Air source heat pump installation

What is an air source heat pump?

An air source heat pump is a renewable heating system that extracts heat from outdoor air and uses it to supply heat and hot water to your home. It’s a low-carbon alternative to traditional heating systems, such as gas boilers, using electricity to take warmth from the air outside and transfer it to your central heating system. 

An Air source heat pump is a sustainable heating solution, helping to reduce reliance on fossil fuels and transition to renewable energy sources for home heating and hot water.

Benefits of air source heat pump installation

An air source heat pump can provide efficient heating and cooling, using much less energy compared to traditional heating systems, resulting in lower energy bills.

They can - with careful system design - significantly decrease your monthly energy costs and reduce your carbon emissions. 

Choosing the right installer for your heat pump system

Look for an installer who is accredited by reputable organisations such as the Microgeneration Certification scheme (MCS). This is essential if you want to offset total installation costs with government funding, which requires a certified installer following an MCS approved installation process. 

Ensure the installer has undergone installer training and adheres to industry standards. Check the installer’s portfolio and ask for references to ensure they have experience with air source heat pump installations. Compare several installers and check their qualifications, customer reviews, and service costs. 

We are happy to provide the names of installers trained on our products who serve your local area.

The air source heat pump installation process

On-site survey and preparation

During the design and quote part of the process a heating engineer will usually visit your home to ensure everything is ready for the installation. In most cases existing pipework and electrics can be used although some adjustments may need to be made.

They will check the space where the outdoor unit could go, the insulation in your home, and your current heating system.

 They will also assess your home’s energy efficiency and may provide recommendations for improvement which will help to ensure the optimal performance of your heat pump. They will carry out a heat loss calculation which will determine how much heat your home requires and what size heat pump is required to keep your home warm. 

They will also discuss with you where indoor components will be sited and whether you need to change any existing radiators or want to install underfloor heating in any areas. 

If you already have a hot water tank, it may simply be a case of switching this out with one suitable for a heat pump system. However if you do not, or you are installing the heat pump as part of a larger building project such as an extension or renovation, then there may be more to agree.

As well as a cylinder, you will also need a heat pump controller and may require space for an expansion vessel and buffer tank. 

The expansion vessel accommodates any increases in water volume which occurs during heating or cooling, keeping the pressure of the system stable by absorbing the extra volume. This helps maintain a constant pressure which can help the system to be energy efficient.

Buffer tanks are used for storing hot water to reduce cycling of a heat pump by holding a circuit of heated water that runs through radiators and underfloor heating. They are often recommended to ensure energy efficiency and the longevity of your heat pump, but some heat pumps operate more efficiently without them. Whether you require one will depend on the specifics of your home and heating system. 

Buffer tanks are usually around a third of the size of the hot water cylinder. 

Our own system cylinders come with the controller built into them for space saving and fail-safe integration. Some models also have buffer tanks and other hydraulic components built in to create a neat, compact footprint. 

Extra requirements for cooling

If you want to use your heat pump for cooling as well as heating purposes you will need to have fan coil radiators or underfloor systems in the areas that you want to cool. If these are not already in place you will, of course, need to replace any existing radiators.

Air source heat pump installation and connection process

The connection between the indoor and outdoor units is established through a refrigerant piping system. For this reason the outdoor unit is often situated near the outside wall of your property, and the pipe fed straight through the wall.  In situations where the heat pump is situated further away, the pipe can be laid in a trench from the heat pump to the wall. 

Whilst planning permission is not usually required for the outdoor unit, unless your home is listed or in a conservation area,  there are rules about where air source heat pumps can be sited to meet the conditions for permitted development. You can find out more about the rules for planning on our article about planning permission and rules for siting heat pumps.

The heat pump units are usually mounted on a stone, brick or concrete plinth on the ground to ensure that the installation is level and stable. Provision must also be made for condensate drainage (usually a gravel soak away is built in to the mounting platform for water to drain away underneath). Air source heat pumps can discharge 8 litres of water in a defrost cycle, so this is essential to prevent nuisance. 

They need to be sited in a position with minimal obstructions to good air flow and ideally not facing into the prevailing wind. 

Where space is tight external units can also be wall mounted on an external wall or installed on flat roofs with the proper careful planning. 

It is worth remembering that during the ashp installation process there will come a point when your old heating system will have to be removed before installing the heat pump. This will mean a period without heating and hot water being available. Your installer should make you aware of this and the projected timescale for the outage. 

The indoor unit and any additional tanks and controls are usually installed in a utility room, garage or cupboard where it can efficiently distribute heat and hot water around your home. 

Typical progress of an installation

• The first step of an installation usually involves fitting new pipework and radiators and replacing your hot water cylinder if you have one.
• Day 2-3 usually involves installing the heat pump itself, pipes and pumps that connect the system.
• The final day of your installation, usually around day 4 or 5, is when your installer will commission your heat pump system. This usually includes talking you through the set-up and how you can control temperarure and timings.

Heat pump running costs and funding

The cost of installing an air source heat pump will vary depending on factors such as the type and size of the heat pump, location, and complexity of the installation. The total price of buying and installing an air source heat pump is typically £10,000 - £14,000. 

In England and Wales you may be eligible for the government’s Boiler Upgrade Scheme (BUS) if you’re replacing your fossil fuel-powered gas boiler, which offers a £7,500 grant towards the overall cost. 

To be eligible for the grant, a valid, Energy Performance Certificate (EPC) from the last 10 years, with no recommendations for cavity wall or loft insulation is required.

You can find out more about the various current funding schemes and financial assistance available in your home nation in our article on funding for renewable energy measures.

Maintenance and upkeep of your air source heat pump

Regular maintenance is required to ensure the air source heat pump operates properly. Periodic checks by a professional can help avoid additional repair costs and prolong tjhe lifespan of the appliance. You can also do your part by keeping the external unit clean and free of debris.

Frequently asked questions about having a heat pump installed

Q. Can I install an air source heat pump myself? 

A. No, generally installers require professional qualifications and certifications to ensure safe and legal installation, particularly if you are decommissioning a gas boiler. If you want to receive government funding you will need an MCS certified installer. 

Q How long does it take to complete an air source heat pump installation?

A. Typically less than a week. The size and complexity of the system and the ease of access to the site and installation points will determine exactly how long it takes. 

Q. Do air source heat pumps use a lot of electricity? 

A. A Heat pump is designed to be energy efficient and when designed and run correctly with low flow temperatures. Obviously, if you are converting  from oil or gas you will use more electricity than before, but will be free of costs of fossil fuels.

Many modern heat pump installations combine solar panels and battery storage with the heat pump to reduce running costs further and insulate end users from fluctuations in energy bills caused by market forces beyond their control. 

Q. Is it worth installing an air source heat pump?

A. As part of the initial design and quote for your air source heat pump installation, you should receive data on how cost effective your system will be and whether you will save money on bills. The financial payback of the system will depend on your individual circumstances, how much funding you are eligible for and the nature of your property. 

Many homeowners facing the need to replace a boiler find that wih the much of the potential costs offset by funding,  the installation cost of a heat pump is not much greater than a replacement boiler and that lower bills will ensure an acceptable payback period for any difference.

When it comes to the environmental benefits of switching from burning fossil fuels, having a heat pump installed is without question a far better choice for the planet.

Conclusion and next steps

So is it worth installing an air source heat pump? We say yes, in almost every case. Air source heat pumps are a fantastic choice for heating your home, extracting heat from outside air to make your home cosy and heat hot water whilst reducing running costs and your carbon footprint.