Underfloor Heating vs Radiators With a Heat Pump: Which Is Better?

The short answer is that underfloor heating pairs better with a heat pump — but that doesn’t mean radiators won’t work. The reason comes down to flow temperature. Heat pumps are most efficient when the gap between outdoor air temperature and system flow temperature is small. Underfloor heating runs comfortably at 35–40°C. Most existing radiator systems were designed for 70–80°C. That gap is what makes the difference, and bridging it is the central challenge of retrofitting a heat pump into a typical UK home.

Why Heat Pumps Love Low Flow Temperatures

Heat pumps transfer thermal energy from the outdoor air (or ground) into your heating system. The higher the temperature they need to achieve in the water circuit, the harder they work and the more electricity they consume. This relationship is captured in the efficiency metric SCOP — and the numbers are significant.

A heat pump running at 35°C flow temperature on a 7°C day might achieve a COP of 4.0 — producing 4 kW of heat for every 1 kW of electricity. Push the flow temperature to 55°C for the same outdoor conditions and that COP might drop to 2.5. That’s a 37% increase in electricity consumption for the same heat output. Over a UK heating season, the difference in running costs can easily reach £200–£400 on a typical semi-detached home.

Underfloor heating operates at these lower flow temperatures by design — the large surface area of the floor radiates heat gently and evenly rather than relying on high-temperature convection from a compact radiator. This is why new builds with underfloor heating are the most straightforward candidates for heat pump installation. See our heat pump suitability guide for a fuller picture of which property types work best.

Can You Use Radiators With a Heat Pump?

Yes — but standard-sized radiators designed for a gas boiler system will likely be undersized for a heat pump running at 45–50°C. A radiator that gives out 1,000W at 70°C might only output 500–600W at 45°C. If your total radiator output at low flow temperature is less than your home’s heat loss on a cold day, the heat pump will either run at higher (less efficient) flow temperatures to compensate, or your home won’t reach target temperature.

The solution is to oversize the radiators. In practice, this means replacing existing radiators with larger equivalents — typically double-panel, double-convector (DPDC or K2) radiators — sized to deliver adequate heat output at 45°C rather than 70°C. A full heat loss calculation room-by-room is the only reliable way to know what size radiator each room needs. This is work for an MCS-certified installer; do not skip it.

An oversized radiator system running at 45°C is perfectly compatible with a heat pump and will achieve good efficiency. It just costs more upfront and requires more work than UFH in new construction.

Underfloor Heating vs Radiators: Head-to-Head

For new builds or full renovations, wet underfloor heating is the clear choice — it’s designed for heat pump flow temperatures from the ground up. For existing properties, oversized radiators are usually the more practical and cost-effective option than ripping up floors.

Retrofitting Underfloor Heating: The Real Costs

Wet (hydronic) underfloor heating in a retrofit involves either screed-embedded pipework or above-floor systems like overlay panels. Both require disruption to existing floors:

• Screeded UFH — pipes embedded in a concrete or liquid screed layer. Adds around 75–100mm floor height. Very effective but highly disruptive; suitable for full renovations only. Cost: typically £60–£100 per m² installed.
• Overlay UFH — thin aluminium-clad panels installed over existing subfloor. Less disruptive, adds 15–25mm floor height. Lower output than screeded systems; requires careful design to confirm adequate heat output. Cost: £40–£70 per m² installed.
• Electric UFH — mat systems that use resistance heating rather than warm water. These do not connect to a heat pump and run at much higher effective cost; they are not relevant to heat pump systems.

For a typical 80m² ground floor, wet UFH retrofit might cost £6,000–£10,000 before the heat pump itself. For many homeowners, this tips the decision firmly in favour of well-chosen oversized radiators — particularly if the existing pipework is already in good condition.

The Energy Saving Trust’s heat pump guidance is worth reviewing before committing to either approach, as is independent advice from an MCS-certified installer who will do a proper heat loss survey.

Hybrid Approaches: Mixing UFH and Radiators

Many UK homes end up with a practical hybrid: underfloor heating on the ground floor (where disruption is acceptable and floor height less constrained) and oversized radiators on upper floors. This works well — the heat pump can serve both circuits via the same manifold, with different flow temperature settings where needed.

Modern heat pumps and smart controls can handle mixed systems effectively. Weather compensation — which adjusts flow temperature based on outdoor temperature — is especially useful for maintaining efficiency across mixed emitter types. The key is to design the system so the UFH circuit can be served at 35–40°C, with radiators sized to work at the same or slightly higher temperature rather than requiring 60°C+.

Some installers use a hydraulic separator or low-loss header to decouple circuits running at different temperatures, allowing the heat pump to serve them independently. This adds some complexity and cost but is a proven approach in well-designed retrofit systems. For more on system design, see our heat pump installation guide.

Insulation: The Factor That Underpins Everything

Whether you choose UFH or oversized radiators, the single biggest factor in whether a heat pump works well is your home’s insulation. A well-insulated home has a low heat loss, which means the emitters (floor or radiators) don’t need to work as hard — and the heat pump can run at lower, more efficient flow temperatures.

The MCS guidance for consumers is clear that a heat loss survey must be carried out before installation. If your home has significant draughts, poor loft insulation, or single-glazed windows, improving these before installing a heat pump will save more money long-term than debating UFH vs radiators. Ofgem and the Boiler Upgrade Scheme both encourage energy efficiency improvements before or alongside heat pump installation.

Which Should You Choose?

Here’s a pragmatic summary for UK homeowners:

• New build or full renovation — install wet UFH throughout. It’s the optimal pairing for a heat pump, costs less when done in new construction, and future-proofs the system.
• Retrofit with solid floors — consider overlay UFH on the ground floor, oversized radiators upstairs. Get a heat loss calculation to confirm the numbers.
• Retrofit with timber suspended floors — oversized radiators are often simpler; under-floor systems with timber subfloors can work but require careful specification.
• Limited budget — oversized radiators are significantly cheaper to install than UFH. Focus budget on a high-SCOP heat pump and radiators sized correctly for low flow temperatures.

The debate about UFH vs radiators matters less than getting the heat loss calculation right and ensuring your emitters — whatever type — are sized for the flow temperature the heat pump will actually run at. An installer who skips this step is one to avoid. For more guidance, see our full heat pump costs breakdown and our dedicated underfloor heating with heat pump guide.