Air source heat pumps are becoming increasingly popular, particularly in new-build houses. They save energy and money, but how exactly do they work?
If you’re looking to buy a new house that comes with an air source heat pump, or install one where you currently live, you’ve probably got questions. Is it worth the money? Is it suitable for your home?
Heat pumps are a great way to invest in greener energy, and the good news is air source heat pumps are significantly cheaper than ground source heat pumps.
We’ll delve into everything about air source heat pumps (ASHPs), how they work, how you can save money, what installation is like, and whether it’s the right choice for you.
Quickfire Q&A:
What is an air source heat pump?
An air source heat pump is a low-carbon alternative to heating your home by taking heat from the external air. They work all year round, even when it’s cold outside.
ASHPs power central heating via radiators or underfloor heating, and can also provide hot water in your home. Using electricity instead of gas at a high efficiency (around 300%, compared to a new gas boiler which runs at 90%) means they are much more eco-friendly than most other heating systems.
The heat pump itself is an unobtrusive device that sits just outside your home, running at about 50dB (which is the equivalent of an average fridge hum).
So, how does it work?
Air source heat pumps take the existing heat from the air outside, drawing it in via the fan. This heat is turned into a liquid refrigerant.
The pump uses electricity to compress this liquid into gas and increase its temperature, before it condenses back to a liquid.
This heated liquid is sent to your radiators, underfloor heating, and hot water cylinder.
Using existing heat from the air makes ASHPs a low-carbon alternative. The heat produced from the pump is greater than the electricity used to compress the air and turn it into heated liquid. For every unit of electricity they use, they produce three to four units of heat, making it around 300% efficient.
Air source heat pumps work even in winter (although not as efficiently), as there is always heat energy in the air, even below freezing. The temperature would have to get to -273℃ to have no heat energy whatsoever, which is pretty unlikely in the UK.
Air source heat pumps vs ground source heat pumps
There are two main types of heat pumps: air source and ground source.
As the name suggests, ground source heat pumps take heat from the ground. This temperature is much more consistent year-round than the heat from the air, making it a more efficient system.
Ground source heat pumps run at around 400% efficiency, meaning that for every unit of electricity used, they produce four units of heat.
Taking heat from the ground means you need to have pipes installed, which can be an intrusive process. The cost of ground source heat pumps range from £28,000 to £49,000, making it unaffordable for many people.
Air source heat pumps are more accessible, as they cost significantly less and require less ground space for installation.
How much money can you save?
The estimated savings of an air source heat pump versus a gas or LPG boiler are between £300 and £600 a year. You’ll see bigger savings if you’re replacing electric storage heaters or coal systems.
So, are heat pumps worth it? These figures depend on factors like how old your house is, insulation efficiency, your current heating system, the size of the home, and how much energy you use.
Not all homes can benefit from an ASHP, and the less efficient your home is, the fewer savings you’ll make. Older homes with poor loft insulation, single glazing, and a low rating for energy efficiency won’t see a good return on investment.
However, you’ll often find new-build homes come with an ASHP already installed. While this inevitably increases the cost of the property, you might find it saves you money over time if it’s a well-insulated, well-built home.
Gas: -£40 to £260
Electric: £700 to £1,200
Oil: -£220 to £65
LPG: £270 to £700
Coal: ~£700
Yearly savings based on figures from Energy Savings Trust. Range represents new versus old systems.
For newer, well-insulated homes, installing an air source heat pump can translate to great savings over time. You’ll be able to enjoy long-term energy bill stability as well as a sustainable way to heat your home.
Homes with existing solar panels can reap the most benefits from an air source heat pump. Heat pumps need electricity to work, so if you’re able to provide this electricity using solar energy, you’ll see a significant reduction in your bills.
What’s installation like?
Air source heat pump installation cost is between £7,000 and £13,000 with the average cost at around £11,000.
Installation costs depend on the size of the heat pump, the size of your property, and how old or new your home is.
You might also need to upgrade your radiators or add insulation to get the best efficiency, which affects the overall installation cost.
If you’re replacing your current radiators, you could consider underfloor heating, which works especially well with heat pumps. Using a larger surface area to gently heat your home, it’s more efficient at distributing the heat at the lower temperatures heat pumps produce.
Installing an ASHP takes around three to eight days and requires some outside space for the pump itself and inside space for the water storage tank.
It’s significantly less intrusive than the installation process for a ground source heat pump. In the majority of cases, you don’t require planning permission.
Tip: Choose an MCS-certified installer, who can recommend the best type of heat pump for your property and help you access government grants (see next section).
If your ASHP costs £11,000 to install and saves you £600 a year, it would take just over 18 years to pay for itself. If you’re eligible for the full £7,500 boiler upgrade grant, it’ll pay for itself in under six years.
