Different types of heat pumps: An expert guide

If you're considering a heat pump for your home, you'll of course want to choose the best possible type for your needs. To help you decide, we'll explore all of the different kinds of heat pumps available. We'll look at the different sources heat pumps might use, including air, water, and ground, and what each type needs to work properly. We'll also look at monobloc and split heat pumps, two different designs of air source heat pumps, so you can make the most informed choice possible.

In this guide, you'll discover the benefits and disadvantages of each heat pump type, as well as costs, efficiency levels and which type of home each kind is best suited to. For an in-depth look at air-source heat pumps in particular, we have a dedicated expert guide.

Air-source heat pump

Air source heat pumps are compatible with the widest range of homes, requiring only access to outside air, unlike other heat pump types that require large amounts of ground or a nearby body of water.

How does an air source heat pump work?

Heat pumps extract energy from the air using substances called refrigerants that have very low boiling points.

As air passes through the heat pump, energy is transferred to the refrigerant, causing it to boil and become a gas. It’s then compressed to increase the energy and temperature even more, and this energy is then transferred to the water that will flow around the heating system, while the refrigerant cools enough to return to a liquid form for the cycle to begin again.

They are usually over 300% efficient, meaning that their heat energy output is three times the electrical energy input, significantly cutting back on your carbon emissions. A gas boiler, by comparison, is typically under 100% efficient.  You can read our guide comparing heat pumps to gas boilers, as well as our guide explaining how heat pumps work in winter and cold weather, to understand more.

According to the Energy Saving Trust, the average air-source heat pump costs £12,000. However, by accessing the Government's Boiler Upgrade Scheme, you can reduce this by £7,500. See our guide explaining heat pump costs for more information.

Ground-source heat pump

Ground-source heat pumps are less common than air-source heat pumps. They are 350% efficient on average but have a hefty cost of around £28,000, although this can be somewhat mitigated by the £7,500 Government boiler upgrade scheme.

How does a ground-source heat pump work?

Ground-source heat pumps use pipes to draw heat from the ground outside your home, making them more consistently efficient across seasons than their air-source counterparts. However, the installation process needed for this is extremely invasive.

The average 3-bed home would need 400 square metres of ground area for horizontally laid pipes or boreholes reaching 80-160 metres downward for a vertical system, making them unsuitable for many properties.

Water-source heat pump

This type of heat pump is among the most efficient, reaching up to 600% efficiency because heat transfers more easily through water. Water-source heat pumps cost £10,000 on average and are eligible for the same Government grant as their air and ground-source counterparts.

How do water-source heat pumps work?

Water-source heat pumps absorb heat from nearby bodies of water such as lakes, rivers, streams, mine water, aquifers or the sea. This results in very consistent efficiency levels or SCOP (Seasonal Coefficiency of Performance) as water temperatures are generally stable throughout the year in the UK. However, it does require the home to be near a body of water, meaning that this is not a feasible heat pump choice for many homeowners.

What type of home is each heat pump best suited to?

Air-source heat pumps are suitable for the widest range of homes, not needing extensive outdoor space or proximity to a suitable body of water. For a more detailed assessment of your home’s suitability for heat pumps, see our guide, 'Should I install a heat pump in my home?'.

Monobloc heat pumps vs split heat pumps

There are several types of air-source heat pumps, most significantly monobloc and split. 

Monobloc heat pumps

A monobloc air source heat pump consists of a single unit outside your home, where the compressor, heat exchanger, and other components are housed.

They’re also usually easier to install than their split counterparts, as your engineer doesn’t have to be F-Gas qualified to fit them. This is because the F-Gas is contained in a sealed unit, meaning you have a wider range of engineers able to install your monobloc heat pump. 

However, monobloc heat pumps that use R290 refrigerant are complex to install, as this is a flammable substance that requires the installer to have flammable refrigerant qualifications. 

Our Logic Air and HP290 heat pumps are both monobloc types, with the Logic Air offering ease of installation and the HP290 boasting the more efficient and lower-carbon R290 refrigerant. 

Split heat pumps

A split heat pump has both an indoor and outdoor unit, with the refrigerant split between the inside and outside of your home. The outdoor unit collects the heat from the air, and the heated gas is sent to the indoor unit to heat your water. Due to the pipework needed to connect the refrigerant loop, split heat pumps are usually more complicated to install than monobloc versions and are, therefore, more initially expensive.

However, split heat pumps do have a number of benefits. The smaller outdoor unit means that you don’t need to worry as much about having adequate outdoor space, although you will need sufficient indoor space for a hot water cylinder and an indoor unit. The outdoor unit can also be further away from your property, giving you flexibility with your heat pump placement. Both our Alfea Excellia and Alfea Extensa are split pumps.

R290 vs R32 heat pumps

Another consideration when choosing your heat pump is the refrigerant type. While many heat pumps use R32 refrigerant, the highly efficient R290 refrigerant is becoming more and more popular.

R290 boasts zero Ozone Depletion Potential and a Global Warming Potential of just 3 due to its very low carbon content, making it popular among those motivated to switch for environmental reasons. It also has an impressively high flow temperature, up to 75℃, which allows it to work well with traditional radiator systems as well as underfloor heating. 

We use R290 refrigerant in our HP290 domestic heat pump, a monobloc system. You can learn about how this system works and why it’s an amazing choice for sustainability in our guide ‘The HP290 heat pump: Low-carbon heating solutions from Ideal Heating’.

However, that doesn’t mean R32 refrigerant heat pumps aren’t still a strong choice for a range of homes. R32 heat pumps are often smaller and easier to service, as they don’t require specialist hydrocarbon safety and flammable refrigerant qualifications, whereas R290 refrigerant heat pumps do. 

Choose one of Ideal Heating’s heat pumps today for a toasty and efficient home, or see our tips and advice page to learn more about our heating solutions.