What is underfloor heating?
Underfloor heating is a way of warming a room by heating the floor space. It’s actually a system that’s been around for thousands of years – the Romans built raised floors and had a continuously burning fire in one corner of the room, so the hot air could circulate under the floors and warm the room.
Nowadays, the theory’s the same but with much more efficient technology. There are two modern types of underfloor heating:
Electric Underfloor Heating (Dry System)
This is a series of electric wires installed beneath or within the floor finish. The wires can be loose-fit, modular or as a heating mat. Electric systems are cheaper to buy and have installed but are more expensive to run than water systems. They are generally better suited to smaller rooms, such as bathrooms.
Water Underfloor Heating (Wet System)
This is a series of looped pipes, connected to a boiler that circulates warm water through the floor. Water systems are cheaper to run than electric systems but they are more expensive to have installed and require more space so existing floor levels may need to be raised. Water systems can also be used to provide cooling.
The type and design of the installation you need will depend on; the size and dimensions of the area that needs heating, the type of insulation in the building, the existing floor structure and the choice of flooring.
How much does it cost to have underfloor heating installed?
A typical electric system will cost between £10,000 and £12,000 for materials and installation. A typical water system installed in the same area will cost between £12,000 and £15,000.
Preparation: Break out the existing floor
Layer 1: The bottom layer – usually simple concrete
Layer 2: The insulation – minimises downwards heat and forces heat upwards
Layer 3: Floor heating pipes/electric heating cable – Budget from £75 per square metre for electric or £100 per square metre for water systems
Layer 4: The screed – a thin layer of sand cement mixture poured on top of the heating pipes, giving you a smooth, level surface to lay your flooring materials on top
Additional: Controls – £80 to £150 per room
What are the running costs?
The running costs for each system will vary depending on; the size and shape of the room, how well insulated the room is, what the structure below the heating system is like and the choice of flooring.
Electric underfloor heating systems vary in wattage from around 100W to 200W per square metre and cost an average of 12 pence per kWh.
The running costs of water heating systems are much more variable but the system will work at 20-40°C less than your radiator system so you could see savings of up to 50% on your current bill.
Will I need a new boiler/consumer unit?
Not necessarily – water underfloor heating systems will work with any type of boiler but you might need to check that an older boiler will be able to cope with the extra demand. Electric underfloor heating systems just need to be connected to your mains supply.
What difference do different floor types make?
Most types of flooring are fine to use on top of underfloor heating but some materials are better than others
Stone/Ceramic – warms quickly and stays warm for longer
Concrete – takes longer to warm up but stays warm for longer
Wood – real wood can warp and shrink if the wood contains a lot of moisture. Engineered wood or laminate are a better choice to keep the look of wood but should be less than 18mm thick to allow the heat through
Carpet – takes a long time for the heat to get through. If using, keep the combined tog value of the underlay and carpet below 2.5
Depending on your choice of flooring, your underfloor heating installer should be able to adjust the output, underlay and type of screed to suit the floor type
Does underfloor heating require maintenance?
Water systems can potentially develop air locks (in the same way that radiators can) which can reduce the amount of heat the system generates and the system may need bleeding occasionally.
What happens if there’s a problem?
Being covered in a layer of screed and flooring, underfloor heating isn’t the easiest system to repair. Water systems are more difficult to repair than electric systems but there are tools available, such as thermal imaging or ground microphones to pinpoint the location of a leak. For electric systems, an electrician can also use various pieces of equipment to identify the site of the failure and then fix the break using a repair kit.
If you have any questions about installing underfloor heating in your home, or just about creating your dream home in general, go ahead and book a free call below with Yoop.
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