Chris Harvey of Stelrad Radiator Group examines the relationship between radiators and heat pumps, and how they might be able to work effectively together in future
The recent announcement from the Government of a £5,000 grant available from April 2022 for those installing a heat pump – rather than a traditional fossil fuel driven heating system – has raised the possibility of a significant increase in heat pump installations in the UK. Fewer heat pumps have been installed in the UK in recent years than in any other country in Europe, but the Government wants to see 600,000 heat pumps installed every year from 2028.
The development of lower temperature heating systems, utilising renewable heating appliances such as air source heat pumps – has given rise to a number of questions including where do currently used components fit into the future of heating? Many people claim that underfloor heating is the only or ‘best solution’ for heat pump installations, but that is not the case.
Heating solutions for homes
More than 90% of all heating systems in the UK currently rely on radiators to share the heat around the home, and despite the arrival of underfloor heating, there is still a marked reluctance to use UFH upstairs in new build. It is also a complex option to fit as a retrofit solution, so radiators tend to win out most of the time. Radiators heat up and cool down far more quickly than underfloor heating, something that needs to be borne in mind when selecting the best way to share heat around the home.
Most radiators are actually ‘convectors.’ More than 80% of the heat is convected; drawn up behind the radiator where the air passes over the metal surfaces of the radiator and heats the air in the room.
In new build housing, using a heat pump-based solution is relatively simple. The heating system can be designed into the home at the outset so you know the parameters in which the heating system has to operate – the method of construction, the size of the rooms, the number, type and size of doors and windows – so the heat loss calculations can be done up front and radiators sized accordingly.
The key to radiators operating well in any situation is to size them properly at the outset. This involves accurately working out heat loss calculations to achieve the necessary number of BTUs required to provide comfort heating in each room and to select a radiator that can provide that level of heating.
In replacement heating systems for older properties there are additional issues. It’s a fact that simply replacing a boiler with a heat pump will usually see the existing radiators unable to provide the levels of heat needed in a home. So what is the solution – one that is cost effective and straightforward? Do we need to ditch radiators altogether and look for alternatives?
Radiators & heat pumps
The simple answer is no. Radiators will work well with heat pumps, but the size of the radiators will need to be increased to provide a larger metal surface area to heat the air in the room to the level required to provide comfort heating. This need not involve unsightly radiators – for one, modern radiators are aesthetically far more attractive anyway, but there are other solutions too. You can achieve the extra boost radiators need by replacing the existing single or double panel radiators with the relatively new K3 radiators that have three panels and three sets of fins – providing the additional metal surfaces you need but without increasing the radiator footprint on the wall.
Major radiator manufacturers have anticipated the significant move towards air source heat pumps in the UK and have added new, larger size radiators to their portfolio. They have also stepped up the options on the K3 radiator designs available too.
In addition, the popularity of vertical radiators has also offered a solution. With a smaller horizontal footprint than a traditional radiator, they can also be larger overall – taking up floor to ceiling space instead. It may be more practical and more attractive to have two modern vertical radiators in a room than one large standard radiator.
Radiators are very much ‘fit for the future’ but as always, correct sizing will need to be undertaken to ensure that they are effective. Radiators can work well with air source heat pumps and they already are in a host of installations across the UK.
Chris Harvey is head of marketing of Stelrad Radiator Group