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. Houses in County Durham built in different eras can need very different heat pump sizes, which is why each is calculated room by room. For County Durham homes with extensions or loft conversions, each part of the house is assessed on its own construction.
Who it suits
- Anyone getting a heat pump quote, as the first step
- Landlords comparing properties before deciding where to switch first
- 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
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 County Durham
The ranges below are typical installed prices for homes in County Durham, including VAT. A survey sets the exact figure, because two similar-looking houses in County Durham 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–£390 |
Inc VAT. A stand-alone report is for homeowners who want the design without an installation quote.
Towns we cover in County Durham
We cover 14 towns in County Durham for heat loss surveys. Each links to local guide prices and the grant position for England.
| Town | Postcode district | Nearest town | Midwinter daylight |
|---|---|---|---|
| Darlington | DL1 | Newton Aycliffe | 7 h 16 min |
| Hartlepool | TS26 | Peterlee | 7 h 14 min |
| Stockton-on-Tees | TS18 | Billingham | 7 h 15 min |
| Durham | DH1 | Chester-le-Street | 7 h 13 min |
| Chester-le-Street | DH2 | Stanley | 7 h 12 min |
| Billingham | TS23 | Stockton-on-Tees | 7 h 15 min |
| Stanley | DH9 | Chester-le-Street | 7 h 12 min |
| Consett | DH8 | Stanley | 7 h 12 min |
| Newton Aycliffe | DL5 | Bishop Auckland | 7 h 15 min |
| Bishop Auckland | DL14 | Newton Aycliffe | 7 h 14 min |
| Seaham | SR7 | Peterlee | 7 h 12 min |
| Peterlee | SR8 | Seaham | 7 h 13 min |
| Barnard Castle | DL12 | Bishop Auckland | 7 h 16 min |
| Sedgefield | TS21 | Newton Aycliffe | 7 h 14 min |
Heat loss surveys questions
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.
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.
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.