1 August 2023

22 heat pump myths debunked

This technology, vital for reaching net zero, is misunderstood.

In the race to a green economy, the UK government has identified heat pumps as the key technology to replace gas boilers, which is how most UK households are heated. In fact, the government has committed itself to installing 600,000 of them a year by 2028. Yet deployment in the UK remains at very low levels, despite growth. The UK ranks bottom in the European heat pump league table, as per figures for 2022.

Part of the problem is that heat pumps are misunderstood. There are many myths about them, spread on social media and via newspapers. Many are false, though a few are at least partially correct. What are these myths?

Myth 1: Heat pumps don’t work in cold climates

This is false. The most per capita heat pumps can be found in the coldest climates. More than half of all households in Norway have one, as our research published in Nature Energy shows. Even at temperatures well below freezing, heat pumps still perform efficiently and effectively as field data from the UK, Germany, Switzerland, Canada, the US, and China demonstrates. For very cold temperatures far below freezing (-20°C or less), systems with some form of back-up may be needed; such temperatures are usually not reached in the UK.

Myth 2: Heat pumps will always need a back-up heating system to keep you warm

This is false. As many as 79 per cent of homes monitored under the UK’s electrification of heating trial have no backup heating system installed and use a heat pump to provide all of their hot water and space heating needs.

Myth 3: Heat pumps don’t work in old or existing buildings

This is false. Results from the UK indicate that there is no significant variation in performance based on house age. I know this from personal experience. Since 2019 I have had a heat pump in my Victorian home, built in 1880, and it performs very well, saving energy, carbon emissions and money. The Fraunhofer Institute in Germany carried out extensive field testing and monitoring of heat pumps in existing buildings and concluded that the heat pumps worked reliably and without problems. Recent trials in the UK confirm this.

Myth 4: Heat pumps only work in highly insulated buildings

This is false. Research shows that extensive renovations are not necessary to install a heat pump. Good fabric efficiency keeps running costs down, as it also does for homes heated by gas and oil boilers.

Myth 5: Heat pumps work with underfloor heating only

This is false. Heat pumps work well with radiators, too, as research shows. In some cases radiators may need upgrading, but it has been common practice for heating system installers to use oversized radiators so not all need upgrading.

Myth 6: Heat pumps won’t keep you warm

This is false. Surveyed households who installed a heat pump reported that they were as comfortable as or more comfortable than before the installation, and 81 per cent said their level of comfort had improved.

Myth 7: Heat pumps are noisy

Ground source heat pumps make very little noise. Air source heat pumps can be quiet, too, as this video shows, and newer models have become a lot quieter. Also remember that heat pumps are installed outside buildings. When you’re out in the garden in the summer, your heat pump is unlikely to be running. If hot water is needed, it could be scheduled for times when you are not outside.

Myth 8: Heat pumps cost more to run and will increase heating bills

Whether or not a heat pump saves a household money depends on a) the efficiency of the system and b) energy prices. Under the current energy price guarantee, a heat pump with an average efficiency saves a household more than £150 per year. This may change depending on how prices develop in the future. It is true that heat pumps are more expensive to buy than gas boilers. The UK government offers subsidies for heat pumps, however, and some companies now offer heat pumps for less than £3,000 after the subsidy. With running costs included, heat pumps can offer lifetime cost savings over fossil fuel systems.

Myth 9: Turning gas to electricity to heat via a heat pump is less efficient than burning gas in a boiler

This is false. A heat pump – even if running 100 per cent on gas electricity – needs about 1/3 less gas than a fossil fuel boiler to make the same amount of heat. The Cambridge professor David MacKay pointed this out in 2008.

Myth 10: Heat pumps devalue properties

This is false. The evidence suggests the opposite. Heat pumps increase the value of properties, as research by the estate agent Savills shows.

Myth 11: The grid cannot cope with heat pumps

This is only partially true, as research commissioned by the UK government has demonstrated. In many places there is sufficient capacity in the grid to supply electricity for additional heat pumps. Yet with significant heat pump uptake, electricity demand will grow and therefore grid investment is needed.

Myth 12: Heat pumps are the only low-carbon solution for heating

This is false. Better fabric efficiency and district heating are very important, too, and can offer large energy system benefits in terms of flexibility and reducing demand at peak times.

Myth 13: Heat pumps cannot be installed in small apartments

This is false. There are projects where tower blocks use ground source heat pumps. Large heat pumps can fuel district heating networks connecting apartments.

Myth 14: Heat pumps will just run on fossil fuel electricity

This is false. It is true that the UK’s electricity still includes a lot of gas generation, but every year substantial amounts of renewables are added to the grid. As a result, a heat pump installed in the UK today will have 77-86 per cent lower carbon emissions than a gas boiler over 15 years.

Myth 15: You will freeze during a power cut and be better off with a gas boiler

It is true that during a power cut heat pumps cannot function, but the same is the case for a gas boiler.

Myth 16: There is no consumer demand for heat pumps

This is false. Last year saw record growth in heat pump sales in Europe and, in the US more than 4 million heat pumps were sold, surpassing gas furnaces for the first time. In the UK demand for heat pumps was up by 40 per cent in 2022.

Myth 17: Heat pumps don’t work with microbore piping

This is only partially true. Microbore piping is not ideal but can be used with a heat pump under certain conditions.

Myth 18: Heat pumps are new and untested technology

This is false. The first heat pump that we would recognise was built by Peter von Rittinger in 1856. Heat pumps have been in UK homes for decades, with the first heat pump installed in Norwich in 1945.

Myth 19: You can just plug in heat pumps and forget about insulation

This is mainly false. Yes, heat pumps can heat any building, even if uninsulated, but at significant cost. Modest fabric efficiency improvements always make sense, which is also true for fossil heating.

Myth 20: Heat pumps don’t last long

This is false. Heat pumps have long lifetimes and can exceed 15 or even 20 years if well maintained, as survey data from the US shows.

Myth 21: Heat pumps will never offset the carbon emissions resulting from making them

This is false. Because the UK’s electricity mix has become a lot cleaner, already the carbon emissions from manufacturing are offset 13 months after replacing a gas boiler with a heat pump.

Myth 22: A heat pump needs to stay on all the time

You never switch a heat pump off manually, but this does not mean the heat pump is operating all the time. The system automatically adjusts to outdoor and indoor temperatures and shuts down when it is warmer.

This article was originally published on 24 May 2023.