Air Source Heat Pump
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Definition
An air source heat pump is a low-carbon heating system made up of an outdoor unit and an indoor hot water cylinder. They use electricity to move heat from the air into your home, warming radiators, underfloor heating, and hot water.
Unlike gas boilers that burn fuel, air source heat pumps simply move existing heat, making them a cleaner, smarter way to heat your home.
How does an air source heat pump work?
Air source heat pumps don’t generate heat - they just move it. By pulling existing warmth from the air outside and bringing it into your home, they keep you cosy in winter and cool in summer. The way heat pumps move air is what makes them so smart. It’s this clever tech that puts air source heat pumps at the forefront of low-carbon heating - cutting emissions and helping you go greener without compromising on comfort. Take a look at how it works below.
Green Impact
Air source heat pumps are impressively clever little machines. They use a small amount of electricity to capture natural warmth from the air outside and amplify it to heat your home. In fact, air source heat pumps can deliver several units of heat for each unit of electricity. For every 1 kWh of electricity you put in, you could get an average of up to 3.3 KWh heat out. For Octopus customers with low temperature heat pumps, the typical seasonal coefficient is 330%, so up to 4x more efficient than the typical gas boiler with an 85% efficiency on our standard variable tariff.
What does that mean for you (and the planet)?
Right away, you'll be using around a quarter of the carbon emissions of a traditional boiler. And as the UK energy grid goes fully green, your heating could eventually become zero carbon.
Since they’re so efficient, air source heat pumps need far less renewable energy than other low-carbon options like electric boilers, and their flexibility means they can even help ease pressure on the grid during peak times.
Our customers are leading the switch to low-carbon heating.
We asked 1,607 customers who had a heat pump installed between April and December 2024 about their experience after their first winter. 86% rated their overall satisfaction between 7 and 10.
93% say it's as comfortable or more comfortable than their previous boiler.
87% say it costs the same or less to run.
83% say it's the same noise level or quieter.
90% say it's just as easy or easier to maintain.
"Right now, our world relies on stealing energy and natural resources that we can’t give back. If you want to continue to be a part of the natural world, you have to act like nature. With heat pumps, you don’t have to burn anything, you don’t have to steal anything - we’re mimicking nature. Even when it’s cold outside, we can take some of that energy and produce something with it." Peter, heat pump expert
PROS
A heat pump is up to 4x more efficient and typically last longer than a gas boiler.
Heat pumps give reliable, consistent heating and hot water.
Air source heat pumps reduce your carbon emissions by around 80%.
Cosy heat pump customers on the Cosy Octopus tariff saved an average of £224 last yer compared to using a gas boiler running at 85% efficiency on our standard variable tariff.
CONS
You’ll need a bit of outdoor space for the unit but it's compact by design, with a footprint of just 1.85m × 1.35m.
May require upgrades to your home, like better insulation or larger radiators.
Cosy Heat Pump - Octopus Own Air Source Heat Pump Brand
Cosy is a smart, energy-efficient heat pump setup designed to keep your home warm and your bills low,. It's pretty much the most affordable full heat pump package available in the UK at the moment. What's included:
Air Source Heat Pump System
That good-looking unit down there? It blends right into your garden vibes, and it’s not just a pretty face, either. This one’s got serious smarts.
Installation with Cosy Turbo or Eco
Cosy Turbo installs faster using your existing radiators, while Cosy Eco takes longer but runs more efficiently with upgraded radiators for lower long-term energy bills.
Smart Heating Controls (Cosy Control)
Think of it like a smart thermostat, it does scheduling, zoning, and app control to make heating more efficient and convenient.
Integration with Cosy Octopus Tariff
A flexible heat pump electricity tariff that charges less when energy is greener and cheaper, helping you save money.
Ongoing Optimisations for Comfort and Savings
The system learns your heating habits and adjusts to keep things comfortable without wasting energy.
Heat Pump Grants & Finance Available
There are a range of grants and financing options to make heat pump installation more affordable for UK homeowners. Here's a summary of what's available:
Boiler Upgrade Scheme (BUS): If your home uses oil or LPG heating, you could get up to £9,000 towards an air source or ground source heat pump. The government has increased the Boiler Upgrade Scheme grant from £7,500 to £9,000 for eligible off-gas homes in England and Wales, making the switch to a heat pump more affordable than ever.
Energy Company Obligation (ECO) Scheme: Eligible households may receive free or discounted home energy upgrades, including heat pumps, insulation, and solar panels. Eligibility is based on factors like income, benefits received, and property type.
Flexible financing with Novuna. Flexible financing options are available to help spread the cost of your heat pump installation. You can choose from a range of repayment plans to suit your budget, subject to eligibility.
£2000 cashback scheme: You could claim up to £2,000 cashback from your bank when you install a heat pump through Octopus Energy
Check it Out!
Knowledge is Power
Brains Behind the Heat
We Know Heat Pumps Inside Out (Literally)
Heated Debates? Settle Them Here
Heat Pump FAQ Page
Heat Pump Reviews
Customers Review their Cosy Heat Pump ⭐️⭐️⭐️⭐️⭐️
Cosy heat pump customers on the Cosy Octopus tariff saved an average of £200 last year compared to using a gas boiler running at 85% efficiency on our standard variable tariff
This figure is based on the actual energy consumption of all Cosy heat pump customers on a Cosy Octopus tariff between 1 July 2025 and 1 July 2026, using tariff rates at the time.
