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.
Homeowners in Northamptonshire thinking about insulation work can use the survey to see how it would change their heat pump size. For Northamptonshire homes with extensions or loft conversions, each part of the house is assessed on its own construction. Houses in Northamptonshire built in different eras can need very different heat pump sizes, which is why each is calculated room by room.
Who it suits
- Landlords comparing properties before deciding where to switch first
- Self-builders and architects who need emitter and system sizes early
- 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
Homes in Northamptonshire can use the Boiler Upgrade Scheme, which takes £7,500 off the cost of an air source heat pump when it replaces fossil-fuel or electric heating. Replacing oil or LPG heating qualifies for £9,000 for installations from 21 July 2026 to 31 March 2027, and air-to-air systems for £2,500. The MCS-certified installer named in your quote applies for the grant and deducts it from the price.
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 Northamptonshire
The ranges below are typical installed prices for homes in Northamptonshire, including VAT. A survey sets the exact figure, because two similar-looking houses in Northamptonshire 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 | £150–£400 |
Inc VAT. A stand-alone report is for homeowners who want the design without an installation quote.
Towns we cover in Northamptonshire
We cover 10 towns in Northamptonshire for heat loss surveys. Each links to local guide prices and the grant position for England.
| Town | Postcode district | Nearest town | Midwinter daylight |
|---|---|---|---|
| Northampton | NN1 | Wellingborough | 7 h 42 min |
| Corby | NN17 | Desborough | 7 h 39 min |
| Kettering | NN16 | Desborough | 7 h 40 min |
| Wellingborough | NN8 | Rushden | 7 h 41 min |
| Rushden | NN10 | Wellingborough | 7 h 41 min |
| Daventry | NN11 | Towcester | 7 h 42 min |
| Brackley | NN13 | Towcester | 7 h 44 min |
| Desborough | LE16 | Kettering | 7 h 40 min |
| Oundle | PE8 | Corby | 7 h 39 min |
| Towcester | NN12 | Northampton | 7 h 43 min |
Heat loss surveys questions
Can I use the heat loss report to get other quotes?
Yes. A stand-alone heat loss report is yours to use, including sharing it with other installers so their quotes are based on the same figures. Comparing quotes like for like makes it easier to see differences in equipment, radiator upgrades and workmanship terms. The report states the assumptions used wherever construction could not be confirmed.
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.
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.
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.