Getting the size right matters. An undersized heat pump struggles in cold weather, while an oversized one costs more to buy and can switch on and off frequently, which wastes energy and wears components. Sizing from a rule of thumb, or simply matching the old boiler's output, is a common cause of poorly performing systems. A measured, room-by-room design avoids both problems and shows the reasoning behind every figure.
A surveyor visits your home to measure each room, window and wall before any heat pump is sized. Design outdoor temperatures for Dorset and the wider Dorset come from local cold-weather data, not a national average. Houses in Dorset built in different eras can need very different heat pump sizes, which is why each is calculated room by room.
Who it suits
- Homeowners planning insulation or building work who want to know the effect on heat demand
- Homes with an existing heat pump that seems undersized or expensive to run
- Self-builders and architects who need emitter and system sizes early
- Anyone getting a heat pump quote, as the first step
Grants and rules for heat pumps in England
In England the Boiler Upgrade Scheme gives £7,500 towards an air source heat pump (£9,000 if it replaces oil or LPG, from 21 July 2026 to 31 March 2027), and since 28 April 2026 a valid EPC is no longer needed. The grant is applied for by the MCS-certified installer and shown as a deduction on your quote.
Installing heat pumps is zero-rated for VAT across the UK until 31 March 2027. Since 29 May 2025, permitted development in England allows up to two air source heat pumps on a house, each up to 1.5 m³, with no blanket 1 m boundary rule — the installation must still meet the MCS planning standards, including the noise check. Listed buildings, flats and some conservation-area positions need extra consent, which we check at survey.
Heat loss survey prices in Dorset
These are guide prices for Dorset, installed and including VAT. Your final price is fixed in a written quote after the survey and depends on the heat loss of the house, the radiators that need changing and where the unit goes.
| Survey | Guide price |
|---|---|
| Home survey and heat loss calculation with an installation quote | Free |
| Stand-alone heat loss survey and report | £150–£400 |
Inc VAT. A stand-alone report is for homeowners who want the design without an installation quote.
Towns we cover in Dorset
We cover 12 towns in Dorset for heat loss surveys. Each links to local guide prices and the grant position for England.
| Town | Postcode district | Nearest town | Midwinter daylight |
|---|---|---|---|
| Bournemouth | BH2 | Christchurch | 7 h 57 min |
| Poole | BH15 | Bournemouth | 7 h 57 min |
| Weymouth | DT4 | Dorchester | 7 h 58 min |
| Christchurch | BH6 | Bournemouth | 7 h 57 min |
| Ferndown | BH22 | Wimborne Minster | 7 h 56 min |
| Dorchester | DT1 | Weymouth | 7 h 57 min |
| Wimborne Minster | BH18 | Ferndown | 7 h 57 min |
| Blandford Forum | DT11 | Wimborne Minster | 7 h 56 min |
| Bridport | DT6 | Dorchester | 7 h 57 min |
| Sherborne | DT9 | Yeovil | 7 h 55 min |
| Swanage | BH19 | Poole | 7 h 58 min |
| Wareham | BH20 | Poole | 7 h 58 min |
Heat loss surveys questions
What is a design flow temperature?
The design flow temperature is the temperature of the water sent to your radiators or underfloor heating on the coldest design day. Heat pumps are more efficient at lower flow temperatures, typically around 35–50°C. Choosing it is a balance: a lower figure improves efficiency but can mean larger radiators in some rooms, so the design shows both.
How long does a heat loss survey take?
A typical survey takes 1–3 hours on site, depending on the size and complexity of the home. Larger or older houses with mixed construction, extensions or many rooms take longer. The calculations and design are completed afterwards, and the results are included in your quote or stand-alone report.
Will the survey check noise from the outdoor unit?
Yes. The surveyor identifies possible positions for the outdoor unit and carries out the MCS noise assessment, which estimates the sound level at the nearest neighbouring window from the unit's sound power level, distance and any barriers. In England, meeting the MCS planning standards is one of the conditions for permitted development. Wales, Scotland and Northern Ireland have their own rules, which we check.
Is the heat loss survey free?
Yes, for installation enquiries the home survey and heat loss calculation are free, and the results form the basis of your written quote. If you only want the calculation and report, for example for building plans or comparing quotes, a stand-alone heat loss survey has a guide price of £150–£400, including VAT. We confirm which applies when you book.