While installing an air source heat pump, much like any other type of heating system isn't a job for your DIY list, what can you expect from the process?
It will of course vary, depending on if you're installing an air source heat pump as part of a new self build project, or if you're upgrading to one as part of a home renovation. However, in either case, there are key elements involved that can help you ensure you're prepared once it's time for installation to take place.
In this handy guide, energy expert David Hilton, along with additional heat pump experts outline everything you need to know about installing an air source heat pump, including how to find an installer and how long you can expect the process to take.
Who can install a heat pump?
It's important to stress that you need a heat pump specialist for installing an air source heat pump, for a number of different reasons, not least of all the technical knowledge on how heat pumps work.
An installer requires a fundamental understanding of low temperature heating systems, vapour compression cycle principles, weather compensation controls and the behaviour characteristics of the heat pump controls in order to specify the system correctly, and commission the operating conditions of the heat pump.
Air source heat pump systems will also have electrical connections that need to be made by suitably qualified electricians, as well as plumbing circuits that need to be made by unvented system qualified and experienced installers.
All of the working settings must be set up correctly, or the technology may not achieve the desired results or alternatively could use a lot more electricity. Given the low flow temperatures associated with ASHP systems the emitters (usually radiators or underfloor heating) also need to be specifically sized and controlled to optimise the system.
So how do you know your installer will be qualified enough to have this knowledge? By only using an accredited Microgeneration Certification scheme (MCS) installer .
"MCS certification acts as the primary quality mark, ensuring installations meet high safety and performance standards," explains TJ Root, heat pump program director at Octopus Energy. But, it's not just about safety and knowledge, as it could also impact how much you pay for your heat pump costs.
"It is mandatory for accessing government funding like the Boiler Upgrade Scheme (BUS),"he adds, "and it provides consumers with robust insurance-backed warranties, and guarantees that installers are technically competent.
"So while a very technically-minded and skilled homeowner might be able to install their own heat pump, it would be unlikely that they’d be able access the generous support available from the BUS as a DIYer," says TJ.
"It’s also important to verify the installer is a member of HIES or RECC consumer codes. This protects your deposit and provides an insurance-backed guarantee," he adds.
TJ Root is the Heat Pump Program Director at Octopus Energy, where he oversees the design, development, and delivery of the Cosy series of air-source heat pumps across the UK and select global markets. He previously worked in strategy consulting and served as a special operations aviator in the US Army, with degrees in economics & mechanical engineering from West Point and an MBA from the Harvard Business School.
How can I find an installer?
In general, working with a reputable air source heat pump company will provide you with potential installers, as the experts explain.
"As a first port of call, I recommend visiting one of Daikin’s Sustainable Home Centres, a network of regional hubs across the UK, which allow homeowners to familiarise themselves with Daikin’s air source heat pump technology and the benefits of sustainable, low-carbon, home heating," suggests Hamid Salimi, residential product manager at Daikin UK.
"The centres support potential customers by providing expertise on a wide range of products offering a place to sit down with experts to discuss and agree on the best solution for their home, before being partnered with a trusted local installer."
Richie Atkinson, head of future energy homes at E.ON Next, agrees on the benefits of a complete start to finish service. “When you’re building or upgrading a home, having experienced people involved early who can look at how everything fits together can be a real help.
"We focus on understanding the property – things like home insulation, existing heating and how the space will be used – so the heat pump is suited to the home rather than forcing changes later.
"Using MCS‑accredited installers helps ensure the system is properly designed and installed," he continues, "and we take time at the end to explain how it works so the household feels comfortable living with it.”
Octopus also works in a similiar way, offering a Trusted Partners programme. Launched in 2024, the programme was created to help ramp up the deployment of heat pumps and solar across the UK by partnering with trusted local installers to deliver clean tech installations that Octopus can’t immediately carry out – whether due to geography or high demand.
The best route to market for air source heat pump installations, as the experts suggest is to get a supply and install contract. That way the chain of custody is complete and there is full continuity from specification right through to commissioning. It is possible to purchase the system components separately but you would need to be sure that they are all compatible with each other.
Hamid has worked with Daikin for over 13 years in various roles such as product applications, HVAC design and currently as a Product Manager leading a team of product specialists covering all aspects of residential renewable heating.
As E.ON Next’s Head of Future Homes, Richie Atkinson and his team are helping to transform homes up and down the country, improve people’s comfort, lower energy bills and make homes more sustainable and fit for the future. Richie has worked at E.ON for over 13 years and is now responsible for bringing greener, cleaner and more sustainable solutions into people’s homes.
What do I need in place prior to installation?
The earlier in the process that you can appoint an air source heat pump installer the better. There are lots of components that need to be installed, and there are also other trades that need to also have their products installed to do it.
If you are considering one for a self build home, "in new builds, heat pump planning works best when included at the design stage alongside insulation and heating choices such as underfloor heating or radiators," says Richie Atkinson.
If however you're upgrading your heating during a home renovation project, you'll need a heat pump survey first. "Surveys assess property size, insulation levels, existing radiators and pipework, and local climate," explains Richie. All this is necessary in order to work out heat loss calculations as there may be some remedial work that needs to take place prior to installation.
Potential home upgrades
"Older buildings are typically less thermally efficient than modern ones," expands Hamid Salimi. "As a result, additional insulation often needs to be fitted. This includes loft insulation, draught excluders, and sometimes internal wall insulation.
