Best Places to Install an Air Source Heat Pump at Home

Before you have an air source heat pump installed, it’s crucial to engage with your installer about the ideal location for the indoor and outdoor units (and hot water cylinder if required).

You should consider the following when placing your air source heat pump: adequate space and airflow, accessibility for maintenance, compliance with building regulations, ease of installation, potential for noise reduction and visual aesthetics. Thanks to relaxed planning permission rules from May 2025, installing a heat pump has never been easier.

In this guide, we will explore the best locations for installing an air source heat pump at home, along with factors to consider and locations to avoid. We’ll also summarise the relaxed planning permission rules that are due to come into effect from 29 May 2025.

Cinergi is a family-run company with 30+ years of experience in home heating. We specialise in heat pump installation and other renewable energy solutions such as ground source heat pumps, solar panels and EV charging stations. If you are considering an air source heat pump but have questions about where to install it, please fill in our contact form to book a call with one of our friendly team.

What needs to be installed for an air source heat pump?

First, let us be clear on what exactly needs to be installed.

Outdoor unit – this houses the compressor and other critical components and should ideally be placed in a well-ventilated area, typically a garden or driveway.

Indoor unit – this includes the heat exchanger and air handler and should be installed in a central location within the house, e.g. in a utility room.

Hot water cylinder – you will need to install a hot water cylinder if you don’t already have one. It’s usually installed in a utility area, airing cupboard, or perhaps a loft. The proximity to bathrooms and the kitchen is essential to reduce heat losses through pipework and ensure quick access to hot water.

Note that your central heating system may also need upgrading, e.g. new radiators or underfloor heating.

Let’s take a closer look at the considerations for installing these components.

What Should You Consider When Placing Heat Pumps?

Changes to planning permission rules (29 May 2025)

Thanks to changes to permitted development rights for heat pumps (effective 29th May 2025), the following new rules will apply:

• Scrapping of the 1m boundary rule: You will be able to install the external heat pump unit within 1 metre of your property boundary without planning permission.
• Increase in maximum size: The size limit for units is increasing from 0.6m³ to 1.5m³ – great news for larger properties.
• More than one heat pump for detached dwellings: If you live in a detached home, you’ll be allowed to install two heat pumps instead of just one.
• Air-to-air systems included: These will be included within permitted development.
• Less noise concern: Installers must adhere to more stringent noise assessments. While the noise limit remains at 42 dB, they must ensure the heat pump stays below this level even when working at maximum capacity.

Location, size, and ventilation

ASHPs come in different sizes and capacities, but every heat pump needs space around it to ensure sufficient airflow. This is crucial for efficient heat transfer, as you don’t want cold air bouncing off the wall and into the unit, as this will affect its efficiency.

The outdoor unit is likely to be around a metre wide and 1.5m tall, so a suitable space would be 3.5m2. The internal unit is roughly the size of a gas boiler, so roughly 70cm high and 30cm wide.

It’s essential to consult with a suitably qualified heating engineer like Cinergi to make sure you have enough space for both the indoor and outdoor unit.

Noise output

Air source heat pumps do generate some noise during operation, but modern systems are becoming much quieter. Careful placement of the unit can help minimise any sound further, and from 29 May 2025, new rules will tighten how noise levels are assessed. While the noise limit remains at 42 db, installers must now prove that your heat pump stays within this limit even during colder weather and at busier operating times, giving you and your neighbours extra peace of mind.

To put it into context, a washing machine is around 70 db, and busy traffic is 85 db. A typical gas boiler registers around 60 db, the same as a conversation in your ‘indoor voice’! So, unless you live in a very quiet location, the sound of a heat pump should be almost imperceptible, especially when you are inside.

Neighbours

Before 20 May 2025, planning rules stated that a heat pump must be at least a metre away from the boundary of your property. However, from that date, no such rule applies. This is great news for smaller properties with limited outdoor space, who will no longer need to seek planning permission.

However, being considerate of your neighbour’s peace and privacy is important and can go a long way. Talk to them about your plans and place the unit in a location that minimises noise and visual impact on neighbouring properties.

Further reading – Do I have to tell my neighbours I’m installing an air source heat pump?

Aesthetics

Aesthetics play a significant role in determining the placement of an air source heat pump. Homeowners often prefer installing the unit in a discreet location that doesn’t compromise the overall appearance of their property. Consider areas that blend well with your home’s design, or opt for creative solutions to integrate the ASHP seamlessly into your outdoor space.

Places to avoid placing an air source heat pump

While ASHPs are versatile, there are certain locations to avoid placing the external unit.

1. Confined spaces: Avoid installing ASHPs in small, enclosed spaces where airflow is limited. They need adequate ventilation in the outside air for safe and efficient operation.
2. Areas with obstructions: Areas with significant obstructions, such as tall trees, structures, or nearby buildings, can obstruct airflow and impact the heat pump’s efficiency.
3. Highly polluted areas: Air source heat pumps may struggle in highly polluted places like inner city areas where the air quality is poor. The contaminants in the air can affect the system’s components and performance.
4. Direct sunlight: While ASHPs utilise heat from the air, direct exposure to intense sunlight can cause the unit to overheat, reducing its efficiency and potentially damaging the system.
5. Areas prone to flooding: Flood-prone areas pose a risk of damage to outdoor units and the overall system.
6. Structurally unsound areas: Installing a heat pump in areas with unstable or weak structures may pose a risk to the unit’s stability and safety, potentially leading to structural damage and compromised performance.
7. Inaccessible or hard-to-reach locations: Locations that are difficult to access for maintenance, repairs, or installation should be avoided to ensure easy servicing and upkeep of the heat pump system.
8. Where noise pollution may be a concern: For example, you may want to avoid putting the unit too close to a downstairs bedroom window.

What are the ideal locations for an external heat pump unit?

So considering all of the above, let’s take a look at some ideal locations for your new ASHP. As it requires free-flowing, ambient air to work, so it must be located outside.

1. Garden/courtyard/patio: These are popular choices, but ensure the ground is stable, there is no risk of flooding and that there is adequate airflow around the unit.
2. Roof or terrace: In some cases, the outdoor unit can be installed on a flat roof or terrace, provided it’s a metre from the roof’s edge.
3. Driveway: This can be a discreet location if the driveway is large enough and also provides maximum accessibility.
4. Purpose-built shelter: This can protect the unit from the elements, reduce noise and maintain the aesthetic of your property.
5. Raised platform: Elevating the ASHP on a platform or stand can prevent snow accumulation and facilitate better drainage, which is especially important in colder and wetter regions.
6. South-facing: If possible, install the ASHP on a south-facing wall or roof to maximise exposure to sunlight.

Considering an Air Source Heat Pump? Get in Touch with Cinergi Today

Installing an air source heat pump is a wise choice for those looking to reduce their carbon footprint and lower their energy bills – and thanks to the changes to planning permissions in May 2025, it’s never been easier.

Our team of experts can guide you through the process, recommend the ideal placement, and help you select the right air source heat pump for your needs. Contact us today to start your journey toward a more energy-efficient and environmentally friendly home.