Matching radiators to heat pump systems


04 June 2021

Steve Charles – Technical Sales Manager, Jaga UK explains why heat pumps are a proven and commercially viable way to transform the way we heat our buildings.

Whilst we know this currently, fewer than one per cent of homes in England use one. Thanks to government policy, rising fuel costs, and a shift towards a more decarbonised grid, this is all set to change, particularly with the ambitious government targets of increasing installation from 30,000 units per year to 600,000 per year by 2028 in the drive to meet net zero carbon emissions by 2050. 

Which emitters can be used with heat pumps?

Heat pumps can provide a comfortable indoor climate, offering significant efficiencies in energy usage and cost savings…. but only when partnered with complimentary heat emitters. Despite the increasing popularity of heat pumps, the topic of which emitters should be used when installing them is still widely misunderstood.

Heat pumps work most efficiently, for example; with a higher Coefficient of Performance, when they distribute heat at lower temperatures; 45/35ºC as opposed to the higher 75/65ºC temperatures produced by gas and oil boilers. It is a common misconception therefore, that the only way to achieve comfortable room temperatures when using a heat pump system, is to choose emitters with a larger surface area, either by oversizing steel panel radiators, which can take up valuable space and ruin the aesthetics of a room, or by opting for underfloor heating, which may not provide the best thermal comfort, and has slow reaction speeds.

But there is in fact an alternative, far more cost effective, energy efficient option that’s quick to install, compact, lightweight, and stylish and will easily reach the required room temperatures when using a heat pump system – low water content (Low-H₂O) radiators.

Less energy, less water, higher outputs

Unlike traditional steel panel radiators, Low-H₂O radiators, like Jaga’s are designed to work effectively with lower flow temperatures. They contain 90 per cent less water than steel panel radiators and of course, significantly less than underfloor heating, meaning they are much faster to heat up and cool down. This provides improved comfort with less energy consumption, no wasteful over-heating and reduced demand on the heating system itself.

Low-H₂O radiators use a compact aluminium and copper heat exchanger which rapidly heats any space – no heavy steel panels requiring pre-heating. Fewer raw materials mean they are far lighter to install and remain much lighter when fully filled during use.

Proven effectiveness

Low-H₂O radiators have been tested extensively across the world and have been proven to be more economical at any water temperature, providing significant energy savings when paired with a heat pump system.

Studies conducted by BRE – the world-leading building research centre – and KIWA – the independent energy testing and certification company – have shown that our Low-H₂O radiators are up to 16 per cent more economical compared to standard steel panel radiators, as they are able to achieve the desired temperature more rapidly, and less heat is wasted through unnecessary over-heating. In 2016, KIWA named them the ‘World’s Most Economic Radiator’.

Boosted outputs with smaller radiators

Although, when correctly sized, these radiators can often comfortably heat a room when paired with a heat pump system, there’s a way to actually reduce the size of the radiator, whilst generating greater outputs. That’s with Jaga’s new Dynamic Boost Hybrid (DBH) technology.

Just launched in the UK this month, DBH is a world first. A booster set which can be retrofitted inside almost all Low-H₂O radiators, which not only increases the heating output of the radiator by two to three times, but can also transform the radiator into a complete climate system, with the ability to provide light cooling (non-condensing) as well as rapid heating with any heat pump that can supply cooling water.

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The pioneering technology utilises small electric thermal activators placed inside the radiator to significantly boost the output without increasing radiator size.

As an example, to produce 850W output using a 45/35/20ºC heat pump system, a static panel heater would need to be sized at 50cm x 195cm. Whereas a Low-H₂O Strada radiator with fan assist DBH technology would be almost half the size and less than one fifth of the weight.

DBH is not an electric radiator. The activators are only used to boost output when necessary, keeping electricity consumption low and more than compensated for by the energy efficiency of the Low-H2O technology radiator.

It works by boosting natural convection when room temperature needs to change quickly. A microprocessor measures and continuously processes room and water temperature, activating air movement across radiator fins to dramatically improve output. DBH can monitor automatically or be manually boosted, further increasing outputs for 15 minutes.

DBH equipped radiators warm a room up 9 times faster than a steel panel radiator with a comparable output. Unlike other fan assisted radiators, the thermal activators in the DBH are whisper quiet. The noise level increases as the speed setting increases but always remains low, and is even inaudible on lower settings. As a booster set, DBH can be installed prior to decoration or retrofitted. There is no visible pipe work and the control panel is discrete.

The need for cooling

The world is getting warmer and our buildings are now better insulated than ever before. Energy demand for space cooling has more than tripled since 1990, making it the fastest-growing end use in buildings [1]. Due to the growing demand and common use of inefficient air conditioning units, space cooling was responsible for emissions of about 1 Gigatonne of CO2 and nearly 8.5% of total electricity consumption in 2019.

A DBH system is an easy, cost effective and environmentally friendly way to provide refreshingly light cooling for UK buildings, simply by installing it inside new or existing Low-H₂O radiators or perimeter heating units. As long as the heat pump installed has a supply of cooling water, this feature can be used.

What is light cooling?

Light cooling (also referred to as 'non-condensing cooling') is a form of gentle cooling whereby the water temperature is always higher than the condensing temperature (or dew point), usually around 15°C depending on weather conditions, and therefore no condensation water is formed. The energy consumption is lower than with low temperature cooling systems such as air conditioning systems, especially in combination with a ground source heat pump, so it’s an energy-efficient way of cooling that’s ideal in combination with low temperature heating.

DBH can be configured in various ways to best suit the application and needs of the end user. One of these configurations includes a ‘Breeze’ mode. This runs just the fans to provide light air movement and does not depend on water temperature so it’s particularly useful where there is no cooling water (i.e. without a heat pump).


1. IEA (2020), Cooling, IEA, Paris