"In an existing building, the pipework and radiators might also need to be upgraded, and this can take time and require additional materials, so this is worth factoring into your plans," he adds. "However, when installing a high-temperature heat pump that operates at higher temperatures, it can remove or reduce the number of radiators that need to be replaced."
"A common misconception is that every radiator must be ripped out," notes TJ Roots. "In reality, many existing radiators work perfectly well. What really matters is the size of your pipework. If the diameter of the pipe is 10mm (about the width of a AAA battery), then you're good to go."
Paperwork requirements
It might also be that you also need to get your home paperwork updated prior to installing an air source heat pump advises TJ Roots. "At the moment, a valid energy performance certificate (EPC) is needed to access the BUS grant, but it doesn’t have to be top-rated.
"Plenty of heat pumps are installed in homes rated D or E, especially where there’s cavity wall insulation or a mix of older and newer building fabric. If you’ve made renovations since your EPC was issued, a new one may even show your home performs better than you thought it would.
"But, if you don't have an EPC, it's easy to arrange one. If you chose Octopus as an installer for example, we will deduct the cost from your final bill if you do decide to install a heat pump. Although soon, even this won’t be needed," he says, "as the government has vowed to axe the EPC requirement by the end of 2027 as part of a mission to cut red tape."
One other thing to note, says TJ, "is that if your house was built before 2000, an installer is likely to ask you whether you have asbestos. If there’s any doubt, you may need an asbestos test before proceeding. Fortunately, many installers, including Octopus, will cover the cost of the test."
How much space do I need for installing a air source heat pump?
So what space do you need for installing an air source heat pump? In terms of inside and outside your home, it's generally less than you might think.
They'll function best when supplied with a good air flow, so with that in mind, they're best located in more open areas of the garden or outside space, rather than down narrow alleyways. You'll also want to ensure it's easily accessible for maintenance, so it's best to locate on the ground level rather than on a roof if possible, but if you don't have the room, a flat roof is an option open to you.
And, if you're wondering whether noise will influence where you install the pump, find out more in are air source heat pumps noisy?
"Air source heat pumps require an outdoor unit, typically installed next to an external wall," confirms Richie Atkinson. "Updated air source heat pump planning permission regulations from 29 May 2025 also allow outdoor units to be installed within one metre of a neighbouring boundary," he adds.
"A heat pump doesn’t need a huge garden, agrees TJ Roots. "Installers typically look for a clear outdoor space roughly the size of a small shed (2m x 2m x 3m). Most homes already have suitable spots: beside a wall, near a fence, or along a side return."
Inside your home, "internal components may include controls and a hot water cylinder, depending on the system design," notes Richie.
"Most homes already have an airing cupboard or utility room that’s perfect for the hot water cylinder," TJ tell us, "but if not, your installer can usually find a clever spot for it during the survey. We’ve seen them put in kitchen cabinetry, attics and all manner of places and they can be smaller than you think.
"If your existing cylinder is heat pump compatible of course, then no changes need to be made," he adds. "Many newer cylinders can work with a heat pump even if they don’t explicitly say so."
In a new build, you can however consider including a plant room in your design to house the cylinder and buffer tank, or low loss header if needed. This is around a third of the size of the hot water cylinder. There will also be an ASHP control box which is around 400mm x 400mm x 100mm deep, and a number of circulation pumps and pipework, as well as a manifold and control box for any underfloor heating.
Placing it in a plant room allows enough space for the materials and pipework but also for any engineer to perform any future repairs or heat pump maintenance. By putting it all together it is easier for the engineer to see all the components in one place, and also understand the circuits and controls.
It's worth noting that usually the preparation work such as building a solid base for the outdoor unit to stand on would also need to be in place before the installation date.
How long is the installation process?
In terms of how long it takes to install an air source heat pump, the answer can vary. In a new build, it will get absorbed into the overall build schedule, meaning it won't necessarily add extra time to your project.
When retrofitting a heat pump however, then it's less easy to specify an exact time frame as it will depend on whether you include the remedial work within the scope of the installation period.
"Installing an air-to-water heat pump is more than just the placement of an indoor and an outdoor unit, therefore there is no definite timeframe as it depends on several factors, including the type of home and heat pump, as well as if you require any additional work," explains Hamid Salimi.
"Air-to-air heat pump systems in comparison, are relatively simple to install, with a standard installation typically taking one to three days depending on the property," he notes. They’re generally less expensive to install than air-to-water systems as well, as they don’t require radiators or upgraded pipework."
In general, at E.ON Next, "most installations are completed within up to five days, depending on the complexity of the work," says Richie Atkinson.
Once it's physically installed, the installer will also commission the air source heat pump system and give the homeowner a handover to explain how it all works.
What happens after the installation?
Once your air source heat pump has been installed you should not need to do much, as the system should be commissioned by the installer. The installer should hand over the system to you and explain how it works and only allow you to change settings that you are fully competent to do.
Most of the time the maintenance on air source heat pump systems is visual. There will be inspections that you can do such as checking the outdoor unit has free air movement and is not blocked up with leaves or other debris. You can also check the insulation on all pipework is intact and that there are no visible signs of leaks or corrosion on the pipework or casing.
You will however need an annual service on your air source heat pump and the central heating system. Any non-visual maintenance will again need to be carried out by a suitably qualified and experienced engineer.
Looking for more information on air source heat pumps before you sign on the dotted line? Take a look at our comparison guide on air source heat pumps vs ground source heat pumps, find out how much electricity a heat pump uses and how to establish what size heat pump you might need in your home.
