Underfloor Heating with a Heat Pump: The Efficiency Gold Standard

Why Underfloor Heating and Heat Pumps Are a Perfect Match

An air source heat pump works at its most efficient when producing water at lower temperatures — typically 35–45°C. This is fundamentally different from a gas boiler, which heats water to 60–75°C. Underfloor heating also operates at low temperatures (25–35°C), making the two systems ideally suited to each other.

When a heat pump operates at lower flow temperatures, its coefficient of performance (CoP) — the ratio of heat output to electricity input — increases significantly. A heat pump running underfloor heating at 35°C might achieve a CoP of 4.5 (4.5 units of heat for every unit of electricity). The same heat pump driving radiators at 55°C might achieve only 2.8. This means underfloor heating can reduce your heat pump's running costs by 20–30%.

How the Combination Works

The system works as follows: the heat pump heats water to the required temperature (typically 35–42°C for underfloor heating), which circulates through pipes embedded in the floor. The large floor surface area radiates gentle, even heat upwards through the room.

Because the heat distribution area is so large (the entire floor), the water only needs to be slightly warmer than room temperature to heat the space effectively. This is the opposite of a traditional radiator, which heats a small surface area to a high temperature.

The combination also pairs well with solar panels — using free solar electricity to run the heat pump during the day pre-heats the thermal mass of the floor, which then releases heat slowly throughout the evening.

What Does It Cost?

The cost depends significantly on whether you are installing in a new build, renovation, or retrofit:

• New build or full renovation: Underfloor heating can be embedded in a screed floor at relatively low cost — typically £50–£80 per m² for the UFH system itself. For a full ground floor (60 m²), this adds £3,000–£5,000 to a build or renovation.
• Extension: The most cost-effective retrofit scenario. UFH in a new extension screed floor is straightforward and well worth doing if you are adding a heat pump at the same time.
• Retrofit in existing rooms: Slim-profile systems (15–20mm) can be laid over existing floors without significant floor height changes. Cost is typically £80–£120 per m², giving £4,800–£7,200 for a 60 m² ground floor. This adds to the overall project but the efficiency gains justify the investment.

When combining with a heat pump installation, we provide a fully integrated quote. See our heat pump costs guide for more detail.

Retrofit Options for Existing Homes

Retrofitting underfloor heating into an existing home is more complex than new build installation, but far from impossible. Modern slim-profile systems significantly reduce disruption. Options include:

• Screed overlay system: A thin (65–80mm) screed poured over existing floor with pipes embedded. Best for ground floors, requires removing skirting boards and trimming doors. Excellent heat performance.
• Overlay panel system: Pre-grooved insulation panels with pipe channels, covered with a thin overlay board. Total depth 15–25mm. Minimal floor height increase, easier to install.
• Suspended floor system: Pipes clipped to underside of timber floor. No height change at floor level. Access needed from below or through existing floorboards.

For older properties with solid stone or concrete floors, screed overlay or suspended systems are typically the best approach. We assess the best method during the free home survey.

Read our guide on heat pumps in older properties for more on retrofitting in period homes.

Underfloor Heating Zones and Controls

A properly designed underfloor heating system uses separate zones — typically one per room or area — each with its own thermostatic control. This allows you to maintain different temperatures in different parts of the house and avoid heating unoccupied rooms.

Modern UFH controls integrate with the heat pump controls to create a truly intelligent heating system. The heat pump can adjust its output based on the collective demand from all zones, running more efficiently in mild weather and responding to occupancy patterns.

Getting the Right Design

The key to a successful underfloor heating and heat pump installation is proper system design. This means accurate heat loss calculations for every room, correctly specified pipe spacing and flow temperatures, and a heat pump sized to match the combined demand.

An undersized heat pump will struggle to maintain comfort on cold days. An oversized one will short-cycle and run inefficiently. The combination of underfloor heating and heat pump is only as good as the design behind it.

We carry out free home surveys across St Austell, Bodmin, Truro, Newquay, and all areas of Cornwall. Every survey includes a heat loss assessment and system design — whether you choose to proceed with us or not.