We compared this to the cost of producing the same amount of heat with a gas boiler operating at 85% efficiency, priced using our Flexible Octopus (standard variable) tariff at the same time.
Savings from gas standing charges were included only for customers who had fully removed their gas supply (less than 3% of customers). Actual savings vary depending on system design, tariff choice, home insulation, and energy use.
Our typical heat pump price is £4,459, which is lower than the national average of £5,600
This is the median post-survey price from all of our heat pump quotes after the £7,500 Boiler Upgrade Scheme has been applied, between 01/09/2025 and 28/02/2026. The national average is taken from the Boiler Upgrade Scheme statistics: April 2026 – median cost of installation Q4 2025.
Cut carbon emissions by 82% with a heat pump
This is the typical reduction in heating carbon emissions using an electric powered heat pump compared to a gas boiler.
The carbon breakdown
Gas CO2 (tonnes per year) - 2.42
Electricity CO2 (tonnes per year) - 0.43
Carbon saving (tonnes per year) - 1.99
Data sources and assumptions
Gas Energy Usage (kWh) 11500 (Ofgem medium use gas usage (Jun 2026))
Heat Pump Efficiency 312% (typical seasonal coefficient of performance from a fleet of Octopus high temperature heat pumps)
Gas Boiler Efficiency 85% (The typical gas boiler efficiency from a BEIS study)
Gas fuel emissions of (gCO2/kWh) 210 (SAP 10.2)
Electricity fuel emissions of (gCO2/kWh) 136 (SAP 10.2)
Based on these sources, heat pumps typically produce lower operational emissions when heating the home than gas boilers.
For more information, explore our Octopus Cosy heat pump fleet performance dashboard.
We're the largest heat pump installer on the Boiler Upgrade Scheme
Based on Octopus benchmarking against Ofgem reports from 2024, and we've continued to grow since.
Our customers love their heat pumps!
- 93% of people say it's the same or more comfortable than their previous boiler
- 87% say it costs the same to run or less
- 83% say it's the same noise or less than the previous boiler
- 90% say it's just as easy or easier to maintain
We survey all our heat pump customers 3 months post-installation to see how they find their heat pump compared to their previous gas boiler. Survey results are taken from a sample of 2,837 customers:
Comfort: 93% of people say it is the same or more comfortable than their previous boiler.
Running Costs: 87% say it costs the same to run or less.
Noise: 83% say it is the same noise or less than the previous boiler.
Maintenance: 90% say it is just as easy or easier to maintain.
A heat pump is around 4x more efficient than a gas boiler
Heat pumps don't generate heat by burning fuel. Instead, they transfer existing heat into your home. This means they can deliver multiple units of heat for each unit of electricity used.
Based on performance data from a fleet of installed Octopus Cosy heat pumps, typical real-world seasonal performance (SPF or SCOP) is around 3.6. This means around 3–4 kWh of heat is delivered for every 1 kWh of electricity used (an effective efficiency of 300–400%). By comparison, typical UK domestic gas boilers operate at around 85% efficiency, delivering approximately 0.85 kWh of heat per 1 kWh of gas used. On this basis, a heat pump can be around 4× more efficient than a typical gas boiler.
All our heat pumps are independently tested by the Building Research Establishment (BRE), with SCOP values published on the Microgeneration Certification Scheme (MCS) product database. Actual efficiency will vary depending on the property, system design, and usage. For more information, explore our Octopus Cosy heat pump fleet performance dashboard.
The UK's most awarded energy supplier
We've won more awards for customer service than anyone else.
Heat pumps give reliable, consistent heating and hot water
The heat pump user survey report by Nesta from May 2023 summarises that "users are highly satisfied with their heat pumps". It states: "People living in England, Scotland and Wales who own their home and use a heat pump to heat it are satisfied that heat pumps are safe, reliable, quiet heat sources that are effective for space heating and producing hot water." Find the full report here.
The Cosy heat pump is quiet
Heat pump sound power levels are verified by an independent, third-party laboratory as part of the testing process for inclusion on the MCS product database. The laboratory verifies the sound power on the A-weighted decibel curve, as A-weighting closely aligns to how humans perceive "loudness".
All heat pumps are measured using EN14511 standards to ensure uniformity across manufacturers and models. Our Cosy 6 heat pump has a verified sound power level lower than many other heat pumps of the same capacity.
Heat pump heating makes the air healthier in your home
Homes with a heat pump emit far less harmful nitrous oxide (NOx) emissions than those with gas boilers and cookers, significantly reducing asthma and other respiratory illnesses. According to the Sustainable Markets Initiative Cleantech Homes report.
A heat pump can add thousands to your property value
Analysis by the Department of Land Economy at the University of Cambridge suggests a 16% value uplift for new-build homes with enough solar and battery storage to eliminate energy bills. A further study of over five million existing properties indicates a 2-3% value increase for existing homes with solar panels or heat pumps (versus like-for-like gas-heated homes), according to the Sustainable Markets Initiative: Cleantech Homes report, 2024.
As of April 2025, the average house price in the UK is £265,497 according to the Land Registry. Therefore, a 2-3% value increase for an average house priced at £265,497 would be between £5,310 and £7,965.
Heat pumps typically last longer than gas boilers
The expected lifespan of a typical gas boiler is 10–15 years. A heat pump typically has a lifespan of 15–20 years, with UK government research indicating an average of around 20 years. Manufacturer Daikin reports similar ranges. Actual lifespan depends on factors such as installation quality, maintenance, usage patterns, and operating conditions.