What happens during an air source heat pump survey in your home?

What to know first

A technical heat pump survey should turn information about your home into a property-specific design, not simply support a sales estimate.

A full survey is the evidence-gathering stage for the proposed system. Some calculations may be completed afterwards, but the final design should be based on the property rather than a generic house or the output of the old boiler.

The visit does not guarantee suitability, planning status, network approval or scheme eligibility. Those conclusions depend on the completed design and, where relevant, decisions by other organisations.

Is the visit a technical survey or a sales appointment?

Ask this before anyone arrives. Under the Renewable Energy Consumer Code, a member must make clear whether a visit includes a technical site survey. If it charges, it must explain the refund conditions and provide a written report.

An initial appointment may support an indicative proposal. A technical survey validates measurements, records assumptions and identifies work needed for the final design. Ask who will calculate the design, which standard they will follow and which documents are included.

Good to know

A survey fee is not automatically a concern. Check the scope, written output and whether any of the fee is credited or refunded.

What happens during the heat pump survey?

1. The surveyor reviews the home

The surveyor may start with the Energy Performance Certificate, plans and evidence of insulation or alterations. They should understand the existing heating and hot-water system, rooms that are difficult to heat, and planned building work that could change heat loss.

An Energy Performance Certificate is useful background, but it contains assumptions. Insulation certificates, drawings or loft access can help replace an assumption with property-specific evidence.

2. Every heated space is measured

The surveyor records room dimensions, windows, external doors and the walls, floors and ceilings or roofs around each space. They note whether adjoining areas are heated, unheated or outside, plus ventilation such as extract fans, chimneys and open flues. Halls and landings still matter even without a radiator.

MCS Heat Load Calculator documentation, accessed on 27 July 2026, states:

3. The fabric becomes a heat-loss calculation

“Heat loss” is the rate at which the home loses heat on a cold design day. It is estimated for each room and the whole property, usually in watts or kilowatts.

The calculation uses the size and construction of walls, floors, roofs, windows and doors. It also allows for ventilation, air leakage, room temperature and local winter design conditions. Where construction is hidden, the report should state the assumption rather than present it as measured fact.

Room-by-room results help the designer choose the heat pump capacity and the heat output needed from radiators or underfloor heating in each space.

4. Emitters and pipework are checked

An “emitter” releases heat into a room, such as a radiator or underfloor heating. Its output at the proposed design flow temperature should be compared with the room’s heat loss. Flow temperature is the temperature of the water leaving the heat pump for the heating system.

Some radiators may stay; others may need enlargement, an addition or relocation. The survey should also examine pipe sizes and routes, pumps, controls and any underfloor-heating manifold.

Microbore pipework is not an automatic rejection. It needs a flow and pressure assessment, and restrictive runs may need alteration.

Expert insight

“A credible proposal links each room’s heat loss, emitter output at the proposed flow temperature and the pipework’s ability to move enough water.”

Giles Crosse

Energy Editor

Experienced editor, journalist and communications consultant specialising in consumer energy and low carbon technologies.

• Editor and campaign author for Shell, EDF Energy and Good Energy.
• Consultant to the United Nations and contributor to the World Economic Forum.
• Journalist for Reuters, the BBC, The Economist and The Guardian.

More about Giles Crosse

5. Hot water and indoor equipment are assessed

For an air-to-water system, the survey should record the position, type and size of any hot-water cylinder, the cold-water supply and relevant discharge pipework. The proposed storage and reheat arrangement should reflect likely household demand.

The surveyor should identify space and access for the cylinder and any indoor hydraulic equipment, pumps or valves required by the chosen design.

6. The electrical supply is reviewed

The survey should identify the consumer unit, space for a new circuit, the main incoming fuse or cut-out, meter, maximum demand and whether the supply may be looped. The heat pump, immersion heater and other major electric loads must be considered together.

A qualified electrician may need to confirm the electrical design. The distribution network operator, which runs the local electricity network, may allow connection followed by notification or require approval first. The installer should explain the route and who will handle it.

7. The outdoor position is tested

The surveyor should identify a practical unit position and pipe and cable routes. The location needs an early noise assessment and must suit the selected product’s installation and maintenance instructions.

Planning rules differ across the UK. Listed buildings, conservation areas, flats, local restrictions and the number, size or position of units can change the answer.

Leasehold or shared properties may also require consent from a freeholder, landlord or managing agent.

Good to know

“Permitted development” is conditional, not automatic. Ask who will check planning, building-regulations and property-consent requirements.

The findings may require input from an electrician, distribution network operator, planning authority, conservation officer or property manager.

What should you receive after the survey?

Documents arrive at different stages. The table is a starting point; the contract should state exactly what will be provided.

The Renewable Energy Consumer Code Version 8, which remains listed in the 21 July 2026 Boiler Upgrade Scheme notice, says:

Its code requires an itemised quotation, excluded work and site conditions that could create extra charges to be set out before the contract.

Survey documents are separate from installation handover documents. After commissioning, the installer should provide test records, operating instructions, certificates and guarantees, including the MCS certificate where relevant.

What if the design or price changes?

A survey can reveal greater heat loss, an unsuitable cylinder, electrical work, a planning issue or more radiator and pipework changes than expected. That is one reason to survey before installation.

For a Renewable Energy Consumer Code member, design or quotation changes should be explained in writing. If the site is unsuitable, or installation requires a materially different form or place, the code sets out cancellation and refund protections. Keep the report, quotation and correspondence.

Practical warning signs, inferred from these requirements, include omitting rooms, giving no written assumptions, declaring all radiators suitable without an emitter schedule, ignoring electrics or outdoor siting, and seeking a signature before providing property-specific performance information and an itemised quote.

Key takeaways

• A technical survey should produce property-specific evidence, not just a sales estimate.

• Every heated space should feed into the room-by-room heat-loss calculation.

• Emitters, pipework, hot water, electrics and outdoor siting affect the design.

• Important assumptions should be recorded.

• A paid survey should come with a written report.

• Planning, network and scheme requirements should be rechecked before installation; sources were checked on 27 July 2026.

Frequently asked questions