As you would expect the main component of an air source heat pump, is the heat pump unit itself. Additional components may include a hot water cylinder (if the heat pump is to provide hot water as well as space heating), and a buffer tank. We will explore each of these in further detail below.
Heat pump unit
The typical size of an air source heat pump is between 1 and 1.5m high and between 0.5 and 1m wide. It will need to be fitted to one of the outside walls of your home or be placed on the ground next to it. If on the ground, it will need to stand on something solid enough to bear its weight and vibration (so that the noise during operation is not amplified).
The heat pump unit needs to have space around it to allow for a good flow of air (heat pumps draw in air from the back and sides and release it from the front). Fitting an air source heat pump unit near the corners of a building is to be avoided. This is because cold air will bounce back from the wall and go behind the unit reducing the average temperature of the air that heat is being extracted from (making the heat pump less efficient).
It is possible to site a heat pump unit in your garden, further away from the house, but there are disadvantages to doing this. These are additional heat loss in the pipes running between the house and garden and the potential for additional maintenance costs as the pipework is less accessible. If the heat pump is fitted in your garden, you will also need to manage any plants or shrubs nearby to keep them at least a meter away.
It is also advisable to avoid putting a heat pump directly outside or below a bedroom window, as the noise of a heat pump running (which is similar to a fridge) could be irritating at night when the occupant of the room is trying to sleep.
Installing an air source heat pump in a domestic property does not usually require planning permission, as it is classed as permitted development. However, there are conditions that apply. These include a requirement that all parts of the air source heat pump must be at least one metre from the property boundary and (if installed on a flat roof) be at least one meter away from the roof’s edge. Permitted development rights do not apply to homes that are listed or within a conservation area – always check with your local council’s planning department for guidance if you are not sure.
Hot water cylinder
If you want to use an air source heat pump for heating hot water as well as space heating you will also need to find space for a hot water cylinder, requiring cupboard space with a footprint of approximately 80cm x 80cm. If you already have a cylinder replacing it with one suitable for use with a heat pump should not cause you any space issues. If you don’t have space, there are alternatives possible. For more information on this, see our blog on ‘Can I get all my hot water from an air source heat pump?’
Buffer tank
A buffer tank is simply an insulated vessel that adds an additional volume of hot water to the heating system This enables it to act like a battery for the heating system, allowing it to store more energy from the heat pump. A buffer tank also helps a heat pump run more efficiently by reducing the need for short cycling (during which the heat pump keeps turning off and on).
A fixed-output heat pump needs a buffer tank to manage fluctuations in demand. Even with an inverter heat pump (which can modulate its output) a buffer tank is needed if different temperatures in different rooms are required. A buffer tank helps heat pump systems run efficiently (by eliminating short cycling) and at the right temperature.
A buffer tank also allows for the separation of the liquids in the two circulation systems – one in the heat pump and the other around the heat emitters (radiators or underfloor heating). This is important because the water temperature needed by the two circuits is different.
The size of the buffer tank will depend on the size of your home and other factors, such as the amount of insulation it has. The buffer tank may be similar in size to a hot water cylinder and to save space may be situated above or below the cylinder or integrated into one tall vessel. To save space a buffer tank could also be put in a loft or basement.
Summary
This blog is intended as a general guide only to the many factors to be considered when selecting where to put a heat pump outside and whether space is needed (and how much) for a hot water cylinder and/or a buffer tank. Designing an air source heating system for optimal performance is a job for a professional installer. To find one go to the Microgeneration Certification Scheme website.
If the idea of enhancing your home’s energy efficiency through strategic retrofitting and delving into the realm of low-carbon alternatives intrigues you, then our SuperHomes project could be a perfect match. Our community members are at the forefront of redefining sustainable living. For further details, feel free to visit www.superhomes.org.uk
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.
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.
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.
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.
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.
Air source heat pumps generate a certain level of noise during operation. Modern ASHPs are designed to be quieter, but placing them strategically can further minimise any noise output. A responsible installer will carry out a noise assessment and advise the best location so as not to disturb you or your neighbours.
To put it into context, a washing machine is around 70 decibels and busy traffic is 85 decibels. A typical gas boiler registers around 60 decibels, 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.
Your heat pump must be at least a metre away from the boundary of your property and comply with other conditions as set out in the Town and Country Planning Order (England, 2015).
Providing you don’t need planning permission, there is no obligation to tell your neighbour that you plan to install an air source heat pump. However, being considerate of their 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 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.
While ASHPs are versatile, there are certain locations to avoid placing the external 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.
Installing an air source heat pump is a wise choice for those looking to reduce their carbon footprint and lower their energy bills. If you’re considering an air source heat pump for your home, get in touch with Cinergi, a leading heating specialist on the South Coast.
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.