What Is A Heat Pump? Written by Tatiana Lebreton Updated on 3 October 2023 ✔ A heat pump is a fossil fuel-free home heating system✔ The most common types in the UK are air source and ground source heat pumps✔ Heat pumps cost anywhere from £1,600 to £35,000, depending on the typeHeat pumps are set to become a common feature of homes – and why not, when they can pluck heat from the air, ground, or water, and turn it into a clean, unlimited source of energy? And with the government helping with the upfront cost of heat pumps, it's never been easier to invest.If you want to join the thousands of UK homeowners currently using heat pumps, you’re in luck. It’s never been easier to compare prices with our easy-to-navigate tool. All you have to do is provide a few quick details, and our expert installers will be in touch with free quotes for you to compare. What type of central heating do you currently use? Gas boiler Electric boiler Oil boiler Other / not sure Get started What’s on this page? 01 What is a heat pump? 02 How does a heat pump work? 03 Types of heat pumps 04 What are the pros and cons of heat pumps? 05 How much does a heat pump cost? 06 Are there grants for heat pumps? 07 How are heat pumps installed? 08 How many homes in the UK have heat pumps? 09 Next steps 10 FAQs What is a heat pump?A heat pump is a machine that draws heat from outside – from the air, ground, or water for example – and uses it to warm your home’s heating and hot water systems.You can think of it this type of system as the opposite of an air conditioner, which takes hot air from inside your home, cools some of it, and directs the rest outside.Heat pumps absorb outside heat, heat it up even more, and transfer it to your home’s heating network. How does a heat pump work?The heat pump draws heat from the outsideIt uses the heat its drawn to heat up a liquid refrigerant, turning it into a gasThe gas refrigerant is transferred to a compressor, which heats up the gas even moreThe hot gas moves to a heat exchanger, which transfers the heat to the home’s heating network and hot water systemWhen the heat transfer is complete, the temperature of the gas drops, and it turns back into a liquid to be used againThe heat extraction process varies depending on the type of heat pump. Different types of heat pumps extract heat from different outside sources (air, the ground, water), but once they have it, they more or less function the same way.All heat pumps, except air-to-air heat pumps, are designed to work as part of a ‘wet heat system’. This means that they heat water, which flows to radiators throughout the house.Air-to-air heat pumps operate as part of a ‘dry heat system’, which means they heat air, which is sent to rooms in the house through vents or ducts.Crucially, all heat pumps are powered by electricity. They don’t use electricity to generate heat, the way an electric radiator does, but they use it to power the systems that extract and transfer heat. What type of central heating do you currently use? Gas boiler Electric boiler Oil boiler Other / not sure Get started Types of heat pumpsThe four types of heat pumps are:Air source heat pumpsGround source heat pumpsAir-to-air heat pumpsWater source heat pumpsAir source heat pumps draw heat from the outside air, and use it to heat your home. They can do this at temperatures as low as -25°C, although they typically have to work harder when temperatures go below freezing.Ground source heat pumps draw heat from the ground through a loop or borehole system that’s buried in the land surrounding the home. When it’s 0°C outside, the ground temperature usually stays at a comfortable 10°C, which makes ground source heat pumps more efficient in winter than air source heat pumps.Air-to-air heat pumps draw heat from the air, the same way air source heat pumps do. The key difference is that air-to-air heat pumps send hot air through air ducts in the house, instead of heating the water that flows to radiators.These means you'll need a separate system to heat water for bathrooms, such as a heat pump water heater.Air-to-air heat pumps can also be used for air conditioning in the summer, since they can switch from producing hot air to producing cool air.Water source heat pumps draw heat from a nearby water source, such as a pond, lake, or river. They’re the most efficient type of heat pump, because water transfers heat very effectively, and usually stays warmer than both the air and the ground in winter.For specifics on the different types of heat pumps, visit our full guide. What are the pros and cons of heat pumps? Pros You’ll typically cut your carbon footprint by 44% You’ll be future-proofed against the gas boiler phaseout You can get £7,500 off the cost of certain types of heat pumps with the Boiler Upgrade Scheme Last longer than a boiler – up the 35 years for air source heat pumps, compared to 13 years for a gas boiler Low maintenance Cons Expensive to buy and install More expensive to run that a boiler – electricity is more expensive than gas Often requires you to install new, larger radiators or underfloor heating They tend to lose efficiency in winter, when you need them most How much does a heat pump cost?Heat pumps cost between £1,600 and £35,000, depending on their size and the type of heat pump.Air source heat pumps cost £10,00 for the average three-bedroom house, and