Explainer

Air to air heat pumps: cost, grant and what to check first

A practical guide to what air to air heat pumps are, how they differ from wet ASHP systems, what they cost, and what a good site record needs before decisions are made.

GOV.UK now lists a £2,500 BUS grant for eligible air-to-air heat pumps, with approved grant values effective from 28 April 2026. That makes the survey route more important, not less. · 4 min read

ASHP survey reports Heat pump survey route

What they are

Air-to-air is not the same survey conversation as wet ASHP retrofit

System type

Warm air instead of wet emitters

Air-to-air systems provide space heating and, in many cases, cooling through indoor units. They do not use the same emitter and hot-water route as wet ASHP systems.

Design questions

Different early constraints

Room placement, line routes, condensate handling, external unit position, and electrical supply often become the first questions rather than radiator and cylinder layout.

Why it matters

Avoid wrong assumptions

Teams lose time when air-to-air, wet ASHP, and broad heat pump terminology get mixed together. Start on the right route and the survey record becomes easier to use.

Cost

Air to air heat pumps cost usually moves with layout, electrical work, and access

No single number

There is no one official installed cost for air to air heat pumps. The price usually moves with the number of indoor units, route length, electrical work, access, and whether the property needs extra making-good.

Grant effect

For eligible domestic jobs, the BUS route now lists air-to-air systems with a £2,500 grant. That changes the net number, but it does not remove the need for a clear survey.

Why surveys matter

People often price the headline kit first and discover the real cost later. Indoor unit positions, condensate routes, cable runs, and awkward access are usually what shift the quote.

Use the grant as a current benchmark. Use the survey to stop the job being priced on the wrong assumptions.

What to check first

The first site questions are practical, not theoretical

Layout

Indoor unit locations and coverage zones
External unit siting and route length
Wall penetrations, condensate paths, and access

Electrical

Supply capacity and consumer unit context
Isolation and practical install constraints
Any distribution-board or cable-route issues

Compliance

Planning-sensitive siting questions
Noise-sensitive positions and neighbour context
Whether the broader EPC or fabric picture still matters

ASHP survey reports Air to air heat pumps cost £2,500 grant update Installer checklist ASHP vs air-to-air ASHP survey reports Energy performance certificate guide

Official reference points

What the 2026 BUS updates say

DESNZ position

The current GOV.UK BUS pages now list £2,500 towards an air-to-air heat pump, alongside the other live grant values.

Ofgem guidance

Ofgem’s March 2026 draft property-owner and installer guidance says those changes are expected to apply to applications properly made on or after 28 April 2026.

Practical inference

That eligibility does not make air-to-air the same as air-to-water. The survey still has to answer room coverage, indoor units, route length, condensate, controls, noise, and electrical context clearly.

Sources checked on 27 May 2026: GOV.UK Boiler Upgrade Scheme, GOV.UK approved grant categories, and Ofgem BUS installer guidance v5 update summary. The third card above is an inference from those rules plus the system type.