HEAT PUMPS EXPLAINED: A HOMEOWNER'S GUIDE

This guide provides information on electric air source heat pumps and how they can be used in homes for heating and hot water. However, we recognise that heat pumps won’t work for all houses and provide details on alternative approaches that can reduce carbon emissions and help to future-proof homes for the UK’s low carbon future.

In a changing world, it’s important to understand all your options. When making decisions about your home’s heating, being aware of what’s possible means that you can work with an expert installer and ask the right questions to get the system that works best for you and your family.

Meeting Net Zero carbon emissions by 2050

The UK has set out to achieve Net Zero carbon emissions by 2050. A significant part of our emissions comes from using fossil fuels (particularly gas) to heat our homes, and around 85% of UK homes have a gas boiler, so big changes are needed to meet our national target.

To help householders make the switch from gas and oil boilers to low-carbon, efficient heat pumps it is offering financial help in the form of the Boiler Upgrade Scheme towards the cost of a heat pump.

Switching away from fossil fuels means the UK is also changing how it produces electricity. Once we relied heavily on coal and gas to do this, but today wind power is greening our grid. As a result, adopting electric heating is considered an important step forward for UK households.

The government is already legislating for new homes to use electric heat pump technologies from 2025. However, the greatest challenge is upgrading our existing housing stock by encouraging homeowners to re-think traditional gas, LPG or oil boiler use.

What is an air source heat pump?

An air source heat pump (ASHP) is a system that takes low-temperature heat from the outdoor air and increases that heat energy-efficiently. This heat can be transferred to water that circulates around radiators or an underfloor heating system in your home.

Is a heat pump suitable for my home?

How does an air source heat pump work?

A heat pump uses electricity to drive a compressor that raises the temperature of that outdoor heat energy very efficiently. It operates a lot like your refrigerator, but in reverse. It works so well that it can extract energy from the air even in low winter temperatures.

How efficient are air source heat pumps?

The exact efficiency of a heat pump depends on the system (for example, whether it uses radiators or underfloor heating) and the outdoor and indoor temperature difference. But, on average, 1 kilowatt of electricity can produce approximately 3 kilowatts of heat.

The air-to-water type is the most common heat pump used in UK homes today. This has an outdoor unit (about 1m wide by 1m tall and 350mm deep) that collects heat from the outdoor air and raises the temperature to heat water for your radiators or underfloor heating. It can also provide hot water to a cylinder in your home for showers and hot taps.

Because they’re electrically powered, heat pumps can use the UK’s wind-generated electricity, making them a low-carbon heating system. It is also possible to use electricity from solar panels (photovoltaics or ‘PVs’) which could be mounted on the roof of the house. Unlike a fossil fuel gas or oil boiler, heat pumps produce zero carbon emissions at your home.

What’s involved in a heat pump installation?

If you’re considering a heat pump for your home, it’s essential to work with a knowledgeable installer who can advise how a heat pump might meet your heating and hot water needs and on what will work best for you.

1. Assessing whether your home is suitable
   The first question is whether your home is suitable for a heat pump because its performance can be affected by insulation levels. A traditional boiler-and-radiator system generally runs at around 70ºC to 80ºC; a heat pump system recommended temperature is between 35ºC to 55ºC. So, a house must be well insulated for the heat pump to provide a comfortable indoor temperature.
2. Making sure your home is correctly insulated
   Investing in loft insulation and modern windows and doors would be another important first step if your home does not have these already. These will also go some way to lowering your heating bills and making your home more comfortable, whatever heating system you use, so this could be an excellent first step.
3. Replacing old radiators
   Depending on the age of your property, a heat pump installation may also require replacing older radiators with larger and more effective models to ensure the system operates efficiently at lower system temperatures.
4. Installing a hot water cylinder if you don’t have one
   In addition, if you don’t currently have a hot water cylinder (for example, if you have a combi-boiler that heats water as you need it), then you would also probably have to have one fitted if the heat pump is providing hot water as well as heating. Your installer will also take into account how much hot water your household uses to advise on the size of the cylinder needed.
5. Finding an outdoor spot for the unit
   A final point to remember is that an air-source heat pump heating system includes an outdoor unit, around 1m x 1m x 350mm in size. Ideally, the outdoor unit should be placed close to the house with clearances to allow good airflow, so a spot without plants or bushes is best. Of course, a garden or outside space is an advantage, but there are units that can fit onto walls or balconies in apartment blocks.

