Heat pumps for flats and leasehold homes: permission and design

Identify who controls every part of the proposed route

Begin with tenure, not product capacity. A tenant should read the tenancy agreement and ask the landlord about permanent alterations. A leaseholder should read the lease and identify the freeholder or managing agent; GOV.UK notes that the lease can state whether permission is needed for alterations. Shared owners may have both landlord and lease obligations. A share of freehold does not necessarily give one flat owner sole control over the façade, roof, balcony, structure or communal services. Obtain project-specific written decisions rather than relying on a neighbour's installation or a sales assurance.

Mark the whole physical route on photographs or a plan: outdoor unit and brackets or base, refrigerant or water pipes, electrical supply, isolator, wall penetrations, internal units or cylinder, condensate discharge, access for installation and future maintenance. Label which surfaces and spaces are inside the demise and which are common parts. Consent to put equipment inside the flat does not automatically authorise drilling the exterior, using a communal roof, crossing a corridor or draining onto shared land.

Keep lease consent, planning and building rules separate

A planning outcome does not override a lease or tenancy, and landlord or freeholder consent does not decide planning permission. Building regulations, electrical requirements, fire stopping, listed-building controls and local restrictions can be separate again. GOV.UK says fixed air conditioning and installing or replacing a heating system can require building-regulations approval or special rules in England. Ask each responsible body for its own decision and conditions, retain the correspondence and make sure the final installed design is the design that was considered.

This page cannot determine legal permission. Rules differ across the four UK nations, local planning authorities can hold relevant restrictions and the classification may depend on whether the system provides heating, cooling or both. A lawfully installed system may still have private-consent obligations. Where the position is uncertain, obtain advice from the relevant local planning authority, building-control body, landlord or freeholder and a suitably qualified property professional before committing to the installation.

Read the devolved planning position before applying house rules to a flat

In England, current Planning Portal guidance includes air-source heat pumps on qualifying blocks of flats, but applies special conditions including a smaller outdoor-unit volume and only the first qualifying installation on a block. Compliance with every condition, including the applicable MCS 020a planning standard, is required for that permitted-development route. In Wales, guidance effective from 1 June 2026 allows up to two air-source heat pumps at a detached home and one at a non-detached home, with a 1.5-cubic-metre outdoor-unit limit and heating or heating-and-cooling purpose, subject to MCS 020(a) and every siting and heritage condition. The guidance does not itself settle every flat or leasehold proposal.

Scottish Government Class 6H guidance covers dwellings including buildings containing flats, but limits the number on the same building and imposes location, designated-area, heating-or-hot-water and MCS conditions. Northern Ireland's Department for Infrastructure says its 2023 change allows domestic air-source heat pumps without an application only subject to conditions and limitations, including boundary and prescribed-noise requirements. These sources can change. Check the page date, the current national legislation or guidance and the local authority position; do not import an England threshold into Wales, Scotland or Northern Ireland.

Turn outdoor-unit sound and visual impact into evidence

Ask for the exact outdoor model's declared sound-power data, the selected operating configuration and a marked position relative to nearby habitable-room windows. The MCS 020a method considers assessment positions and installation effects; a generic product decibel in a brochure is not the completed project calculation. Hard courtyards, corners, balconies and light wells can reflect sound, while high-level or roof positions may need special access. Record mounts, vibration isolation, quiet-mode assumptions and how the unit can be serviced without unsafe access or trespass.

The DESNZ review found a low incidence of complaints in its evidence but linked complaints it did find to installation quality, including location and proximity. That supports careful siting; it is not a promise that a compliant unit will be inaudible or immune from nuisance concerns. The permission pack should include scaled photographs or drawings, dimensions including housing, colour and screening proposals that do not obstruct airflow, the acoustic evidence and the relevant neighbour relationship. Do not accept an unverified claim that a balcony or hidden courtyard automatically solves planning or sound.

Specify penetrations, refrigerant work and condensate before installation

A split air-to-air system needs refrigerant lines and an electrical route between indoor and outdoor equipment. An air-to-water system needs water, electrical and control connections and may involve wider plant. Show the diameter and position of every proposed penetration, the sealing and making-good method, any required fire or acoustic stopping and responsibility for hidden services. Work on refrigerant circuits must be handled by appropriately qualified professionals; a permission pack is not a DIY installation guide or proof of F-Gas competence.

Condensate needs a deliberate destination. Indoor cooling units and some outdoor operating conditions can produce water. The design should state whether it drains by gravity or pump, the route and gradient, access for cleaning, freeze or blockage precautions and the approved discharge point. It should not drip across a façade, balcony below, entrance, public path or neighbouring property. Ask who owns and maintains the route, how a failure will be contained and whether the freeholder requires a particular connection or visible-pipe treatment.

Do not let a heating proposal leave hot water unexplained

An air-to-water heat pump can be designed to serve a wet heating system and domestic hot water, but a flat needs credible space for the cylinder or alternative store, distribution pipework and safe servicing. The proposal should show daily hot-water demand, storage volume, heat-up strategy, backup or sterilisation arrangement and electrical load. If the building already has communal heating or hot water, establish what can legally and technically be disconnected, what charges remain and whether the proposed system affects shared risers or metering.

Air-to-air heat pumps deliver heat directly through fan-coil indoor units and can provide cooling, but they normally do not supply domestic hot water. Retaining an immersion cylinder, direct electric heater, heat network or another hot-water system changes both capital and running-cost comparisons. State the retained hot-water service explicitly rather than comparing an air-to-air quotation with a whole-home air-to-water project as though their scope were identical. Current grant treatment also depends on technology and scheme rules, so check the dated Grant Tracker instead of treating the word heat pump as proof of eligibility.

Build one reviewable permission pack before paying a deposit

Collect the equipment schedule, product datasheets, heating-or-cooling classification, room-by-room design information, outdoor-unit location, dimensions, mounting, sound calculation, visual evidence, pipe and cable route, condensate plan, electrical scope, penetrations, fire and acoustic stopping, maintenance access, installer credentials, insurance and warranty. Add the lease or tenancy question list, landlord or freeholder decision, planning and building-control responses where applicable, working hours, protection of common areas, making good, future removal and reinstatement responsibilities.

Use the CoolCompare Flat and Leasehold Permission Pack to organise those facts, then ask installers to quote the approved scope. If a permanent outdoor system cannot obtain a viable position or consent, reconsider the service rather than forcing the product. Shading, ventilation management, fans or a carefully vented portable air conditioner may address a cooling problem with less permanent fabric work, although window security, tenancy terms and safe drainage still matter. A building-wide communal option may be more appropriate where individual outdoor units cannot be accommodated, but it requires collective design and authority.

Decision checklist

Frequently asked questions