Do you need new radiators with a heat pump in the UK?

Do heat pumps work with radiators?

Yes, heat pumps do work with radiators, but they heat your home a little differently from a traditional gas boiler.

It all comes down to flow temperature. This is the temperature of the hot water as it leaves your heating system and circulates through your radiators (or underfloor heating).

Boilers typically run at higher flow temperatures than heat pumps, usually around 50–70 °C, depending on the type of boiler and the time of year. This higher temperature allows standard radiators to heat a room quickly. Heat pumps, however, operate at lower flow temperatures, usually between 35–55 °C. Because the water isn’t as hot, radiators need a larger surface area to release enough heat to keep your home at a comfortable temperature.

This is why some homeowners upgrading to a heat pump need larger radiators. It’s not that radiators don’t work, but that they just need to be correctly sized for a lower-temperature-based system.

How to size radiators for a heat pump

So, do you need new radiators with a heat pump? The answer depends on how your current radiators compare to what’s required for lower flow temperatures.

As a general guide, radiators used with heat pumps often need two to three times the surface area of those paired with a traditional boiler. That doesn’t necessarily mean replacing every radiator, as some may already be large enough, particularly in well-insulated rooms.

The only reliable way to determine this is through a professional heat loss calculation. A heating engineer will assess each room individually, taking into account:

• Building elements such as walls, roof, windows, ceiling, and doors
• Room size and ceiling height (surface area)
• Loft insulation levels
• Ventilation and infiltration
• Desired indoor temperature

This room-by-room assessment ensures the system is correctly designed for your home, helping maximise heating efficiency and comfort.

Are radiators or underfloor heating better with heat pumps?

Radiators can work with heat pumps, but underfloor heating is often a more natural fit. Its larger surface area makes it effective in low-temperature systems. 

In fact, underfloor heating can be up to 40% more efficient than traditional radiators when paired with a heat pump. Lower operating temperatures mean the heat pump doesn’t have to work as hard, which can help reduce running costs over time.

However, underfloor heating isn’t always the most practical option, particularly in homes with existing radiators. Installation can be disruptive and more expensive than upgrading radiators. In many properties, upgrading selected radiators and improving insulation is enough to make a heat pump perform efficiently.

The right choice will depend on your home’s layout, your budget, and your long-term heating goals.

Reliable servicing for your air source heat pump

Whether you upgrade your radiators or not, keeping your heat pump running efficiently is essential.

Regular servicing helps protect efficiency and extend the lifespan of your system, so if you already have a heat pump or are planning to install one, we’re here to keep your home warm and running smoothly.

With our air source heat pump service plans, you can ensure your system is professionally maintained and performing at its best all year round.