How Much Space Does An Air Source Heat Pump Need?

Last Updated on June 27, 2025

Thinking of upgrading to a greener, more efficient heating system? If you’re considering an air source heat pump, one of your first questions is likely: how much space does an air source heat pump need?

Understanding air source heat pump space requirements is critical for successful installation and long-term performance, especially in the UK, where property sizes and regulations can vary widely. 

If you’re still weighing up whether a heat pump is the right move for your home, understanding the pros and cons of air source heat pumps can give you a clearer picture beyond just the space considerations.

In this guide, we’ll break down exactly how much outdoor and indoor space you need, installation regulations, and best practices for ensuring your property is heat pump-ready.

How Much Outdoor Space Do You Need for an Air Source Heat Pump?

The outdoor unit is the heart of your air source heat pump system. In most UK homes, this unit is placed at the rear or side of the property.

• Minimum clearance requirements: Most systems need around 1 metre of clearance in front of the unit to allow for unrestricted airflow.
  
• Unit dimensions: A standard unit measures approximately 1m x 1.5m x 0.5m (H x W x D) but this can vary based on the size of air source heat pump required.
  
• Installation surface: It must be placed on a flat, stable base, usually a concrete slab or sturdy wall brackets. Installation complexity, especially in tight or awkward spaces, can also impact how much a heat pump costs, so planning ahead with a quote is a smart first step.
  
• Ventilation: Avoid placing the unit in enclosed courtyards or alcoves where airflow could be restricted.

System placement plays a key role in overall air source heat pump efficiency, especially when airflow is restricted or blocked by surrounding structures.

Efficient placement can also reduce how much electricity your air source heat pump uses by improving airflow and reducing system strain.

Can You Install an Air Source Heat Pump in a Small Garden?

Yes, you can, small gardens or limited outdoor areas aren’t necessarily a barrier.

• Compact models: Many manufacturers now offer slimline units suitable for tight spaces.
  
• Wall-mounted options: In space-constrained urban properties, high wall mounting can be a smart alternative.
  
• Noise considerations: Ensure units are positioned away from bedroom windows or neighbouring properties to comply with Permitted Development noise limits (typically 42 dB at 1m).

Proper placement can also improve system performance and help reduce your heat pump running costs over the long term.

Pro tip: Eco Happy’s surveyors will assess your outdoor space and recommend the best placement with minimal disruption.

How Much Indoor Space Is Needed for an Air Source Heat Pump?

Unlike gas boilers, air source heat pumps need additional indoor components like:

• Hot water cylinder (typically 180–300 litres)
  Stores heated water for taps and radiators. A larger household will need a higher-capacity cylinder to meet daily demand.
  
• Buffer tank (optional, but helps maintain system efficiency)
  Acts as a thermal store to reduce short cycling, improve system response times, and support consistent heat distribution. Wondering if heat pumps need a water tank in every case? The answer depends on your home’s setup and hot water demand.
  
• Control systems
  Includes thermostats, programmers, and sometimes smart home integration panels, usually wall-mounted and compact.

Typical indoor requirements:

• Floor area: Around 1–2 square metres
  Enough to accommodate a cylinder and any ancillary components like valves or expansion vessels. Space should allow for easy access during servicing.
  
• Height: Standard ceiling height is usually sufficient
  Most cylinders and buffer tanks fit under 2 metres. Just ensure there’s clearance above for pipework connections and maintenance.
  
• Room types: Commonly installed in utility rooms, airing cupboards, garages or lofts
  The key is proximity to plumbing and heating circuits. Ventilated, frost-free areas are preferred to protect system components.

Does the Heat Pump Location Affect Performance?

Yes, location directly impacts efficiency and lifespan. Proper placement ensures optimal air intake and discharge, reducing strain on the system.

• Avoid direct sunlight or enclosed spaces where heat build-up can affect performance.
  
• Shelter from wind and rain is ideal, but without enclosing the unit fully.
  
• Avoid clutter around the unit, plants, fences, or bins can reduce airflow.

Even in colder climates, well-installed heat pumps can perform efficiently provided the outdoor unit has enough space and airflow. Read our article on how heat pumps perform in cold weather and what to expect during winter months.

Are There UK Building Regulations for Air Source Heat Pump Space Requirements?

Yes, in most cases, air source heat pumps fall under Permitted Development Rights in England and Wales, if specific space and noise limits are followed:

• Maximum volume of outdoor unit: Must be under 0.6 cubic metres
  
• Distance from property boundary: At least 1 metre from the boundary
  
• Listed buildings or conservation areas: May require planning permission
  
• Noise level limits: Must comply with the Microgeneration Certification Scheme (MCS) noise assessment

What If You Don’t Have Enough Space for An Air Source Heat Pump?

Don’t worry, lack of space doesn’t mean you can’t install a heat pump.

Hybrid systems: Combine heat pumps with existing gas boilers

If there’s not enough room for a full system, a hybrid setup can be the perfect solution. It uses the heat pump most of the time and switches to your boiler only when needed, saving space and money.

If you’re considering replacing your gas boiler with a heat pump, there are both space and cost considerations to factor in, especially when converting older setups.

Split systems: Separate indoor and outdoor components for more flexibility

Unlike monobloc systems, split systems give installers more freedom to place components where they fit best. You might have the outdoor unit in your garden and the indoor unit tucked neatly in a cupboard or utility room.

Bespoke installation: Eco Happy engineers can often find creative solutions

Our team has worked with all kinds of properties, from flats to old stone cottages. Whether it’s mounting the unit on a wall, hiding the cylinder in the loft, or choosing a slimline model, we’ll find a setup that works for you.

Bottom line? Lack of space doesn’t mean lack of options, just smart planning.

How Can You Tell If Your Property Is Suitable for an ASHP?

Eco Happy offers a free property suitability survey where we assess:

• Outdoor clearance and access
  
• Indoor cylinder and component space
  
• Ventilation and drainage routes
  
• Sound level compliance
  
• Your home’s current heating layout

We’ll then provide a tailored system recommendation with a no-obligation quote.

Want to learn more about whether your house is suitable for a heat pump? We’ve covered what types of properties work best and which challenges to anticipate. Even old houses can support air source heat pumps with the right planning.

What Are the Best Practices to Maximise Space and Efficiency?

Here’s how to ensure a successful installation and maximise your space:

Pre-install tidy-up: Clear the installation area of debris, plants or obstructions.

Choose experienced installers: Proper placement = better performance. If you’re planning next steps, our installation guide for air source heat pumps will walk you through the full process.

Ask for a system layout plan: Visualise where each component will go.

Upgrade insulation: Smaller systems can be used in well-insulated homes.

Plan cylinder storage wisely: Use under-stairs cupboards or garages.

Request Your Free Air Source Heat Pump Quote from Eco Happy

Upgrading to a renewable heating system doesn’t have to be stressful, even if space is tight. 

At Eco Happy, we’ve helped hundreds of UK homeowners and landlords navigate air source heat pump space requirements with ease. Our expert team handles everything, from surveying and planning to installation and support.

Ready to find out if your home or property is suitable?

Get your free, no-obligation air source heat pump quote today

We’ll assess your space, recommend the right system, and help you cut your energy bills, all with zero hassle.