloor heating.

In wet systems, heated watercirculates through reinforced polythene piping, usually with separate circuits for different rooms or areas. Each circuit connects to a control unit called a manifold. This has regulating valves and a thermostat so different rooms can be heated to different temperatures and at different times. A circuit will close when a room reaches the desired temperature and open again when it falls below.

Types of wet underfloor heating

There are three main types of wet underfloor heating, depending on the type of floors that the building has:

1) Solid floors

Solid floors are the common choice for new builds or large refurbishment projects. Here, the underfloor heating is built into concrete or screed floors, making it a permanent feature. Insulation is laid first, with the pipes then put down in a specific pattern before the concrete or screed is poured. Many types of floor finish can be laid over it, including wood, stone, tiles or vinyl (also carpet, though careful consideration is needed to ensure it won’t be affected by the heat or insulate against it).

2) Suspended floors

The heating system is installed by laying the pipes between the joists in the suspended timber floor; it is very important that there is suitable and adequate insulation below otherwise heat could be lost to the space below. Aluminium spreader plates can also be installed with the pipes to help distribute the heat more evenly. A tongue and groove floorboard casing is then installed that allows a range of floor coverings to be fitted on top, with the same considerations as described above.

3) Floating floors

Floating floor is the quickest type of underfloor heating to install. It can be used above an existing solid or wooden floor, making it ideal for renovation. Here the pipes are inserted into preformed heat plates that rest in grooves in the insulation. As the system is fitted on top of your floor, be aware that this can significantly raise the floor level.

‘Dry’ underfloor heating systems

Dry underfloor heating uses electric wires that heat up when electricity is switched on. The system will either come as ready-made mats or lose wires that need to be fitted. Dry underfloor heating should be connected to individual room thermostats so that each room or area has its own temperature.

Electric underfloor heating is often preferable for existing builds as it’s easier to install than water pipes and can also fit more awkward spaces. It’s also likely to be more responsive than wet systems so a room will warm up quicker. But, electricity is considerably more expensive as a heating fuel than gas, so it’s likely that these systems will be more expensive to run.

Cost of underfloor heating

Installation costs for underfloor heating vary greatly, depending on the type of system installed, the size of the room(s) or area to be heated, whether the system is for a new-build home, extension or an older building, and what kind of flooring you have.

The ‘dry’ electric underfloor heating system is cheaper to install with costs estimated to be between £60-85 per square metre. This type of system is an option for a skilled DIY-er, which would help keep costs down, but a qualified electrician would need to connect it to the mains electricity. Although these systems are cheaper to install, they are generally more expensive to run.

The cost of installing a ‘wet’ system is between £90-110 per square metre, and there could be extra labour costs on top of this as it is more complicated to install. It’s a good idea to speak to an engineer to help you decide whether the work and cost of the system will make it suitable for your home. Although more expensive to install, these systems tend to have lower running costs.

All information on costs has been taken from Checkatrade.

Underfloor heating pros and cons

The chief advantage of underfloor heating is that it feels comfortable. This is because the larger surface area distributes heat evenly around the room.

Another advantage is that because of the large surface area your central heating can run at a lower temperature, saving you money.

Underfloor heating in wet systems generally takes much longer to heat up and cool down than traditional radiators. This is partly due to screed or concrete in which most underfloor systems are embedded. In addition, the water in wet underfloor systems is cooler than the water in radiators because the heat is spread over a larger surface area, so it takes longer to warm up.

Insulation is critical

For the system to provide adequate heat and be cost-effective, it is critical to ensure your property is well insulated and draught-proofed. This will minimise heat loss and reduce the heating up time.

Due to the lag time described above, underfloor heating is best left on a low temperature for a longer period of time and is generally more suited to homes where people are in most of the day. If it is only used in the morning and evening an underfloor heating system alone may not provide sufficient warmth.

If the underfloor heating is covered by surfaces such as timber or vinyl which react quicker to changes in temperature, then this may be a solution. But the running cost is likely to be higher, as you don’t have the advantage of a heat store to help retain and balance the room temperature.

Underfloor heating is expensive and disruptive to retrofit. It’s usually only a good option if you are already undertaking significant building work.

Running costs will vary considerably, depending on what fuel you are using to heat the system, what kind of floor covering is used and how well insulated the home is. Electricity will be the most expensive, but there are ways to bring the running costs down if you consider renewables.

How renewable energy works with underfloor heating

Wet underfloor heating

Air or ground source heat pumps are particularly effective when used with wet underfloor heating. That’s because heat pumps are also designed to be left on for on for longer periods of time and to operate at lower temperatures. Heat pumps still need some electricity to run – you could generate that electricity via solar panels.

Dry underfloor heating

Solar panels could also be used to power a ‘dry’ electric underfloor heating system.

Using batteries with solar panels

If you have solar panels, using of a battery to store any excess solar electricity would make this even more efficient as you would be able to power the heat pump or electric underfloor heating system when electricity is not being generated, e.g. in the evening.