The main survey stages
| Stage | What happens | Why it matters |
|---|---|---|
| Scope confirmation | Postcode, property type, survey route, heat loss scope, EPC need, and installer requirements are confirmed before the visit. | The surveyor needs to know whether the job is ASHP-only or part of a wider heat loss, EPC, or solar route. |
| External siting | Potential outdoor unit positions, access, clearance, boundaries, windows, surfaces, and visible constraints are recorded. | The unit location affects sound checks, pipe runs, maintenance access, and whether the proposal is practical. |
| Plant and electrical context | Cylinder area, existing heating system, meter, consumer unit, isolator route, and visible electrical context are captured where required. | The heating and electrical reality often decides whether a quote is clean or needs revision. |
| Room and fabric evidence | Room measurements, floor plan context, emitter notes, insulation clues, and fabric assumptions are captured if heat loss work is in scope. | Heat pump sizing depends on the rooms and fabric assumptions, not only on the old boiler size. |
| Report handover | Photos, notes, measurements, constraints, and route details are put into a report the installer and designer can work from. | A clear report reduces callbacks and makes the next decision easier to defend. |
What the surveyor is trying to avoid
The survey is there to catch the details that normally create rework: a unit location that cannot work, a sound path that was not considered, a long cable route, an awkward cylinder change, missing room measurements, weak heat loss inputs, or photos that do not show the decision points clearly.
That is why the best ASHP survey packs do not stop at one external photo. They show the proposed unit area, the route back to the plant, nearby windows and boundaries, consumer unit context, plant-room constraints, and the room evidence needed by the design team.
How MCS 020(a) sound inputs fit in
An air source heat pump survey should capture the site details needed for sound checks, but the final responsibility for the calculation and design decision sits with the competent installer or designer. The survey evidence should make those decisions easier by showing the proposed unit position, relevant windows, boundaries, surfaces, and any obvious constraints around the property.
For the broader checklist, use the air source heat pump survey page. For pricing and report proof, use the ASHP survey page. For room-by-room inputs, use the heat loss calculations guide.