Electric vs water underfloor heating: installation, efficiency and user reviews compared

If you’re looking for an efficient way of heating your home, with the luxury of a heated floor, underfloor heating is a great choice. 

There are two types of system: electric and water. 

There are several key differences between these systems, particularly in installation and running costs, that make choosing the best system for you very important. 

Read more: our guide to the pros and cons of underfloor heating

Electric vs wet underfloor heating: summary

The below table summaries key difference between electric and water underfloor heating. 

Read below for more information on these differences.

What is underfloor heating?

Electric underfloor heating

Electric underfloor heating consists of a long wire coiled underneath your floor, which is connected to the mains electricity supply. When the system is switched on, the wire gets hot; this then heats your floors and warms the air in the room.

Because electricity is more expensive than gas, electric underfloor heating is quite expensive to run, so it is typically only installed in a single room. 

Water underfloor heating 

In a water-based underfloor heating system, a series of pipes – typically connected to your boiler – circulates warm water under the floor to heat the space. 

This is similar to the way radiators work, which are also full of heated water. 

For a more sustainable option, you can connect your water heating to a solar water-heating system, or an air- or ground-source heat pump. 

Water underfloor heating is very cost-efficient, so it is generally installed in multiple rooms. For example, you might install it in the whole lower ground floor of your home during a renovation. 

Efficiency of water and electric underfloor heating

Electric is less efficient than water underfloor heating in terms of running cost.

Electric systems run at approximately 25-31°C, on average, depending on how warm you set them. It costs a lot to maintain this temperature, because electricity is more expensive per kWh than gas. 

By contrast, water underfloor heating uses water heated by the boiler (or a similar system), which is generally cheaper than electric. It's also usually cheaper than radiators as well, because it covers a much greater area, so the water in the system can be much cooler – as low as 35°C, compared with 55-65°C or higher for radiators. 

However, the efficiency of both water and electric underfloor systems will be determined by factors such as insulation and the flooring you choose in your room. Thicker flooring such as carpet will require the system to run at higher temperatures, as it is harder for heat to get through. 

Installation compared

In general, both electric and water underfloor heating will require you to remove your floor during installation. However, while electric underfloor heating can normally be retrofitted, this is not normally possible with water underfloor heating. 

Retrofitting means the system can be fitted within the subfloor (the base or foundational layer of your floor), without taking up floorboards or digging up the floor of your home. 

Electric underfloor heating is typically installed by adding insulation over the subfloor. Then the wires are laid in position and taped down. A self-levelling compound (such as screed) can also be applied to the top to keep the wiring in place. 

If you are a competent DIYer, you may be able to do these steps yourself. 

However, you will always need a  qualified electrician to connect the system to the electricity supply and install the thermostat.

Water underfloor heating is more complex to install and should be undertaken by a professional who will lay the pipes, normally into the subfloor. The pipes are then connected to a manifold, the heating system and a thermostat. Insulating screed is usually put on top to hold them in place, to insulate the system further and to level out the floor. Some underfloor heating installers don't do this part – you may need to get it done separately by a builder. 

Installation costs

Every year, we purchase data from the Building Cost Information Service (BCIS), which provides us with cost estimates for different home improvement projects, such as installing underfloor heating, based on the price of labour and materials.

According to its data, water underfloor heating is around 25% more expensive to install per m2 than electric underfloor heating. 

See the actual costs in our guide to underfloor heating costs and installation. 

Where can you install underfloor heating?

You can install both types of underfloor heating almost anywhere in your home. 

Electric underfloor heating is typically less bulky than water systems, which is useful for rooms with low ceilings if you're not keen on raising the level of your floor. 

Insulation for electric systems can be as little as 25mm thick and the wire itself 4-5mm thick, whereas water systems can be around 130mm thick – or even thicker if they are being retrofitted under an existing floor. 

Running costs

Although water underfloor heating is more expensive to install than electric underfloor heating, it is usually cheaper to run. 

Based on estimates from underfloor heating manufacturers on how much hot water you'd need, we've calculated that the annual running costs for water underfloor heating for a 10m2 room can be as low as £45 over a year. 

This is significantly cheaper than electric underfloor heating, which in an equivalent sized room can cost as much as 36p per hour – or £33 a month if you used it for three hours a day.

Actual running costs for underfloor heating systems will vary considerably, as they are impacted by factors such as:

• Your home's insulation
• The size of the area to be heated
• How long the system runs for
• Your gas and electric tariff

Check our guide to underfloor heating costs and installation to find out the typical prices for different scenarios based BCIS estimates and reports from real users

User reviews of water and electric underfloor heating

It can be difficult to know whether the benefits of water underfloor heating are worth the investment until you've already made the decision. 

In May 2024, we asked 41 Which? members with water underfloor heating and 77 members with electric underfloor heating whether they thought it had been a worthwhile investment. 

You will need to log in or join Which? for access to our user reviews.

In total, 69% of the users of one type of system reported that they were very satisfied with their underfloor heating. Users of the other system were slightly less satisfied. 

Users also reported that each system had different advantages and disadvantages. Both sets of users recommended using a timer – but in different ways. 

You will need to log in or join Which? for access to these insights 

Underfloor heating questions answered

How long does underfloor heating take to warm up?

Water underfloor heating typically takes 2-4 hours to warm up. 

It is generally recommended that you run your heating on a schedule so your house is never uncomfortably cold while you wait for it to warm up. However, the system retains heat for a long time, as the warm water remains in the pipes. 

Electric underfloor heating typically takes 30-90 minutes to warm up, depending on factors like insulation, floor material and system power. 

Thinner flooring materials like tiles or laminate heat up faster than thicker materials like concrete. 

Can you retrofit underfloor heating?

Yes, underfloor heating can be retrofitted. 

This means the system can be fitted within the subfloor, without taking up floorboards or digging up the floor of your home. However, only certain systems can be fitted in this way. 

Electric underfloor heating is much easier to retrofit, and in some cases can be fitted over your flooring. 

However, only certain low-profile water systems can be fitted in this way; the majority of systems are better fitted when you are already renovating your floor. 

Does underfloor heating need a special type of boiler?

No. Underfloor heating works perfectly well with the types of boilers that most people already have in their homes, including combi gas boilers, traditional tank-based gas boilers and oil boilers.

However, your existing boiler may need some adjustments to work effectively with the underfloor heating system and, in a few cases, may not be suitable. 

You should always get a professional to assess your heating system's suitability before committing to getting water underfloor heating installed. 

Can you use underfloor heating with wood floors?

No, you can't use electric underfloor heating with solid wood floors. Wood expands and contracts with temperature and humidity changes, so direct heat can cause the wood to warp, crack, or gap over time, especially with thicker planks.

However, you can use electric underfloor heating with engineered wood, as it is designed to be more resilient.