Air Source Heat Pumps Explained: How They Work

What Is an Air Source Heat Pump?

An air source heat pump is a low-carbon heating system that takes heat from outdoor air and transfers it into your home for space heating and hot water. In the UK, it is the most common type of domestic heat pump because it is cheaper and easier to install than ground source, and it can qualify for the £7,500 BUS grant subject to eligibility.

Energy Saving Trust says a typical air source heat pump costs around £11,000 to install, while MCS reported in August 2025 that there were 30,000 certified heat pump installations in the first six months of 2025. That scale matters because it shows air source heat pumps are no longer an edge-case technology for unusual homes.

For most homeowners, an air source heat pump is the practical version of the broader “heat pump” idea. It sits outside the house, uses electricity to move heat rather than burn fuel, and works best when the whole system is designed properly around the building.

If you want the wider national overview first, read our complete guide to heat pumps in the UK. If your next question is about funding, our BUS Grant complete guide covers that in full.

How Does an Air Source Heat Pump Work?

An air source heat pump works by absorbing low-grade heat from outside air, compressing a refrigerant to raise its temperature, and then transferring that heat into water for your radiators, underfloor heating, and hot water cylinder. The reason it can still work in winter is that outdoor air still contains usable heat energy even when it feels cold.

Energy Saving Trust says heat pumps can generate around three units of heat for every unit of electricity they use, which is why they are often described as roughly 300% efficient in broad terms. That efficiency advantage is the core reason air source heat pumps can compete with boilers despite electricity costing more per kWh than gas.

The process is straightforward:

1. The outdoor unit draws in air.
2. A refrigerant absorbs heat from that air.
3. The compressor raises the refrigerant temperature.
4. A heat exchanger transfers that heat into the home’s heating water.
5. The cycle repeats continuously.

This is also why system design matters. A heat pump is not just a replacement box for a boiler. It is a different way of heating the home, usually at lower flow temperatures and with steadier operation. That is why emitter sizing, controls, and hot water design matter just as much as the unit itself.

Why Are Air Source Heat Pumps So Efficient?

Air source heat pumps are efficient because they move heat rather than create it by combustion. In practical terms, the electricity powers the compressor and controls, but most of the delivered heat comes from the outdoor air, which is why the system can supply more heat energy than the electrical energy it consumes.

Energy Saving Trust says a heat pump can generate around three units of heat for every unit of electricity used. A modern gas boiler, by contrast, is normally around 90% efficient, which means it delivers less useful heat than the fuel energy you put into it.

Here is the basic comparison:

The important homeowner point is not the headline percentage on its own. It is what that means for real running costs. A strong seasonal performance factor can make an air source heat pump broadly competitive with gas or cheaper, especially if the system uses smart tariffs or solar to offset electricity demand.

For the running-cost side, read our heat pump running costs guide.

How Much Does an Air Source Heat Pump Cost?

In 2026, a typical air source heat pump costs around £11,000 before support, but real project prices often fall in a broader £10,500 to £14,000 range depending on your home and the supporting work needed. After the BUS grant, subject to eligibility, many straightforward air source projects land around £3,000 to £6,500 for the homeowner.

Energy Saving Trust uses around £11,000 as the benchmark cost for an air source heat pump installation. GOV.UK says the Boiler Upgrade Scheme can contribute £7,500 toward an eligible air source heat pump, which is why this technology has become much more accessible than many homeowners assume.

Typical cost drivers include:

1. Property size and heat loss.
2. Radiator suitability.
3. Cylinder installation if replacing a combi boiler.
4. Pipework, controls, and commissioning.
5. Site complexity and unit siting.

That means the “air source heat pump price” is never just the cost of the outdoor unit. The whole point of the survey is to understand the system cost, not only the hardware cost.

If you want a deeper breakdown, read heat pump cost UK 2026 or start with our BUS Grant survey page.

Is an Air Source Heat Pump Suitable for Your Home?

Many UK homes are suitable for an air source heat pump, but the right answer depends on outdoor unit siting, hot water cylinder space, emitter sizing, and whether the home can be designed sensibly for low-temperature heating. In practical terms, the biggest issues are usually layout and system design rather than the age of the building alone.

Nesta reported in February 2026 that 80% to 90% of UK homes already have enough insulation to run a heat pump. That matters because it shows many homes are closer to “air-source ready” than the market used to think, but it does not remove the need for a proper survey.

The most important checks are:

Many semis, terraces, bungalows, and detached homes in London and Surrey can work very well with air source heat pumps. Flats are more constrained, but they are not automatically impossible. The right conclusion has to come from a real property assessment.

Read is your home suitable for a heat pump? and heat pump planning permission if you want to go deeper.

How Electromatic Can Help

If you want to know whether an air source heat pump is right for your own home, Electromatic can assess the property, explain the likely system scope, and show what the project may cost before and after the BUS grant if you qualify. That is more useful than relying on generic ASHP claims because the success of the system depends on the property, not just the product brochure.

Energy Saving Trust’s benchmark for a typical air source heat pump is around £11,000, and GOV.UK says eligible projects can receive £7,500 through the BUS grant. Electromatic works under MCS certification via our accredited umbrella partner, so we can design compliant projects and guide homeowners through the funding and survey process correctly.

What we can help with:

1. Free survey for suitable homes in London, Surrey, and nearby TW areas.
2. ASHP design, emitter review, and hot water planning.
3. BUS grant handling, subject to eligibility.
4. Advice on whether solar should be part of the same plan.
5. A local, property-specific view rather than generic sales messaging.

Book your free home survey →

Call us: 07718 059 284 | Email: admin@electromatic.uk

Frequently Asked Questions

What is an air source heat pump in simple terms?

It is a system that takes heat from outside air and moves it into your home for heating and hot water. It uses electricity to run the compressor, but most of the heat delivered comes from the outdoor air itself.

Is an air source heat pump the same as a normal heat pump?

It is the most common type of domestic heat pump in the UK. When most homeowners say “heat pump”, they usually mean an air source system rather than ground source.

How much does an air source heat pump cost in the UK?

Energy Saving Trust says a typical air source heat pump costs around £11,000 before grant support. After the BUS grant, subject to eligibility, many homes pay several thousand pounds rather than the full benchmark amount.

Does an air source heat pump work in winter?

Yes. It can still extract useful heat from outdoor air in winter, although the system’s performance is usually better in milder conditions than on the coldest days.

Is an air source heat pump worth it?

For many homeowners, yes, especially if the boiler is ageing and the property can support a well-designed low-temperature system. The strongest cases are homes that can also use grant support, smart tariffs, or solar over time.

The information in this article is for general guidance only and does not constitute financial, legal, or technical advice. Energy savings estimates are based on typical UK household data from the Energy Saving Trust and Ofgem (April 2026 price cap). Actual savings depend on your property type, insulation levels, energy usage patterns, and electricity tariff. The Boiler Upgrade Scheme (BUS) grant of £7,500 is subject to eligibility criteria set by Ofgem — not all properties qualify. Electromatic M&E Ltd operates under MCS certification via an accredited umbrella partner. All installations comply with Building Regulations Part L and MCS standards. E&OE.

Written by Electromatic M&E Ltd — ASHP & Solar installer, London & Surrey (electromatic.uk)

Last updated: April 2026 | Electromatic M&E Ltd, Company No. 13837345