Can heat pumps be used with radiators?

17 January 2023
Can heat pumps be used with radiators?

Can heat pumps be used with radiators?

A heat pump being installedA heat pump being installed

The UK government's planned phasing out of gas boilers later this decade has led to much discussion of alternative heating methods to ensure our homes stay warm through the coldest months. One of the leading alternative methods that has been hitting the news recently are air-source heat pumps. This has naturally caused people to have many questions about how air source heat pumps work and whether they work with radiators. In this article, we'll aim to make this a little clearer and give you a greater understanding of the matter.

What is an air source heat pump?

In very simple terms, an air source heat pump is a unit that sits on the outside of your house looking a lot like the exterior part of an air-conditioning system. These types of heat pump work by taking in the cold outside air, converting it into a fluid which is then compressed in order to heat it up. The hot fluid is then pumped around the pipes in your house and into your radiators, heating up your home.

The reason heat pumps are seen as an eco-friendlier version than traditional gas boilers is because they run on electricity and do not rely on a fossil fuel (i.e. gas) that is extracted from the ground. Air source heat pumps are also much more energy efficient than gas boilers, so even if they use electricity that comes from an coal-fired power generator, they're carbon emissions are far, far lower than gas boilers. They are also suitable to be powered by solar or wind energy, which would reduce carbon emissions to virtually zero.

What's the controversy around heat pumps?

In theory this all sounds fantastic as, by using an air source heat pump, we'd all be heating our homes much more efficiently and in a far more environmentally-friendly manner. However, the biggest objection to heat pumps is the very high upfront installation costs which are quite simply unaffordable for most people. The Government have announced a subsidy scheme to help with the costs, but at the time f writing, the scheme has been criticised for being woefully insufficient.

Additionally, the outdoor part of the system, along with the necessary indoor heat exchanger and water cylinder take up more space than a conventional combi gas boiler, so there are concerns for people in smaller properties or in blocks of flats that there won't be enough space to accommodate all the necessary components.

While the 'gas boiler ban' refers to new-build properties and won't force people in existing properties to remove their gas boilers, encouraging people to voluntarily move over to air source heat pumps will require a lot of effort and incentive.

Do radiators work with heat pumps?

Radiators do indeed work with heat pumps and will continue to be the preferred way of emitting heat into a room long after heat pumps are installed in homes. As previously mentioned, heat pumps convert cold air into a hot fluid in order to generate heat. This hot fluid still need to be distributed around the pipes in your home and will still need to flow into radiators in order to get rooms nice and warm.

Another big question many people have is whether their existing radiators will work with a heat pump. This is one of those 'it depends' situations.

To give a bit of context, the temperature of the water flowing around your pipe network needs to be higher when using a gas boiler than it does in an air source heat pump. You may see this expressed as a 'high flow temperature' vs a 'low flow temperature and is one of the big reasons heat pumps are considered more efficient than boilers. With heat pumps, the water doesn't need to be heated to such a high degree in order to heat a home sufficiently than it does with gas boilers.

Your existing radiators were installed to ensure that their heat outputs were large enough to heat your room when the flow temperature from your boiler is high (typically around 65 - 70°C). However, when using a heat pump, the flow temperature is much lower (typically around 40 - 50°C) so you would need to ensure that your radiators are still able to heat your room effectively.

In some cases you would need to upgrade your radiators to a larger size to ensure they had enough surface area to emit enough heat out to comfortably warm the room. However, it has been common practise in recent years for heating installers to 'oversize' radiators when installing new central heating systems and gas boilers. This basically means that the radiators are actually capable of heating a much larger space and would therefore be suitable of heating a room even if they operated at a low flow temperature. If your radiators have been 'oversized' then it is very likely you wouldn't need to change them to accommodate an air source heat pump. The best way to find out is to speak to a professional heat pump installer to get a definitive answer.

High output radiators at Trade Radiators

A Type 22 Convector Radiator with high heat output

One of the most popular high heat output radiators we offer are white 'Type 22' convector radiators. These are conventional radiators that come with two panels and two rows of convector fins (hence the '22' in the name) to maximise heat output. The larger the dimensions, the greater the heat output and these are the best option for 'oversizing' your room.

Many of our convector radiators com with stylish side panels and top grills that neatly box in your rads and conveniently hide the internal convector fins. We particularly recommend Type 22 radiators for frequently-used downstairs rooms that need a good level of heat in throughout the day, though these convector rads are highly suited to any room in need (or potentially in need) of high heat outputs.


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