All your technical underfloor heating questions answered!

Amber Underfloor Heating’s Technical Manager, Steven Burnett, answers the most asked technical questions about electric underfloor heating.

1. System Selection & Compatibility

What type of electric underfloor heating system is best for my property?

Typically, it depends on your floor type and installation method.

Heating mats are best for large, regular-shaped areas and are easy to install under tiles and stone. Loose wire systems are ideal for irregular-shaped rooms as they allow for flexible spacing. Foil systems are designed for floating floors like laminate or engineered wood.

Can electric underfloor heating be installed under any floor covering?

Most floor coverings are compatible with electric underfloor heating, but heat transfer varies.

The best options tend to be tiles or stone as they have a low thermal resistance and will allow most of the heat through.  Engineered wood, vinyl, laminate and carpet are suitable, but they are more thermally resistive or have temperature restrictions to avoid damage so need to be more considered.

Solid wood is not always ideal due to expansion or contraction from heat, so always check manufacturer guidelines.

Is electric underfloor heating suitable as a primary heat source?

It can be, depending on the heat output (W/m²) of the system, the room’s insulation levels (well-insulated homes may not need extra heating) and heat loss calculations.

If heat loss is greater than the underfloor heating output, additional heating such as radiators or towel rails may be needed.

2. Installation & Setup

How do I install heating mats or loose wires correctly?

First, lay the mat or wire evenly, ensuring there are no overlaps. Then, keep at least 50mm between cables.  Ensure uniform spacing to avoid any hot spots.

Secure the mat or cable with self-adhesive backing or fixing tape, then install a floor sensor in a conduit for easy replacement.

Performing resistance tests before and after laying the final floor covering are essential.

Do I need insulation boards, and which type is best?

Yes, insulation boards help improve efficiency by reducing downwards heat loss and reducing warm up times by maximising the output into the room rather than down into the subfloor.

Use cement-coated insulation boards for all floor finishes underneath mats or cables.

Can I cut the heating mat if it doesn’t fit my space?

No! You must never cut the heating cables inside the mat. However, you can cut and reposition the mesh backing to fit the layout.

3. Troubleshooting & Performance Issues

My underfloor heating is not heating up – what could be wrong?

There are a number of things to check:

• Is the thermostat correctly wired and switched on?
• Is the heating system receiving power? Check the fuse box.
• Have you tested the floor sensor resistance? Compare readings to manufacturer’s values.
• Is the RCD tripping? There could be a cable fault or damaged wire.

Why is my electric underfloor heating tripping the RCD?

A short circuit may have occurred during installation, or moisture or a faulty connection might be triggering the safety system. Additionally, a damaged heating cable might be leaking current.

How can I check if my heating cable is damaged?

Use a multimeter to check the resistance of the heating element, then compare the readings with manufacturer specifications.

If the resistance is outside the expected range, there may be a break or fault in the cable.

If the resistance of the cable is as expected but the RCD is tripping, an electrician will be required to perform an Insulation Resistance Test on the heating cable at 500V to test for earth leakage.

4. Efficiency

Should I keep underfloor heating on constantly or use a timer?

This is down to personal preference. 

If you turn off the heating completely when it’s not required, the floor and room can cool down a lot, then take longer to warm back up to temperature on the next heating period.

If you reduce the temperature by a few degrees when the heating is not needed, the room and floor will not cool down so much. However, this will cause the heating to come on outside of heating periods.

Can I control underfloor heating remotely with a smart thermostat?

Yes!

Many modern underfloor heating systems support Wi-Fi-enabled smart thermostats that allow remote control via mobile apps, voice assistants (such as Alexa or Google Home) and integration with home automation systems.

5. Maintenance & Repairs

Does electric underfloor heating require regular maintenance?

No, electric underfloor heating is virtually maintenance-free. However, it’s good practice to periodically check the thermostat and floor sensor and avoid damaging floor coverings that could impact the heating cables.

What should I do if my floor sensor stops working?

If the sensor is in a conduit, it can be easily replaced. If it’s embedded in the floor, use the thermostat’s built-in air temperature mode instead.

For further electric underfloor heating support and advice, get in touch today.