The trade-off is efficiency. The hotter the water a heat pump makes, the more electricity it needs for each unit of heat, so a system running at 65°C has a lower seasonal efficiency than one running at 45°C. Good design still matters: weather compensation runs the unit cooler on mild days and only raises the temperature in the coldest weather, which keeps running costs down across the year.
Older homes around the Highlands and Islands often need a discreet unit position, such as a rear courtyard, which the survey looks for first. Period houses in the Highlands and Islands with original cast-iron radiators may suit a high-temperature unit that works with them. For older the Highlands and Islands homes with microbore pipework, a higher flow temperature can avoid lifting floors to replace pipes.
Who it suits
- Homes with microbore pipework that would be disruptive to replace
- Rooms with no wall space for a larger radiator
- Older homes where insulation improvements are limited
- Period and listed homes where the radiators are part of the character
Grants and rules for heat pumps in Scotland
The Boiler Upgrade Scheme does not apply in Scotland. Instead, homeowners in the Highlands and Islands can apply to Home Energy Scotland for a grant of up to £7,500 towards a heat pump, with up to £1,500 more for eligible rural and island homes, plus an optional interest-free loan of up to £7,500. You need a written funding offer before any work starts.
Installing heat pumps is zero-rated for VAT across the UK until 31 March 2027. Scotland has its own permitted development rules for air source heat pumps and its own building standards, so we confirm what applies to your property at survey.
High-temperature heat pumps prices in the Highlands and Islands
The ranges below are typical installed prices for homes in the Highlands and Islands, including VAT. A survey sets the exact figure, because two similar-looking houses in the Highlands and Islands can need quite different radiators and pipework.
| Home | Typical size | Installed guide price |
|---|---|---|
| 1–2 bedroom flat or small terrace | 4–5 kW | £10,650–£14,000 |
| 2–3 bedroom terrace or semi | 5–7 kW | £11,750–£15,100 |
| 3 bedroom semi or small detached | 6–9 kW | £13,450–£17,350 |
| 4 bedroom detached | 8–12 kW | £15,700–£20,150 |
| 5+ bedroom or larger older house | 11–16 kW | £18,500–£25,200 |
Installed, inc VAT: unit, cylinder, controls, minor pipework and commissioning. A high-temperature unit typically adds £1,500–£3,000. In Scotland, Home Energy Scotland grants of up to £7,500 and interest-free loans may reduce the cost.
Towns we cover in the Highlands and Islands
We cover 12 towns in the Highlands and Islands for high-temperature heat pumps. Each links to local guide prices and the grant position for Scotland.
| Town | Postcode district | Nearest town | Midwinter daylight |
|---|---|---|---|
| Inverness | IV1 | Dingwall | 6 h 35 min |
| Fort William | PH33 | Oban | 6 h 45 min |
| Aviemore | PH22 | Inverness | 6 h 40 min |
| Dingwall | IV15 | Inverness | 6 h 34 min |
| Kirkwall | KW15 | – | 6 h 11 min |
| Lerwick | ZE1 | – | 5 h 49 min |
| Nairn | IV12 | Forres | 6 h 34 min |
| Portree | IV51 | – | 6 h 36 min |
| Stornoway | HS1 | – | 6 h 24 min |
| Thurso | KW14 | Wick | 6 h 17 min |
| Ullapool | IV26 | Dingwall | 6 h 29 min |
| Wick | KW1 | Thurso | 6 h 20 min |
High-temperature heat pumps questions
Are high-temperature heat pumps eligible for the grant?
In England and Wales, yes. A high-temperature unit is an air-to-water heat pump, so eligible owners of existing homes can receive £7,500 through the Boiler Upgrade Scheme, or £9,000 when replacing oil or LPG within the published dates. Scotland's Home Energy Scotland funding has its own conditions, and Northern Ireland has no dedicated homeowner grant at present.
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.
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.
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.