Is Underfloor Heating Expensive to Run? UK Costs

Running cost comparison

Take a 10m² bathroom, heated 3 hours a day, as a common reference point:

• Electric UFH: roughly £230 per year
• Wet UFH, gas boiler: roughly £66 per year
• Wet UFH, heat pump: roughly £66 per year
• Radiator, gas: roughly £70 per year

Electric UFH runs at 3-4 times the cost of either wet UFH or a standard radiator. That multiple holds roughly true whether you're heating a small ensuite or a large open-plan kitchen, because it's driven by the cost per unit of energy, not the heating method itself.

Why electric UFH costs so much more

The underlying reason isn't that underfloor heating is inherently expensive. It's that electric UFH runs directly off mains electricity, and UK electricity costs roughly four times as much per kWh as mains gas (around 28p versus 7p per kWh in 2026). Electric resistance heating is close to 100% efficient at converting that electricity into heat, but 100% of an expensive fuel is still more costly than a slightly less efficient use of a cheap one.

Wet UFH sidesteps this by heating water with a gas boiler or a heat pump rather than an electric element. A condensing gas boiler runs at roughly 90% efficiency, so the effective cost works out around 7.8p per kWh of heat delivered. A heat pump does even better on paper: for every 1kWh of electricity it consumes, a typical heat pump paired with underfloor heating delivers around 3.5kWh of heat (its coefficient of performance, or COP), bringing the effective cost down to around 8p per kWh, similar to gas despite running on electricity.

Why wet UFH also runs at a lower flow temperature

Wet UFH circulates water at 35-45°C, compared with 60-70°C for a typical radiator system. Because the pipes are spread across the whole floor area rather than concentrated in a single radiator, they don't need to run as hot to deliver the same amount of heat into the room. Lower flow temperatures mean the boiler (or heat pump) runs more efficiently, and it's part of why wet UFH is often described as the ideal partner for a heat pump specifically, since heat pumps themselves perform best at low flow temperatures.

Is wet UFH actually cheaper than radiators?

Broadly, yes, though the saving is modest rather than dramatic: typically 5-10% versus a comparable radiator system on the same boiler or heat pump. The saving comes from a combination of factors:

• Lower flow temperature, which suits condensing boilers and heat pumps better
• More even heat distribution across the floor, avoiding the cold spots and stratified warm air you get with a single wall-mounted radiator
• Zoned control, letting you heat only the rooms in use rather than the whole system at once

Electric UFH, by contrast, costs 3-4 times more than radiators to run, for the reasons above. It's rarely chosen as a primary whole-house heating method for this reason; it's much more commonly used to heat a single bathroom or kitchen where the comfort of a warm floor outweighs the running cost of a small area.

What actually drives your bill up

Beyond the basic electric-versus-wet choice, a few factors move the numbers a lot in practice:

• Room size and insulation: a poorly insulated room needs the system to run longer to hold temperature, which is the single biggest lever on the bill
• Floor covering: tile and stone conduct heat well; carpet insulates against it, so a carpeted room needs more energy input for the same result (see our UFH under carpet guide)
• Thermostat behaviour: a basic on/off thermostat cycles less efficiently than a programmable one that anticipates when you'll actually be in the room
• Usage pattern: continuous background heating in a well-insulated room can cost less overall than repeated on/off cycling, since UFH has a slow response time and reheating from cold uses more energy than maintaining a steady temperature

Reducing running costs

• Use a programmable thermostat rather than a manual dial; typical saving 15-25%
• Zone the system so unoccupied rooms aren't heated on the same schedule as the rest of the house; typical saving 20-30%
• Insulate properly underneath the UFH pipes or cables; poor insulation sends heat downward into the subfloor rather than up into the room
• Choose tile, stone or LVT over carpet where you have the choice, since these conduct heat far more efficiently
• If you're installing wet UFH from scratch and have the option, pair it with a heat pump rather than a gas boiler for the lowest long-term running cost and lower carbon emissions

For a full breakdown of installation costs alongside running costs, see our underfloor heating cost guide.