Does installing a heat pump require planning permission?

Installation of a single air source heat pump on domestic premises is a ‘permitted development’, so it does not typically require planning permission if the installation complies with the Microgeneration Certification Scheme Planning Standards (MCS 020). Under these rules, the heat pump must also be used only for heating purposes (some models can also provide cooling).

The permitted development rule applies to the installation of a new or replacement air-source heat pump for a house or block of flats (where the block consists solely of flats and does not include commercial premises). It is a good idea to check with your local planning authority to ensure all these limits and requirements will be met.

What if my home is not suitable for a heat pump?

Not all homeowners will be able to swap out a boiler for a heat pump. This could be because the house is difficult to insulate to the required levels due to age or construction type, or a heat pump can’t meet your household’s hot water requirements.

It may also be the case that you don’t want to move away entirely from using a gas or LPG boiler. For instance, you may not be able to easily find room to fit a new hot water cylinder if you don’t currently have one.

Hybrid options

In these cases, it could be an excellent time to consider a hybrid system, which uses a heat pump in combination with a gas boiler. If your home is off the gas grid, it’s an approach that also works well with an LPG boiler.

In a hybrid system, the heat pump can provide the heating while the boiler produces hot water. This removes the challenge of adding the water cylinder since a gas combi-boiler could still provide hot water when needed.

Using these two technologies in tandem is also a good option for a home with high heating demand. For this type of property, perhaps an older construction-type building, including a boiler in the system, means that during peak demand, in cold weather, for example, the boiler can boost the heating in your home, keeping it comfortable.

An additional option to consider is that it’s possible to include solar photovoltaics (PVs) in this approach, as they can provide a proportion of the electricity for the heat pump element of the system. This reduces your home’s grid electricity consumption, energy costs, and carbon footprint.

One of the benefits of a hybrid system is that it can automatically switch between ‘fuels’, depending on which is the most cost-effective at any time. However, with the hybrid approach, it’s vital to work with an installer who understands the requirements of this system. They will ensure that it’s set up for optimum performance.

The future of heat pumps in the UK

Will a heat pump reduce my energy bills?

One of the critical questions householders ask is whether switching to a heat pump heating system will reduce energy bills.

Heat pumps are energy efficient, using 1 kilowatt of electricity to produce approximately 3 kilowatts of heat. As a result, they are more cost-effective than oil-based heating or direct electric equipment such as storage heaters, fan heaters or underfloor mat types. For homes off the gas grid, an electric heat pump can reduce running costs.

However, in the UK, the unit rate of domestic electricity is around four times more expensive per kilowatt hour than gas. This means that, in the early 2020s, even though a heat pump is very efficient, it may be more expensive to operate in some cases than a gas boiler.

Government plans

The government has recognised this problem of high electricity prices and their impact on heat pump use. As a result, it is planning to change subsidy rules for energy production, making electricity from renewables such as wind a more cost-effective option.

This is in addition to the existing government energy strategy of reducing the UK’s reliance on natural gas which will see a faster shift to renewable electricity production. Therefore, we will likely see gas prices rising in the next few years to a point where they overtake electricity prices. At that tipping point, it would make sense to consider lowering energy bills by switching to an electric heat pump.

Another approach is to consider making your own electricity. As an electric heating system, solar panels (photovoltaics) can also power heat pumps. This could be cost-effective depending on heating, hot water needs, and the number of solar panels. However, the initial installation costs and property suitability would have to be considered.

Futureproofing your home

Energy costs are one of many considerations for householders thinking about heating options. In addition, as the UK changes its energy infrastructure, homeowners must consider future-proofing their homes.

Building Regulations already require new houses to be designed for low-temperature heating systems. Even if not installed with heat pumps, they must be ‘heat pump ready’. It is a factor which may impact the value of existing homes in the long term.

For householders looking at the value of their home investments, now is an important time to consider all options for updating heating systems to be ready for the UK’s low-carbon future.

Hybrid options

Modern domestic heating systems offer a high degree of flexibility. If you’re not ready or able to switch away from a gas, LPG, or oil boiler, then a hybrid approach can help you make the most of two technologies, future-proof your home to retain its value and ensure you’re ready for changing energy prices in the future.