(Updated 05/02/2026)
With the launch of the government’s new Warm Homes initiative, committing £15 billion to upgrade five million homes by 2030, the UK’s ambition to improve energy efficiency is clear, and central to this strategy is a continued commitment to heat pumps as a cornerstone of low-carbon heating.
Historically, there has been a widespread misunderstanding that heat pumps are not suitable for use with Thermostatic Radiator Valves (TRVs) due to perceived efficiency losses. However, emerging new research demonstrates this is not the case.
Recent research commissioned by BEAMA and conducted by the University of Salford highlights the “vital importance of TRVs in enhancing the efficiency of heat pump systems”. This aligns with the view of Bjorn Nielsen, Regional Applications Manager, North Europe at Danfoss, who argues that, far from hindering performance, TRVs can help maintain optimal operating conditions for heat pumps, potentially improving both system efficiency and lifespan.
An uncomfortable truth
In stark contrast to gas boilers, which operate at a much higher temperature, heat pumps typically operate at 35-55°C. As installers well know, heat pumps perform much more efficiently when stop-starts are minimised, which gives the rationale behind the ‘lower temperature, on all the time’ approach that has led to the misconception that TRVs don’t work well with heat pumps. However, BEAMA’s research debunks this claim and shows that TRVs allow room temperatures to be lowered, achieving energy savings of 6-8% for air-source heat pumps (ASHPs) without compromising efficiency, while providing a user experience akin to traditional gas heating systems.
In countries with a long history of heat pump usage, like Sweden, they have learnt the importance of resident comfort, and it appears comfort cannot be measured solely by Coefficient of Performance (COP). Even highly efficient systems fall short if one room is freezing while another is overheating. Thermostatic Radiator Valves (TRVs) remain a cost-effective solution, provided their use is carefully adapted to the specific requirements of heat pump systems.
Considerations when using TRVs with heat pumps
A common concern among installers is that TRVs might cause heat pumps to cycle more frequently, potentially increasing power consumption and reducing COP. However, operating without TRVs often leads to imbalanced heating, prompting installers to raise the flow temperature to maintain overall comfort. This can reduce efficiency and create energy losses due to temperature overshoot in some rooms. Maintaining comfort across all rooms is therefore essential, and the key to a successful heat pump retrofit lies in balancing energy efficiency with precise temperature control. TRVs play a central role in achieving this balance.
BEAMA’s research findings confirmed that TRVs can improve comfort management, reduce energy costs, and support decarbonisation goals, all without complex system redesigns. Installers are advised to lower the heat pump’s flow temperature, adjust timers, and use TRVs for precise control, while ensuring adequate water volume and, where appropriate, incorporating a buffer tank. A buffer tank acts as a heat “battery,” allowing air-to-water heat pumps to draw on stored heat during defrost cycles, enhancing system performance and longevity at minimal additional cost. Self-balancing TRVs, such as Danfoss RAS-B2, or e-TRVs can further minimise efficiency losses, ensuring that each room receives the heating it needs while supporting the system’s low-carbon objectives.
Benefits of combining TRVs and heat pumps
Improved System Performance and Durability: When properly balanced, TRVs can help maintain optimal operating conditions for heat pumps, potentially enhancing their overall performance and lifespan.
Efficiency at Lower Temperatures: Modern TRVs are designed to function effectively within the operating range of heat pumps. They can accurately sense room temperatures and adjust radiator output, accordingly, ensuring optimal comfort without unnecessary energy consumption.
Enhanced Comfort: By integrating TRVs, installers can provide a more comfortable environment for occupants. TRVs prevent overheating in individual rooms, ensuring that spaces are heated to the desired temperature without wasting energy. This is especially important in homes where some rooms may be used less frequently.
Compatibility with Smart Technology: Many modern TRVs are compatible with smart heating systems, allowing for remote control and programming. This feature enhances the efficiency of heat pump systems, as users can adjust settings based on occupancy patterns and preferences. Using e-TRVS with heat pumps and smart heating technology can compound the benefits to maximise resident comfort and minimise energy usage effortlessly.
Enabling comfort across hybrid systems: Increasingly, many homes have hybrid systems, for example where an extension has been built. Using TRVs and smart heating controls can be a game-changer for homeowners who need to combine different systems while maintaining comfort and maximising energy efficiency. Without TRVs it can be incredibly difficult to strike the right balance in this context.
An initiative that would further help to optimise TRV and heat pump compatibility would be if a universal standard communication protocol can be developed. At present, too many heat pump manufacturers are using proprietary communication protocols that make life much harder for installers and homeowners.
Size matters
‘Sizing up’ isn’t a problem for gas boiler heating systems, but it most definitely is with heat pumps. Making sure that the heat pump is perfectly sized to the needs of the home will ensure that efficiency is maximised. Radiators also must be correctly sized for the heat output required in each room, which may, in some cases, require the fitting of larger radiators than those used in a gas boiler context. This will allow TRVs to operate efficiently and maintain comfortable temperatures.
The integration of TRVs with heat pumps is not only possible but offers significant comfort benefits to homeowners. By dispelling the myth that TRVs don’t work well with heat pumps, installers can promote energy-efficient, comfortable heating solutions that meet the demands of modern living. Embracing this combination not only enhances system performance but also overcomes some of the barriers to homeowners fully embracing heat pumps as the future of heating technology in domestic settings.
Find out more at: Danfoss – Engineering Tomorrow in United Kingdom and Ireland | Danfoss
