Underfloor Heating: How it Works

Underfloor heating, in one form or another, has been around for hundreds of years, but has seen a resurgence in popularity in the past decade with the introduction of more efficient heat sources that require lower running temperatures to operate efficiently, like condensing boilers, heat pumps and solar thermal.

Basic principles

An underfloor heating system heats a room's floor structure, which in turn warms the room itself. This is achieved in a "wet" underfloor heating system by passing heated water through plastic or composite pipes which are installed in the floor. Various installation options are availble to suit different floor constructions. The underfloor heating pipes are routed back to a central manifold, typically one per floor, which is used to distribute heat to the relevant loops as and when required.

Comfort and efficiency

Underfloor heating vs. radiators - temperature gradient comparison

Underfloor heating produces a more gentle, even heat than a radiator or blown-air system, with the main component of heat output being infrared heat radiation, rather than convection. This affords comfort at lower room temperatures as the reduced convection results in fewer draughts.

The larger heating area provided by using an entire floor, rather than a relatively small radiator panel, also allows underfloor heating to operate effectively at much lower running temperatures than a traditional radiator heating system.

All of these efficiency improvements mean that a correctly designed underfloor heating system can provide annual fuel savings of up to 25% over a traditional radiator system.

Temperature control

Typically, an underfloor heating system is divided into control "zones" consisting of individual rooms (i.e. bedroom) or groups of rooms with similar heat loss and use characteristics (i.e. kitchen and utility), with each zone being controlled by its own room thermostat.

For more information on our range of room controls for underfloor heating, visit our Control Options page.

Project suitability

Underfloor heating is ideal for a modern, well insulated property, but care needs to be taken when using the system as a replacement in older properties in which the insulation is not being improved. Properties with single glazing and/or without an insulated cavity wall will need to be brought up to modern building insulation levels (i.e. at least Part L 2002), before underfloor heating can be considered as an efficient, sole heating solution for the property.

It is also important to note that underfloor heating is designed to operate at a more constant temperature than a radiator system, typically rooms are maintained at 18°C when not occupied and are brought up to 21-22°C when in use. If the underfloor heating system is used only for short, infrequent periods of a few hours a day without a setback temperature being maintained, then other, faster-response systems such as radiators may provide lower overall running costs.

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