This suits homes where changing radiators is hard: period and listed properties with cast-iron radiators or fragile finishes, homes with microbore pipework that is difficult to replace, and rooms with no space for a larger radiator. Many of these units use R290 (propane), a natural refrigerant that makes higher water temperatures more achievable than some earlier refrigerants did.
Older homes around Wiltshire often need a discreet unit position, such as a rear courtyard, which the survey looks for first. A survey in Wiltshire can compare a high-temperature unit with upsizing a few radiators, for homes anywhere in Wiltshire. In Wiltshire, rooms with large bay windows are often the ones where radiator output is checked most carefully.
Who it suits
- Rooms with no wall space for a larger radiator
- Period and listed homes where the radiators are part of the character
- Older homes where insulation improvements are limited
- Owners who want fewer changes inside the house
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.
High-temperature heat pumps prices in Wiltshire
The ranges below are typical installed prices for homes in Wiltshire, including VAT. A survey sets the exact figure, because two similar-looking houses in Wiltshire can need quite different radiators and pipework.
| Home | Typical size | Installed guide price | After £7,500 grant |
|---|---|---|---|
| 1–2 bedroom flat or small terrace | 4–5 kW | £9,600–£12,650 | £2,100–£5,150 |
| 2–3 bedroom terrace or semi | 5–7 kW | £10,600–£13,650 | £3,100–£6,150 |
| 3 bedroom semi or small detached | 6–9 kW | £12,100–£15,650 | £4,600–£8,150 |
| 4 bedroom detached | 8–12 kW | £14,150–£18,200 | £6,650–£10,700 |
| 5+ bedroom or larger older house | 11–16 kW | £16,650–£22,750 | £9,150–£15,250 |
Installed, inc VAT: unit, cylinder, controls, minor pipework and commissioning. A high-temperature unit typically adds £1,500–£3,000.
Towns we cover in Wiltshire
We cover 12 towns in Wiltshire for high-temperature heat pumps. Each links to local guide prices and the grant position for England.
| Town | Postcode district | Nearest town | Midwinter daylight |
|---|---|---|---|
| Swindon | SN1 | Marlborough | 7 h 49 min |
| Salisbury | SP1 | Amesbury | 7 h 54 min |
| Trowbridge | BA14 | Bradford-on-Avon | 7 h 51 min |
| Chippenham | SN15 | Corsham | 7 h 50 min |
| Melksham | SN12 | Corsham | 7 h 51 min |
| Warminster | BA12 | Trowbridge | 7 h 53 min |
| Calne | SN11 | Chippenham | 7 h 50 min |
| Devizes | SN10 | Calne | 7 h 51 min |
| Amesbury | SP4 | Salisbury | 7 h 53 min |
| Bradford-on-Avon | BA15 | Trowbridge | 7 h 51 min |
| Corsham | SN13 | Chippenham | 7 h 50 min |
| Marlborough | SN8 | Swindon | 7 h 50 min |
High-temperature heat pumps questions
Are high-temperature heat pumps less efficient?
Yes, when they run hot. Every heat pump uses more electricity per unit of heat as the flow temperature rises, so a unit running at 70°C is less efficient than one running at 45°C. With weather compensation it runs cooler for much of the year, which narrows the gap. The design aims to keep the maximum temperature as low as your radiators allow.
Can a heat pump work with my existing radiators?
Often, yes, especially with a high-temperature unit. Standard heat pumps run most efficiently at 35–50°C, so some radiators may be too small at those temperatures. A high-temperature unit can run at around 65–75°C, so existing radiators can usually heat rooms much as they do with a boiler, at a cost in efficiency. The survey checks every radiator against its room's heat loss.
Do I still need a hot water cylinder?
Yes. Like other air-to-water heat pumps, a high-temperature unit heats a stored cylinder rather than supplying hot water on demand. Its higher output temperature can help the cylinder reach the temperature needed for its periodic legionella cycle with less reliance on the immersion heater. The cylinder is sized for your household at survey.
Why do many high-temperature units use R290?
R290 is propane, a natural refrigerant with a very low global warming impact. Its properties make higher water temperatures more achievable than with some earlier refrigerants. Because it is flammable, manufacturers set clearance zones around the outdoor unit from windows, doors, drains and other openings, which the survey uses when choosing a position.