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.
For Buckinghamshire homes with extensions or loft conversions, each part of the house is assessed on its own construction. A surveyor visits your home to measure each room, window and wall before any heat pump is sized. Houses in Buckinghamshire 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
- Landlords comparing properties before deciding where to switch first
- Homes with an existing heat pump that seems undersized or expensive to run
- 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.
There is no VAT on installing a heat pump anywhere in the UK until 31 March 2027. In England most houses can have an air source heat pump under permitted development, provided the unit meets the MCS noise and siting standards; the old 1 m boundary limit was removed on 29 May 2025. We flag listed buildings, flats and sensitive conservation-area positions at survey.
Heat loss survey prices in Buckinghamshire
The ranges below are typical installed prices for homes in Buckinghamshire, including VAT. A survey sets the exact figure, because two similar-looking houses in Buckinghamshire can need quite different radiators and pipework.
| Survey | Guide price |
|---|---|
| Home survey and heat loss calculation with an installation quote | Free |
| Stand-alone heat loss survey and report | £160–£420 |
Inc VAT. A stand-alone report is for homeowners who want the design without an installation quote.
Towns we cover in Buckinghamshire
We cover 13 towns in Buckinghamshire for heat loss surveys. Each links to local guide prices and the grant position for England.
| Town | Postcode district | Nearest town | Midwinter daylight |
|---|---|---|---|
| Milton Keynes | MK9 | Bletchley | 7 h 44 min |
| High Wycombe | HP11 | Marlow | 7 h 48 min |
| Aylesbury | HP20 | Princes Risborough | 7 h 46 min |
| Bletchley | MK2 | Milton Keynes | 7 h 44 min |
| Amersham | HP7 | Chesham | 7 h 48 min |
| Chesham | HP5 | Amersham | 7 h 48 min |
| Gerrards Cross | SL9 | Chalfont St Peter | 7 h 49 min |
| Chalfont St Peter | SL9 | Gerrards Cross | 7 h 48 min |
| Marlow | SL7 | High Wycombe | 7 h 49 min |
| Beaconsfield | HP9 | Chalfont St Peter | 7 h 48 min |
| Buckingham | MK18 | Brackley | 7 h 44 min |
| Olney | MK46 | Milton Keynes | 7 h 43 min |
| Princes Risborough | HP27 | Aylesbury | 7 h 47 min |
Heat loss surveys questions
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.
Why can't you size the heat pump from my boiler?
Boilers are often much larger than a home's real heat loss, because they are sized for fast hot water and quick warm-ups. Matching a heat pump to the boiler's output usually means an oversized unit that costs more and switches on and off too often. A room-by-room calculation finds the actual heat demand, which is what the heat pump needs to meet.
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.
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.