go up to £15,000 for a five bedroom. Water source heat pumps have a similar price range.Ground source heat pumps are more expensive than air source ones, costing anywhere from £17,000 to £35,000.Air-to-air heat pumps are cheaper than other types, costing between £1,600 and £3,100 (assuming you don’t need to install a new air duct system). Are there grants for heat pumps?Yes, there are several grants for heat pumps.The government's Boiler Upgrade Scheme is the main grant for heat pumps. It will reduce the cost an air, ground, or water source heat pumps by £7,500.This is a substantial amount. It means that an air source heat pump will cost the average homeowner £2,500 instead of £10,000, making it cheaper than a gas boiler.There are a few other heat pump grants for low-income families, including the nationwide ECO4 Scheme, Nest in Wales, and Warmer Homes Scotland in Scotland. How are heat pumps installed?The first step is to hire a qualified installer, as this is a job that’s worth leaving to a specialist.They will assess your property and determine the right size heat pump for your home.When installing an air source heat pump or an air-to-air heat pump, the installer will find an appropriate place outside the property for the outside unit, where it has all the space it needs to constantly access a good flow of air.Installing ground source heat pumps is a little more complicated. The installers will have to excavate an area of ground in your property to lay the pipework that will absorb heat. These can be vertical boreholes or a horizontal loop system.A little bit of excavation is also required for water source heat pumps. A loops of pipes that collects heat will have to be placed in the nearby water source, and these will be connected to your house through pipes buried in the ground.Ultimately, all heat pumps are then plugged into the mains, and connected to the heating network inside your home via the necessary pipes and cables.Your installer will then set you up with at least one control panel or thermostat inside your home, so you can check and alter the way your pump is running.In the case of air source heat pumps and air-to-air heat pumps, the entire process should take between one and two days, depending on the size of your home.The process might take up to a week for ground or water source heat pumps. How many homes in the UK have heat pumps?Over 200,000 heat pumps have so far been installed in the UK, and this number is set to grow.The government has set a goal to install 600,000 heat pumps per year by 2028, and is planning to phaseout gas boilers by 80% by 2035.This means millions of people across the UK will need another way of heating their homes.However, as it stands, only half of people are aware of heat pumps, even if these machines are becoming increasingly popular – and for good reason.As we move towards a time when the UK is responsible for net-zero carbon emissions, you can future-proof your home by getting a potentially 100% renewable source of electricity – all while cutting your energy bills.And it’s not just in the UK. The number of households buying air source heat pumps in North America, Europe, and northern Asia is set to triple by 2025, according to the International Energy Agency.By 2030, 22% of homes in these regions will have air source heat pumps. Next stepsYou’re ready. You have all the knowledge you need, right at your fingertips, and you’re fully prepared to save money and CO2 by purchasing a new heat pump.Find the model you want, an MCS-certified installer to put it in place, and before you know it, you’ll be making your wallet and the Earth a better place.To speed up the process, try using our custom-built tool. All you have to do is provide a few quick details, and we’ll put you in touch with our heat pump suppliers, who will send you free quotes. FAQs Do heat pumps work with radiators? Air, ground, and water source heat pumps all work with radiators. They’re designed to be integrated into the home’s existing heating system.However, heat pumps typically require radiators that are 2.5 times larger than standard.Why? Well, heat pumps produce heat at a lower temperature, and release it more slowly than a boiler. So, for a room to achieve the same level of warmth as it would with a boiler, the heat releasing surface (in this case the radiator) needs to be larger. What homes are not suitable for a heat pump? Poorly insulated homes are generally not suitable for a heat pump. Heat pumps produce heat at lower temperatures than boilers, so if a home is poorly insulated, the heat pump might not be able to keep it at a comfortable temperature for the inhabitants.That being said, all homes can be made suitable for heat pumps through insulating measures, such as double glazing, and floor or wall insulation.Read more about if UK housing is suitable for heat pumps or not on our page. How noisy is a heat pump? Heat pumps are not very noisy. They produce a low hum, around 40 decibels. This can go up to 60 decibels when the heat pump is working hard.For reference, that's around the same level of noise a fridge produces. Written by: Tatiana Lebreton Tatiana has written about multiple environmental topics, including heat pumps, energy-efficient household products, and solar panels. She is dedicated to demystifying green tech to make eco-friendly living more accessible.