Permitted development rights (PDRs) for air source heat pumps in Wales were updated on 1 June 2026, under the Town and Country Planning (General Permitted Development) (Amendment) (Wales) Order 20261. The Welsh Government states that domestic heat pumps benefit from permitted development rights, meaning that in most cases planning permission is not required, subject to limitations and conditions1. MCS, the certification body, said the changes "will ease the administrative burden for installers and increase the number of eligible properties"2.
The main changes concern how many units a home may have, how large they may be and where they may sit. MCS reports that the number of heat pumps permitted on a detached dwelling house has increased to two, "rather than the previous limit of one", and that the two units in operation together must not exceed the 40db limit2. The size limit of a heat pump has increased from 1m3 to 1.5m3 for dwelling houses2. Heat pumps can be installed within 3m of the property boundary, and air-to-air heat pump installations are now allowed2. MCS also states that heat pumps can now be installed on a wall or roof which fronts a highway, while a heat pump cannot be installed on a pitched roof and, if installed on a flat roof, it must not be situated within one meter of the external edge of that roof2.
The Welsh Government's own guidance sets out the conditions that apply. For a detached home, up to two air source heat pumps may be installed on or within the curtilage; for a home that is not detached, one1. The volume of the outdoor compressor unit, including any housing, must not exceed 1.5 cubic metres1. Installation must comply with MCS 020(a), which sets installation standards including assessment of sound impact on neighbours1. A unit cannot be installed if a standalone wind turbine is already installed within the curtilage, cannot be installed on or within the curtilage of a listed building, and must be for heating purposes or heating and cooling, not cooling only1. Within a Conservation Area, a unit cannot be installed on a wall or roof which fronts a highway1. Outside a Conservation Area, it cannot be installed on a wall fronting a highway above the level of the ground floor storey1. The unit must, so far as practicable, be sited to minimise its effect on the external appearance of the building and on the amenity of the area, and must be removed as soon as reasonably practicable when no longer needed for or capable of microgeneration1.
| Change in Wales from 1 June 2026 | Previous position |
|---|---|
| Up to two air source heat pumps on a detached home | One2 |
| Outdoor unit volume up to 1.5m3 | 1m32 |
| Installation within 3m of the boundary | 3m restriction removed2 |
| Air-to-air heat pumps allowed under PDR | Not allowed2 |
| Units allowed on a wall or roof fronting a highway | Not allowed2 |
MCS states that all installations in Wales falling under PDR must comply with MCS 020 a): Air Source Heat Pump Sound Calculation, "regardless of whether it is an MCS certified installation"2. It adds that the Welsh Government will seek to introduce a new condition in Part 40 that any acoustic barrier required to ensure compliance with MCS 020(a) must be permanently retained and maintained2. The Welsh Government directs readers to the 2026 Order read in conjunction with the 2012 Order for context and how the changes apply1. Ground source and water source heat pumps remain permitted development within the curtilage of a dwellinghouse1.
"Permitted development rights (PDRs) for air source heat pumps were updated on 1 June 2026"
Why it matters for households
Planning permission is one of the practical barriers between a household and a heat pump, and the Welsh changes widen the set of homes where an installation can proceed without an application. A larger permitted unit volume of 1.5 cubic metres brings more models inside PDR, and allowing two units on a detached home matters where a single unit cannot meet the whole heating and hot water load. Allowing air-to-air systems under PDR opens a route for homes where ducted warm air, rather than a wet radiator system, is the practical option; MCS notes that air-to-air heat pumps do not provide hot water4. The removal of the 3m boundary rule gives more siting freedom on smaller plots, though the noise calculation still governs where a unit can go2. For a household, the effect is fewer cases where a planning application, with its cost and delay, stands between a decision and an installed system. The conditions that remain, including the listed building exclusion, the Conservation Area restrictions and the MCS 020(a) sound assessment, mean the position still varies by property and location1.
What happens next
MCS states that work is ongoing to bring air-to-air heat pumps into scope of the MCS Scheme, including when installers can apply to their certification body to become MCS certified for air-to-air heat pump systems2. MCS also states that when air-to-air heat pumps are brought into the scope of MCS later this year, a grant of up to £2,500 may be available for the technology under the Boiler Upgrade Scheme5. The Welsh Government states that the most recent changes can be viewed in the Town and Country Planning (General Permitted Development) (Amendment) (Wales) Order 2026, to be read with the 2012 Order1. No commencement date for the proposed Part 40 acoustic barrier condition has been reported2.
Sources5 cited
- Planning permission: domestic heat pumps | GOV.WALES, gov.wales
- Changes to permitted development rights (PDR) in Wales from 1 June 2026 - MCS, mcscertified.com
- How much space does an air source heat pump need?, fuseenergy.com
- Air Source Heat Pump - MCS, mcscertified.com
- Boiler Upgrade Scheme - Consumers - MCS, mcscertified.com