How does an Air Source Heat Pump work

Heat from the air is absorbed at low temperature into a fluid. This fluid then passes through a compressor where its temperature is increased, and transfers its higher temperature heat to the heating and hot water circuits of the house.

The air source heat pump (ASHP) complies with government guidelines and local authority building regulations, reduces carbon emissions. Turn to the green side today.

Reduce your monthly bills and claim the Renewable Heat Incentive Scheme Payments (RHI) with low maintenance and a straightforward install for the majority of properties.


How do air source heat pumps work?

An air source heat pump absorbs heat from the air outside into a fluid. This is fed through a compressor to increase its temperature, and transferred to the indoor heating and hot water distribution network. Essentially, air source heat pumps work like a refrigerator in reverse. The outside fan unit is usually positioned on an external wall.

How much do air source heat pumps cost to install?

Air source heat pump installations usually cost between £7,500 and £12,500, depending on the size and power of the heat pump, how much hot water storage you require and whether you want the heat pump to have additional features, such as remote web-connected control.

Existing properties might need insulation upgrades to meet Ofgem RHI regulations, which would of course add to the overall cost of a project. But for the air source heat pump purchase and installation alone, the above cost estimate is usually accurate.

How can I finance an air source heat pump

The Renewable Heat Incentive (RHI) scheme is available to homeowners in England, Wales, and Scotland. This pays on a quarterly basis, with tariffs based on your system and the amount of renewable energy it generates. Download our guide to the RHI here.

In Scotland, residents benefit from the Home Energy Scotland Loan. This offers an interest-free loan to cover part of a renewable heat installation. It won’t always cover the whole outlay, but it does provide very useful assistance.

In the rest of the UK, the Assignment of Rights (AoR) allows property owners to choose a nominated investor to fund their air source heat pump installation. The investor then claims the client’s RHI payments as a form of repayment.

How much space do I need for an air source heat pump

Heat pumps require a bit more space than a traditional wall-hung boiler system. The hot water cylinder is often located next to the system, rather than elsewhere in an airing cupboard. It’s important to plan a dedicated area (plant room) for the equipment. Possible solutions for a plant room are utility rooms, garages, basements, or possibly a detached outbuilding.

For the fan unit itself, you need adequate space on the outside of an external wall. This must be free from nearby obstacles and be located at least one metre from the property boundary (as per official planning rules). The size of the box depends on the size of the system and the manufacturer. However, most domestic air source heat pump units don’t exceed 1 x 1.5 metres, and are less than 0.5 metres in depth. Speak to one of our advisors about your options.

What are the running costs of an air source heat pump

Running costs depend on the size of the property and system. The typical UK home requires about 12,000 kW of heat annually. An air source heat pump may create 3 kW of heat for each 1 kW of electricity it consumes. As a result, it will use 4,000 kW to fulfil the demand. As a rough example, with electricity priced at £0.13 per unit, annual running costs will be £520.

This is by no means a hard and fast rule. If you get electricity from your own renewable source, such as a solar PV installation, the running costs will be eliminated. Speak to one of our experts for more clarity about your savings from an air source heat pump.

Can I use radiators with an air source heat pump

Yes, but radiators must be adequately-sized. Air source heat pumps work best with underfloor heating, because of the ability to deliver constant low-grade heat. Underfloor heating will work well with flow temperatures as low as 35 degrees celsius. However, if your radiators are large enough to cater for a low flow temperature, they will be suitable for your air source heat pump.

Some clients have underfloor heating on the lower floors, and large radiators on upper floors of the property. It’s about ensuring that you have the right heat distribution system in place to benefit from the efficient operation of an air source heat pump. Contact us for more information.

Are air source heat pumps noisy?

No, they are quiet systems. This reputation is undeserved. Modern air source heat pumps are not noisy if they are installed correctly. Because it has working parts, the fan unit may reach 40-60 decibels from a metre away, but this isn’t common. Even so, this level of noise is not disruptive and decreases considerably as you move further away from the unit.

For detailed information, read our article: Are heat pumps noisy?

How efficient is an air source heat pump?

Air source heat pumps are between 200% and 400% efficient. This means they produce 2-4 times the amount of heat compared to the energy they use. This might change slightly during colder months, but the heat pump will still be able to power heating and hot water efficiently. For more information about efficiency variations, get in touch with Smart Renewable Heat.

Can an air source heat pump be installed on an old house

Yes, provided you have a suitable heat distribution system installed. In order to qualify for the RHI scheme, you must have an energy efficient building. Therefore, you may need to complete upgrades on loft and cavity wall insulation to meet regulations. Read the Ofgem information for more guidance on installing an air source heat pump in an old property.

How can I maintain and service an air source heat pump

Air source heat pumps need a basic annual service, and we can help with this. Our engineers will ensure that your ASHP is working to optimal efficiency, giving it the best lifespan possible.

How long will an air source heat pump work for

Typically, these systems last for 15-20 years. However, they have been known to work for longer. With annual servicing and good care, an air source heat pump is an investment that continues to deliver returns over decades.

Do I need planning permission for an air source heat pump?

Air source heat pumps don’t usually need planning permission. They are considered in England, Wales, and Scotland to be a permitted development. However, this changes if the property is listed, or if the property is in a protected area. It doesn’t mean that it’s impossible, but you will need to check with the local authorities to see what can be done.

Can I use an air source heat pump during winter?

Of course, yes. Air source heat pumps can still deliver heat to your home when outdoor temperatures are as low as minus 15-20 degrees celsius. There might be some slight variation in efficiency and the air source heat pump will need to work harder, but they are designed to work in all seasons throughout the year.

What a refreshing change. Everything went as planned and explained to me. All completed in one day too!. Highly recommended

All good. Engineers turned up on time. Were very polite and understanding. They cleaned up after themselves! I can’t comment on the systems running to its full potential as yet because it has been mild, but so far so good. V happy. Thank you.

We had our Air Source Heat Pump fitted by Project Heating. I was talked through everything before it was fitted. Engineers were very professional, clean and tidy. My house if now lovely and warm. Would highly recommend.

Engineers were clean and tidy and turned up when they said they would. Very quick and talked me through how to run my system. Really happy.

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