What size spur (electrical connection point) is needed?

A 13amp spur is, in most cases, sufficient. But to calculate the exact loading in amps, there is a simple calculation. Take the total area in m² of the heating mat and multiply it by the power rating of the mat, this gives the heating output in watts. To work out the loading, simply divide this amount by the volts. For example, for an 8m2 UFHD 160 watts/m² mat. 8(m²) x 160 watts = 1280(watts) divide by 230(volts) = 5.57 amps.

How many mats can I install on one thermostat?

To calculate the amount of mats you can fit onto one thermostat click here

Running Costs

Basically, a kilowatt of electricity (1000 watts) costs about 7p per hour at peak rate (consult your electricity board for exact prices). Our underfloor heating mats are rated between 120 watts and 200 watts per square metre. Detailed below are calculations based on installation on an un-insulated concrete sub-floor (with insulation or tile backer boards running costs can be cut by as much as 30%).

1m² of 130 watt costs approx. 0.95 of a penny per hour.
1m² of 160 watt costs approx. 1.20 pence per hour.
1m² of 200 watt costs approx. 1.50 pence per hour.

A kitchen using a 5m² UFHD 160 watt on a floor without insulation would cost approximately £6.75 per month to run.

Will it help to have insulation below the heating mat?

If the system is to be used as the sole source of heating it is essential that there is insulation beneath the heating. Insulation will make the property more thermally efficient and the heating more effective. There are tile backer insulation boards available in thicknesses of as little as 10mm, which are ideal for floor insulation in renovation. Also the underfloor heating will be more efficient as a sole source of heating if the windows are double-glazed and there is insulation in the walls/ceiling (as with any other form of heating). Click on the above link to fill out the heat loss calculation form.

How long will it take before the floor is up to temperature?

Depending on the thickness of the tiles, the warm up time is usually between 40 to 60 minutes.

Where do the RCD/Timer/Thermostat go on the circuit?

wiring diagramThe mat is laid and the cold leads are fed into a junction box. It doesn't matter where you physically fix these items, though you may want them to be hidden in a cupboard. If you have a thermostat that reads air temperature, this will need to be in the appropriate room. However, if it is fitted with a floor sensor then this isn't necessary.

What happens if the system goes wrong?

Once the heating is installed and the floor is laid on top, the heating mat cannot malfunction and is covered by our lifetime guarantee. If the fault is diagnosed once the floor is down, it can be traced down to beneath 1 or 2 tiles. We have never had to take up a complete floor.


It is essential that installers use a good quality adhesive with a flexible additive. If installing on a concrete sub-floor a latex compound is ideal. If installing on a wooden sub-floor then we would suggest a flexible tile adhesive as more suitable. Both types of sub-floor would benefit from being primed (particularly important on wooden sub-floors). It is also very important to ensure that the adhesives are allowed to cure naturally before the heating mats are turned on; this normally takes around two weeks.


The Floor Warming Company can offer a comprehensive installation service. However installation of our under floor heating is very easy for any competent DIY or Trades person.

RCDDamage Alarms

The only time your system is at risk is the time between the installation of the underfloor heating and the final floor finish. To minimise this risk you may buy an UFH Alarm that will alert you should anything damage your heating system whilst un-protected. If the alarm does sound during installation you will need to buy a repair simple repair kit.

All electrical work should be carried out by a Part P qualified electrician.