How Underfloor Heating Works

How underfloor heating works

In its simplest terms, underfloor heating is a method of warming a room or entire building by using the floor as a radiator.

Water and electric underfloor heating

There are two types of underfloor heating, water and electric. Warm water systems (‘wet systems’) work by pumping water through pipes installed under the floor. Electric systems (‘dry systems’) use electric wires or cables placed underneath the floor, which act as heating elements.

Both systems work on the principle that heat rises, meaning warmth from under the floor is pushed upwards into the room rather than remaining in a localised area.

The floor is heated to a lower temperature than with conventional radiators. This is because the floor offers a much larger surface area than a radiator, so underfloor heating doesn’t need to run at such a high temperature – saving energy and money.

Circuits and thermostats

When we install an underfloor heating system, each room or area will have its own circuit. We can also provide individual thermostats for each room, so you can heat them to different temperatures depending on how often they’re used.

When the room reaches its pre-set temperature, the thermostat sends a signal to an electrically-operated valve, closing that circuit. The floor effectively becomes one large heat store that gives off a gentle, even and radiant heat to the whole room.

Heat sources

Warm water systems can be used with any type of boiler, making them ideal for retrofit installations. However, you’ll maximise your energy savings with a modern condensing boiler, or by fitting an air or ground source heat pump.

Electric underfloor heating can be powered by solar PV panels, reducing your electricity costs. Both solar PV and heat pumps offer the added benefits of government-funded grant schemes.

Things to consider

As with any type of heating system, underfloor does have some potential drawbacks that can affect its efficiency. Please consider the following points before going ahead with your project.

  1. If you want to lay carpets over your heating system, please note that natural fibre carpets give a better performance than man-made fibres.
  2. Choose crumb rubber-based underlay rather than the closed cell foam type, as this is an insulator.
  3. Underfloor heating can take longer to warm up than radiators. This means it’s not practical to have it switched on for very short periods. Ideally, you should programme your system to run for 4 to 12 hours a day. This may seem a lot, but once the fabric of the building has heated up, your system won’t need much energy to maintain the required temperature. Note that your system will heat up more quickly if your floor covering is a good conductor, e.g. stone or tile. Underfloor heating fitted under carpet will take longer to warm up.
  4. As with any other type of pipe, it’s possible to put a nail through a water underfloor heating system pipe and cause a leak. However, the multi-layer pipes we use are made from metal as well as plastic, so you can use a metal detector to locate them.
  5. If your underfloor heating pipes are buried within screed, you’ll need to put at least 35mm of screed above the pipes to protect them and make sure the surface is flat. With timber floors, the pipes will be right underneath the planks, so you’ll need to be very careful. However, in the unlikely event that a continuous length of pipe is damaged, you just need to fit a simple connection piece to make a permanent repair.
  6. Underfloor heating systems require very little maintenance.