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Which heat pump is best suited for your home?

If you’ve been thinking about modernising your heating system – or installing a new one – then it may be worth considering upgrading to a low carbon system, such as a heat pump.
Heat pump

Heat pumps use energy from the air, ground, or water – and convert these renewable energies into usable heat.

If you’re considering installing a heat pump in your home, you might be wondering what the difference is between them, and which is most suitable for your home.

This guide is to help you decide if a heat pump is suitable for your house, and which out of the three sources would be the best solution.

For further information about heating technology, why not check out our handy heat pump guides:

How does a heat pump work?

Using heat from the air, ground, or water, can reduce the amount of energy required to heat your home. Geothermal energy can be one of the most efficient and environmentally-friendly ways to fulfil your home's heating and hot water needs.

  • The heat from your chosen source is led through a system of pipes with our R290 natural refrigerant, which then evaporates.
  • A compressor increases the temperature.
  • A condensor then transfers this heat to the heating circuit of your home.
  • Having passed the heating circuit, the vapour then reaches an expansion vessel.
  • This expands (or decompresses) the vapour, cools it down and ultimately liquifies it.
  • This allows the refrigerant to absorb the geothermal energy over and over again.

Operating principle of a heat pump

The heat pump draws 75% of its energy from the environment – namely by means of heat from air, water or theground. The remaining 25% is electricity required for operation.

The drawn heat is led through a system of pipes with a refrigerant, causing this refrigerant to evaporate. A compressor furtherly increases the temperature. In the condenser, this heat is then transferred to the heating circuit of your home. Having passed the heating circuit, the vapour reaches an expansion vessel. As the name suggests, here the vapour expands – or decompresses –, cools down and ultimately liquifies: enabling the refrigerant to absorb environmental energy over and over again. This ingenious process allows the heat pump to turn air, groundwater, or geothermal heat into warmth – for you to enjoy within your four walls.

What are the considerations and expected costs of a heat pump?

Heat pumps are a great low-carbon heating solution that can also help contribute to lower heating bills. This impact can vary based on the existing efficiency measures in your home. For example, well-insulated homes will see greater energy savings. The Boiler Upgrade Scheme offers a grant of up to £7,500 towards the cost of replacing your gas boiler with a heat pump.

As with any type of heating system, cost is also dependant on the type of heat pump, overall output, and installation cost. Typically, air source heat pumps can cost between £7,000 and £13,000, water source at around £10,000, and ground source between £14,000 and £19,000.


Regardless of which type of heat pump is installed, the energy efficiency is similar, with 75% of the total energy coming directly from the existing heat source. The remaining 25% of energy is drawn from your home's electricity supply. This means that 75% of the energy you use to heat your home and hot water will come from a renewable source. Heat pumps can also be paired with pre-existing renewable technologies for greater efficiency.

Heat source

One of the key differences between the three types of heat pump is the heat source that they draw from. As the names suggest, this is drawn from the air, the ground or a water source. Which type of heat pump is most suitable for you may greatly depend on the amount of space or land you have available. We’ll look at this in more detail below.

Installation locations

For all heat pumps, the primary pump unit is located outside the home. The specific location will be dependant on the chosen energy source.

Some internal space is also required when looking to upgrade our heating system. This will likely include a cylinder, buffer, and hydraulic module. Ground source and water source heat pumps are often paired with our flexoTHERM internal unit.

Air source heat pumps

Air source heat pumps are the most common heat pumps in the UK. They have a great amount of flexibility for installation location and are often the easiest and quickest to install. The outdoor units can be installed on the ground, on a structurally stable balcony, or mounted on an exterior wall. Covers can also sometimes be used to disguise the outdoor units, particularly for projects and listed buildings where aesthetics are particularly important.

Ground source heat pumps

Ground source heat pumps require significantly more outdoor space, but this can be achieved either through boreholes or a ground array system. These typically offer a cleaner outdoor aesthetic than air source heat pumps. However, they can take longer to install and are only suitable for those with the required space available.

A ground array is created by burying horizontal collectors in the ground. These often require the property to have sufficient land available for installation. These collectors are installer approximately 1.2m below the surface. Borehole systems use vertically installed collectors and are typically dug around 100m deep.

The land being used for the heating collectors will also have to be accessible for the digging equipment.

Water source heat pumps

For the installation of a water source heat pump, the property ideally needs to be within 100m of a water source. Suitable water sources include lakes, rivers, ponds or streams.

The pipework required for a water source system is submerged, reducing the visual impact of the installation.

Don't forget to check if there is any planning permission required when installing a ground or water source heat pump.

Wondering if your home is suitable for a heat pump?

Before deciding what heat pump is the best choice for your home heating, there are some additional factors to consider, these include:

  • Home location

  • Internal and external space available

  • Home construction and insulation

  • Budget

Ready to start your heat pump journey?

Heat pump FAQs Time to clear up a few misunderstandings: 9 myths surrounding heat pumps.

  • 1. Heat pumps aren’t efficient

    They most certainly are! Given the right conditions, modern Vaillant heat pumps are extremely efficient. Up to 75% of the energy generated comes from ambient heat. Only the remainder is powered by electricity.

  • 2. Heat pumps cost a fortune, don’t they?

    Just a minute! It’s true that the initial costs for a heat pump are higher than for other heating systems. But with the Boiler Upgrade Scheme, offering grants of up to £7,500 in England and Wales, heat pumps are more affordable than you think.

  • 3. Heat pumps only work well with underfloor heating

    It’s true that heat pumps work particularly well with underfloor heating, which requires low flow temperatures thanks to a relatively large transfer area. But it’s by no means a must: heat pumps also work for heaters that need higher flow temperatures. Vaillant’s product portfolio has heat pumps that work for everyone.

  • 4. Heat pumps are only suitable for new buildings

    Vaillant heat pumps are designed with both new buildings as well as old in mind. They are an ideal solution for new constructions, which are built to be well insulated. But Vaillant also has heat pump systems that are designed to work in older buildings with radiators.

  • 5. Heat pumps take up so much space

    Vaillant heat pumps come in all shapes and sizes – and some heat pumps like the air source pump have both indoor and outdoor units. Sizes range from the height and width of a wardrobe (190 cm x 180 cm) to the size of a small dresser. You will certainly find one to fit.

  • 6. You need earplugs with heat pumps!

    Not with our heat pumps! Vaillant heat pumps are extremely quiet – including the air source heat pumps that have an outdoor unit. From a distance of three metres, you can expect a sound level of no more than 32dB – that’s hardly more than the rustling of leaves.

  • 7. Heat pumps aren’t reliable in winter

    Actually, heat pumps work reliably all year round. In fact, the outdoor unit of a Vaillant air source pump can work happily at an outside temperature of -20°C. And groundwater and ground source heat pumps are unaffected by winter weather since temperatures remains constant.

  • 8. Heat pump technology is still in its infancy

    In certain areas like Scandinavia, one of the most technically advanced regions when it comes to sustainable energy solutions, heat pumps have set the standard for heating technology.

    At Vaillant we have been recognised experts in heating systems for almost 150 years – and continually work to improve them. Our heat pumps are made in Europe to the highest.

  • 9. Heat pumps aren’t future safe

    Climate change and energy shortages make heat pumps THE renewable energy solution for today, tomorrow – and the future. A Vaillant heat pump is the optimal way, not only to reduce your carbon footprint, but to significantly keep heating bills to a minimum. And in combination with a solar system, you can be practically energy self-sufficient.