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 Powys and the wider Powys come from local cold-weather data, not a national average. For Powys homes with extensions or loft conversions, each part of the house is assessed on its own construction.
Who it suits
- Homeowners planning insulation or building work who want to know the effect on heat demand
- Anyone getting a heat pump quote, as the first step
- Self-builders and architects who need emitter and system sizes early
- Landlords comparing properties before deciding where to switch first
Grants and rules for heat pumps in Wales
Homes in Powys can use the Boiler Upgrade Scheme, which applies in Wales as well as England: £7,500 towards an air source heat pump, or £9,000 when it replaces oil or LPG heating for installations from 21 July 2026 to 31 March 2027. The MCS-certified installer named in your quote applies and deducts the grant.
There is no VAT on installing a heat pump anywhere in the UK, Wales included, until 31 March 2027. Planning rules for heat pumps in Wales are set by the Welsh Government and differ from England's, so the surveyor checks the unit position against them.
Heat loss survey prices in Powys
The ranges below are typical installed prices for homes in Powys, including VAT. A survey sets the exact figure, because two similar-looking houses in Powys 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 Powys
We cover 10 towns in Powys for heat loss surveys. Each links to local guide prices and the grant position for Wales.
| Town | Postcode district | Nearest town | Midwinter daylight |
|---|---|---|---|
| Brecon | LD3 | Crickhowell | 7 h 45 min |
| Builth Wells | LD2 | Llandrindod Wells | 7 h 43 min |
| Crickhowell | NP8 | Abergavenny | 7 h 46 min |
| Hay-on-Wye | HR3 | Builth Wells | 7 h 44 min |
| Knighton | LD7 | Newtown | 7 h 41 min |
| Llandrindod Wells | LD1 | Builth Wells | 7 h 42 min |
| Machynlleth | SY20 | Dolgellau | 7 h 38 min |
| Newtown | SY16 | Welshpool | 7 h 39 min |
| Welshpool | SY21 | Newtown | 7 h 37 min |
| Ystradgynlais | SA9 | Pontardawe | 7 h 47 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.
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.
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.