What is a heated floor?

The heated floor is an underfloor heating system, offering optimal comfort of use. It can be operated by a boiler or a heat pump. Integrated into the floor of your home, it heats all the rooms evenly.

The principle of operation of the heated floor

Underfloor heating is a device for heating a building at low temperatures. The floor surface is used to heat the indoor air, which produces an optimal result both in terms of thermal and acoustic comfort, as well as visually since the emitters remain invisible. Indoor air quality is also improved: there is no movement of dust.

The operating principle of a heated floor consists in heating a large surface rather than several small surfaces very warmly, as do hot water radiators for example, while delivering the same number of calories.

It is a “distributed” heat emitter. This differs from the traditional radiator which is a “localized” emitter.

The heated floor ensures the diffusion of heat by conduction and the heat can be produced by:

• Electrical resistances are distributed in the mass of the concrete screed (when it is an electric heated floor)
• The circulation of hot water in pipes irrigated in the screed

Temperature regulation

The floor distributes heat evenly in all rooms of the house. The whole surface of the floor acts as a large radiator and diffuses the heat by radiation throughout the dwelling.

It is also possible to regulate the temperature of the heated floor by connecting it to a room thermostat, wired or electronic. Placed in each room of the house, the thermostat makes it possible to save money and to set different temperatures in all the rooms. It is then possible to program the thermostat on a daily basis, or on a weekly basis.

The Legrand brand, through its Céliane and Mosaïc ranges, offers wired or battery-operated room thermostats, perfectly suited to underfloor heating. The user can regulate the temperature in a building efficiently and optimally, for 100% personalized comfort.

The different underfloor heating technologies

There are different technologies that make it possible to operate a heated floor

Low-temperature water underfloor heating

Water is the emission agent for heat or cooling. It circulates through a network of tubes installed in insulating panels and covered with a screed. This type of heating is then powered by an energy production system according to the free choice of the consumer. It is in fact compatible with all types of energy: natural gas, electricity, heat pumps, solar, etc.

The system, integrated with a floating slab, consists of  :

• Thermo-acoustic insulation
• Tubes made of synthetic materials
• Control manifolds for temperature regulation and comfort
• A floating concrete slab or a cement mortar or an anhydrite-based screed

It is possible to install this type of underfloor heating in all types of construction, new or under renovation, even the heaviest.

Electric radiant floor

It is an electric floor heating system, regulated room by room. It consists of a heating element (an electrical cable packaged in preformed frames) incorporated into a floating screed, or simply placed on it if its thickness is between 4 and 5 cm. The screed is itself placed on a thermal insulator, to direct the flow of heat towards the part to be heated.

This device is generally installed as part of a new construction or a major renovation involving the demolition and complete repair of the floor. This type of underfloor heating keeps the heat in longer. The floor is constantly tempered, regardless of the coating chosen.

The thermal fluid floor heating

The heated floor can be powered by heat transfer fluids, and coupled with a heat pump.

How to install and maintain underfloor heating?

To install an electric heated floor, 5 steps are to follow  :

• Install underfloor heating insulation (peripheral strips and floor plates)
• Install a heating cable in a coil or on a grid
• Install the power supply
• Set up underfloor heating regulation (connection to the control device, checks before covering)
• Switch on underfloor heating

To install underfloor heating, the surface of the floor must be stable, smooth, and level. It is also necessary to carry out a screed of average which is obligatory to pass water and electricity conduits, with horizontal.

Before covering the electric underfloor heating, it is advisable to carry out a general check of the insulation of the wiring and of the continuity of the conductive cores, and of the shielding braid. This control is carried out during the pouring of the coating screed.

There are 3 processes for making a heated floor screed  :

• The cover concrete
• The fluid screed
• The sealing mortar
• The difference can be seen in the thickness of the screed

To lay a water-based heated floor, the support must also be clean and flat, without plaster deposits or other defects. If the installation of the water heating floor is done as part of a renovation, it is important to:

• Put in place partitions and frames
• Build the structures (such as the chimney for example)
• Have installed the sanitary water and electricity pipes beforehand, in compliance with the standards in force

Once these manipulations have been carried out, all that remains is to lay the heated floor

• Installation of the manifold block
• Insulation of the water-heated floor
• Pipe laying
• Connection of circuits, filling, and pressure test

Underfloor heating maintenance

An electric heated floor does not require any particular maintenance.

If you have installed a water circulation floor, it is best to have it monitored regularly. It is recommended to carry out intervention by anti-mud treatment during a purge, or a maintenance intervention on the heat generator (whether it is a boiler or a heat pump).

The heated floor is maintained, just like the hydraulic radiators. Flushing should be done approximately every 5 or 7 years as sludge can form which, as it hardens, can completely clog the tube.

Which floor covering to choose with underfloor heating?

The choice of a floor covering is an essential criterion in the installation of a heated floor, even if it can work regardless of this covering. The difference? Heating comfort and installation performance differ.
That said, several types of flooring can be used:

• The carpet

  It is necessary to choose a thin model, preferably needled, so as not to suffocate the heat. Likewise, thick rugs are not recommended.

• wooden floors

  Among the existing wood species, the most suitable for underfloor heating are oak, teak, or fir. Maple or beech are not recommended as they tend to warp due to heat. For this same reason, favor narrow blades over wider blades.

• The floating floor

  It is not inadvisable, but it is recommended to take care of the possible presence of an air gap between the floating floor and the screen. This interstice can prevent the diffusion of heat on the surface.

• Reversible floors

  They allow you to heat or cool your interior. So they are possible.

Tiles and natural stones

These are the most suitable coatings for underfloor heating, as they conduct heat well. It is possible to choose porcelain stoneware tiles, extruded stoneware, or terracotta. Other coatings such as limestone paving, marble, and schist are also very suitable. Reconstituted stone, enamels, and glass paste also conduct the heat of a heated floor. It is nevertheless advisable to avoid very thick pavings in natural or reconstituted stone, because of the thermal inertia which is too strong. The maximum recommended thickness is 20 mm.

Most floor coverings are compatible with underfloor heating, whether electric or hydraulic; but it must be taken into account that the less insulating the material, the better the heating capacity of the floor.

The heated floor has many advantages: thermal, economical, ecological, and allows the diffusion of soft and harmonious heat.