Installing Electric Underfloor Heating On An Existing Tiled Floor

Electric underfloor heating has much to commend it. It is clean, quiet in operation, requires no maintenance and is 100% efficient at the point of use.

By avoiding central heating pipes and radiators, you have more flexibility about the placing of furniture and fittings within a room. Further, allergy sufferers will benefit from the near absence of air circulation, dust and dryness associated with traditional systems.

There’s nothing quite like radiant heating which is what electric underfloor heating is. It is the most efficient means of heat delivery in existence and it provides greater comfort than any other heating system.

Radiant heating is a low temperature system that in most cases can provide energy savings of 20-40% over alternative types such as ducted warm air, oil or gas fired traditional radiator heating systems.

Instead of heating air, radiant heating warms people and objects directly so the thermostat can be set 2 or 3 degrees lower. The fully programmable digital electronic thermostat has been developed specifically to enable these energy savings to be achieved on a room by room basis with optimal comfort.

Radiant floor heating delivers personal comfort by controlling the radiation loss from the body. If the surrounding surfaces, (warmed by radiant heat), are roughly the same temperature as our body surface, we feel comfortable with a good sense of well being.

Electric underfloor heating from a reputable manufacturer can be installed in any room including bathrooms, wet rooms, kitchens and conservatories. However, there are different systems to suit different floor materials and coverings and the purpose of this article is to give you the best advice for which system you need.

Tiling Over An Existing Tiled Floor

First of all, we will look at what you need for providing a system where a ceramic tiled floor exists. There’s no need to remove existing ceramic floor tiles – you can install heating mats directly on top of the existing tiles and then tile over them as normal. This type of heating mat is ideally suited to installation within the adhesive layer – the method preferred by professional floor tilers. There is normally no need to reduce door heights or raise skirting boards when you install a heat mat in this way. However, to maximise the effectiveness of your heating, we recommend that you install Thermal Insulation boards below the mat which may necessitate making alterations to any internally opening doors.

To determine which size of heating mat you need from the range, you need to measure the room(s) in question. Here is a guide as to how to measure the area:

  • Measure the room, excluding all permanent fixtures and furniture.
  • Allow a 10cm unheated border all around the outside of the room.
  • For an area that is not a square or rectangle, the easiest method is to divide the room into rectangles and measure each one; calculate how many square metres each rectangle is and then add them altogether for the total area. Select the mat that is the next smallest to the total area measured. In other words, if the total area to be heated is 5.2m2 choose a 5.0m2 mat.

You also need to choose which level of heating you require from the mats. You will see that as well as different sizes, there are three different choices of heat output – 100W/m2, 150W/m2 and 200W/m2. The 100W is not really suited to ceramic tile situations. The 150W is best suited if the underfloor heating is a secondary system being used alongside some other form of heating. If the underfloor system is the only method of heating, select 200W mats.

When you come to install the mats, you will need to cut the matting itself in order to turn corners etc. but you must never cut the heating cable which should be continuous around the room. You also need to purchase a suitable thermostat and install it and connect the sheathed 3 metre long ‘cold tail’ to it. Select a position around 1.5m from the floor which is out of direct sunlight and any excessive draughts. If you are installing these mats in a wet room, you will need to add a waterproof membrane and if in doubt, please contact the manufacturer of the mats.

As an alternative for a replacement ceramic tile floor, you could choose from a range of Cable Kits. These are supplied complete with the cable, a thermostat, conduit for the floor sensor, PVA Primer, a paint roller to apply the primer and strong adhesive tape. Again, I recommend the use of Thermal Insulation before you lay the cables otherwise you waste energy by heating the sub-floor..

This system is more versatile because you can choose a cable spacing to provide the appropriate power rating and they suit rooms with irregular floor areas where a heating mat might be awkward to lay. Think about it as an alternative in bathrooms or kitchens where there may be lots of smaller areas to accommodate because of the fixtures in the room.

Either system can be installed by any competent person following the detailed instructions supplied but the final connection to the mains must be done by a fully qualified electrician under the requirements of the Building Regulations.

For information on Commercial tilers in London click here.