If you’re considering installing a renewable heating system and wondering: how much space does an air source heat pump need? This is one of the most common and crucial questions asked by UK homeowners, landlords, and commercial property owners who are exploring the switch to low-carbon heating.
In this guide, we’ll break down the space requirements for outdoor units, pipework, and hot water cylinders, plus, we’ll discuss solutions for properties with limited space, noise regulations, and recommended unit sizes based on home size and heating demands.
How Much Physical Space is Required for An Air Source Heat Pump?
Air source heat pumps (ASHPs) are installed outdoors, usually on the ground or mounted on an external wall. The outdoor unit typically measures around:
- Height: 800–1,600 mm
- Width: 800–1,200 mm
- Depth: 300–500 mm
Minimum clearance: You must allow at least 30 cm of space around all sides and at least 1 metre clearance in front of the fan to ensure proper airflow and performance.
According to the Energy Saving Trust, the unit should be installed on a solid, level base and positioned away from enclosed or noisy areas such as tight alleyways or underneath windows to reduce noise disturbance and ensure free air circulation.
This base could be a concrete plinth or a secure wall bracket if elevation is needed.
What Size ASHP Do I Need Based on Property Type and Energy Needs?
The size (capacity) of an air source heat pump is based on your home’s heat demand, influenced by floor area, insulation, and property age. Here’s a rough guideline:
| Property Type | Estimated Floor Area (m²) | Heat Demand (kW) | Recommended ASHP Size (kW) | Approx. Outdoor Unit Space (m²) |
|---|---|---|---|---|
| 1-bedroom flat | 45–60 | 3–4 | 4–5 | 1.2–1.5 |
| 2-bed semi-detached house | 70–90 | 5–6.5 | 6–8 | 1.5–2 |
| 3-bed detached house | 100–130 | 7–10 | 9–12 | 2.0–2.5 |
| 4+ bed large property | 150+ | 10–15 | 12–16 | 2.5–3.5 |
| Small commercial building | 200–500 | 20–50 | 20–60 | 3.5–6+ |
Figures are estimates and should be confirmed via an MCS-certified heat loss calculation.
You can read more about energy efficiency performance on the Department for Energy Security and Net Zero website.
What If my Property Doesn’t Have Enough Outdoor Space?
If you’re limited on garden or exterior wall space, you’re not out of options. Here’s what you can do:
1. Use a split system
Split systems place the compressor outside but the heat exchanger inside, reducing the outdoor unit size.
2. Opt for vertical installation
Some ASHPs can be stacked vertically or mounted on walls above ground level (with planning permission where required).
3. Use shared systems in flats
For flats or apartments, shared heat pump systems for a block can reduce the need for each unit to have its own outdoor heat pump. We have a dedicated article on installing a heat pump in a flat that provides helpful insights about installation challenges.
4. Explore other low-carbon alternatives
Ground source heat pumps or hybrid systems may be more viable if space is severely limited.
Planning rules: ASHPs are usually permitted developments, but check with your local council if space is limited or if you live in a conservation area.
How Noisy is An Air Source Heat Pump and What Space Considerations Does this Involve?
While modern air source heat pumps are designed to be quiet and efficient, noise is still an important factor, especially when considering where to install the unit.
Homeowners often wonder whether the system will disturb everyday living or potentially impact neighbours.
Under UK planning regulations, the air source heat pump must not exceed 42 decibels (dB(A)) when measured 1 metre from your neighbour’s nearest habitable room window.
This is part of the criteria that allows most domestic heat pump installations to fall under permitted development.
To help you understand how various systems compare, here’s a breakdown of the noise levels for some of the most common domestic ASHP models:
| Brand / Model | Noise Level (dB at 1m) |
|---|---|
| Mitsubishi Ecodan 8.5kW | 45 dB |
| Samsung Eco Heating System | 40 dB |
| Vaillant aroTHERM plus 7kW | 36 dB |
Tip: To avoid any planning complications or nuisance complaints, it’s best to install the outdoor unit away from bedroom windows, property boundaries, and enclosed spaces.
If your installation area is particularly tight or urban, consider using acoustic enclosures or selecting ultra-quiet models like the Vaillant aroTHERM plus.
Does the Hot Water Cylinder Need Additional Space Inside the Home?
Yes. Most ASHP systems include a hot water cylinder. Here’s what to expect:
- Cylinder capacity: 150L–300L, depending on the household size.
- Space required: 0.5–1.2 m² — usually fitted in an airing cupboard or utility room.
If space is tight:
- Use a heat pump-compatible combi system (though rare and lower output).
- Explore thermal stores or wall-mounted tanks with a slimmer profile.
How Can I Ensure my ASHP System Fits my Property Perfectly?
This is where expert guidance is essential. Heat pump systems are not one-size-fits-all, and the most space-efficient system must still meet your home’s heat load.
If you’re based in Newcastle or anywhere across the North East of England, Future Heat can assess your home’s space and energy needs and design a bespoke system that meets your goals.
Frequently Asked Questions (FAQs)
Yes, but it’s more complex. You’ll likely need permission from the freeholder and potentially neighbours. Shared ASHP systems or smaller units may be considered.
Yes, but for airflow, not combustion. The unit must have unobstructed air circulation on all sides for efficiency and safety.
Typically up to 30 metres, but longer distances may reduce efficiency. Insulated pipework is used to minimise heat loss.
Only if that structure is well-ventilated and allows sufficient airflow. Enclosing a heat pump too tightly can reduce performance and void warranties.
According to research from UK Green Building Council, installing energy-efficient systems like ASHPs can boost home value, particularly as EPC regulations tighten across the UK rental market.
Our Verdict
An air source heat pump doesn’t require a huge amount of space, but it does require the right kind of space.
Proper airflow, planning permission considerations, noise limitations, and cylinder placement are all factors to consider when installing a system.
Most UK homes can accommodate an ASHP with the right design and even if space is limited, alternative solutions exist.
With growing pressure to decarbonise home heating, these systems are a smart investment in both sustainability and future energy savings.
If you’re unsure whether your property has enough space for an air source heat pump or you want a professional assessment and quote, Future Heat offers free consultations for homes and businesses in Tyne and Wear and across the North East.
Myles Robinson is a seasoned expert in the boiler and home improvement industry, with over a decade of experience. He is deeply committed to environmental sustainability, actively promoting energy-efficient heating solutions to help households reduce their carbon footprint. By combining industry expertise with a dedication to environmental responsibility, Myles continues to lead efforts in transforming home heating practices towards a more sustainable future.