Can you get a government grant?
The good news is, you can get a good chunk of free money towards your eco-friendly home upgrade. If you’re replacing a fossil fuel heating system with a heat pump, the UK government offers up to £7,500 to help cover the costs.
In England and Wales, the Boiler Upgrade Scheme offers up to £7,500 for replacing a gas or oil boiler with a heat pump.
In Scotland, you can claim funding of up to £7,500 through The Home Energy Scotland Grant and Loan Scheme which combines grants and interest-free loans.
You’re likely eligible if:
- You own your home
- Your property has a valid Energy Performance Certificate (EPC)
- The heat pump meets minimum efficiency standards (your installer will confirm this)
- Installation takes place within 120 days of applying for the grant
You’re not eligible if:
- You live in a new-build home
- You’re in social housing
- You’re installing a hybrid system (gas boiler + heat pump)
- You’ve already received a grant for replacing your heating system
Tip: you can apply for a grant through an MSC-certified installer, who can make sure you meet all the requirements to secure the money.
Green mortgages & loans
If you’re not eligible for a government grant or you want some additional funding, green mortgages or home energy loans could be your next step.
Heat pumps are seen as making an energy-efficient improvement to your home, and there are two ways to apply for extra funding.
1. You’re in the process of buying a home and want to install a heat pump
Some UK lenders will offer small reductions or preferential rates on their mortgages. These rates are usually between 0.1% and 0.15% lower than standard. Lenders that offer this include Barclays, Natwest, Nationwide, Coutts, and Danske Bank.
2. You own your home and want additional funding
Select banks will offer loans and funding to existing customers looking to make energy-efficient home upgrades (heat pumps, solar panels, insulation). These rates are often much more attractive than personal loan rates (some can even be interest-free), so check with your current mortgage provider to see what they offer. Lenders that offer this include Nationwide, Virgin Money, Ecology, and Santander.
Tip: houses with a high EPC rating are the most likely to get green mortgages or home energy loans.
Pros and cons of an air source heat pump
We’ve covered a lot of information, so let’s go over the pros and cons of ASHPs. They’re still a big investment, so it’s a good idea to figure out whether or not it’s the right choice for you and your home.
Pro | Con |
|---|---|
Reduces bills by £300–£600 a year | Not suitable for all homes, particularly older ones |
Uses electricity to run | Need indoor and outdoor space for installation |
Unobtrusive design | Can be expensive to install |
Heats home and water | May require new radiators or upgraded water cylinder |
Reduces carbon usage by ~13% a year | Less efficient in winter |
Efficiency of 300%+ | Efficiency depends on insulation quality |
Optimal savings with solar panels | Cell |
Works well with underfloor heating | Cell |
Eligible for government grant | Cell |
Eligible for green mortgages/loans | Cell |
Air source heat pump FAQs
Still got questions about how ASHPs work and if they’re right for you? We’ve got you covered.
Q. Are air source heat pumps noisy?
A. No, they run at around 50 decibels, which is the equivalent of the average fridge hum.
Q. Do they work in winter?
A. Yes, although less efficiently. There is always heat in the air, even when the weather is freezing.
Q. Do I need new radiators?
A. Possibly. ASHPs use much lower temperatures compared to gas boilers, so they work best with large or low-flow radiators. If your home has compact, inefficient radiators they might need replacing. Underfloor heating systems are the ideal way to heat your home with ASHPs, although not required.
Q. How long do they last?
A. An air source heat pump will usually last 15–20 years, or sometimes longer. Keep your heat pump in good condition by clearing any debris around it and scheduling in annual services.
Q. Can I use one in a flat?
A. Yes, although it’s much less common. You’ll need outdoor space for the pump and indoor space for a cylinder. You can opt for a compact ASHP for smaller spaces.
Q. Is it expensive to run an air source heat pump?
A. It can be. Heat pumps use electricity, which is currently more expensive than gas and oil. However, they are much more efficient than even a new gas boiler, so if electricity costs come down, you’ll see a big improvement in savings.
Q. What is the downside of an ASHP?
A. The upfront cost of installing a heat pump is usually the main deterrent. While it’s around 300% efficient, it doesn’t work as well in colder temperatures.
Pump up the savings
An air source heat pump is a great choice for those looking for a low-carbon alternative to heat their home. Buying a home with an ASHP already installed could be a big plus.
If your home meets the requirements, you could start saving money and energy every single year. With government grants, green mortgages, and energy home loans, an ASHP could be an affordable option for you.
Of course, ASHPs aren’t right for every home, so make sure you do your research to see if the figures make sense for you.
Do you have any more questions about air source heat pumps? Or have you recently installed one and have feedback on your experience? Let us know in the comments below.