Heat Pumps

How do heat pumps work?

Heat pumps are a low carbon heating option and may help reduce your energy bills.

These pumps capture heat from outside, move it into your home and transfer it to a heating circuit. It is then distributed around your home via radiators, underfloor heating or warm air ducts.

The main difference between a boiler and a heat pump is flow temperature, which is the temperature of the water in your radiators. For a heat pump this is around 30°C to 50°C. In a typical boiler, it's around 60°C to 80°C.

There are different types of heat pumps that work in different ways.

Air source heat pumps

Air source heat pumps use an outside unit to extract heat from the outside air. The unit uses a large fan to draw air over a heat exchanger.

Find out more about air source heat pumps from the Energy Saving Trust.

Ground source heat pumps

Ground source heat pumps extract heat from a ground loop and transfer it to a heating circuit.

The ground loop, usually a high-density polyethylene pipe, is either:

buried horizontally in a trench about 1.5 to 2 metres deep
sunk into a vertical borehole

The heat pump unit draws thermal energy from fluid (called brine), which circulated through the ground loop.

Find out more about ground source heat pumps from the Energy Saving Trust.

Our case study 22 includes the installation of a ground source heat pump at a rural cottage in Braemar.

Water source heat pumps

A water source system is much the same as a ground source heat pump, but instead of being buried in the ground, the collector loop is sunk into a watercourse or static body of water. Ground source is by far the more common.

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Can a heat pump work for my traditional building?

Can a heat pump work for my traditional building?

To provide the same heat to a room as a typical boiler, a heat pump needs more radiators, bigger radiators, or a combination.

Underfloor heating is ideal for a heat pump because it turns the entire floor surface into a heat emitter.

If you need to alter radiators and pipework, there could be significant disruption and damage to your home.

Air source heat pump units also have a visual impact. Once a ground or water source system is installed, you won't see it. However, the installation of a collector loop can involve substantial groundworks.

Ground or water source systems usually need considerably more indoor space due to bulkier plant equipment.

A heat pump is unlikely to be a good option if your home isn't well insulated. The system would struggle to deliver enough heat and still be efficient.

Improve your home's insulation first or consider other renewable energy options.

There is very little maintenance needed when it comes to heat pumps. Yet, it's wise to make sure vegetation doesn’t build up around an Air Source Heat Pump as this will obstruct the flow of fresh air to the unit and impact efficiency.

Typically, a heat pump will require only a visual inspection by a qualified individual once every year to three years, but check with your installer.

Which type of heat pump is best?

If you don't have enough land, scope for a borehole, or suitable watercourse, then ground/water source heat pumps won't be suitable for your home.

If air source and ground/water source are all options for you, consider the costs. While ground or water source heat pumps can have lower running costs over the longer term, they have a higher installation cost.

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How do heat pumps work?

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Costs and savings

Costs and savings

While installation costs can be high, heat pumps can be worth the money. This is especially true if your property has no access to the mains gas network.

Ground or water source heat pumps are significantly more expensive to install than air source heat pumps, but the benefit will be higher efficiency.

Their lower running costs can add up to considerable savings over the longer term.

Discover how much energy you can generate and calculate potential savings with the Energy Saving Trust’s Home Renewables Selector.

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Can a heat pump work for my traditional building?