The trade-off is that the pipes between the outdoor unit and the house carry water, so they must be protected from freezing. That is done with glycol (an anti-freeze) in the system or with anti-freeze valves that release water from the outdoor pipework if it nears freezing, for example during a power cut in cold weather. Keeping the outdoor pipe run short and well insulated also helps efficiency.
A survey in the Highlands and Islands checks the unit position, pipe route and clearance zones together for homes across the Highlands and Islands. Bungalows in the Highlands and Islands often let the unit sit right beside the plant cupboard, keeping water pipes short. Houses in the Highlands and Islands with a rear wall close to the cylinder location usually suit a monobloc unit with a short pipe run.
Who it suits
- Houses and bungalows with outdoor space close to where pipes enter the home
- Households that want to keep refrigerant work out of routine servicing
- Homes where the unit can sit within a short pipe run of the cylinder
- Owners who want the simplest installation, with no indoor refrigerant
Grants and rules for heat pumps in Scotland
In Scotland, heat pump funding comes through Home Energy Scotland rather than the Boiler Upgrade Scheme: a grant of up to £7,500 (up to £1,500 extra for eligible rural and island homes) and an optional interest-free loan of up to £7,500. For a home in the Highlands and Islands, apply and receive the written offer before the installation date is fixed.
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.
Monobloc heat pumps prices in the Highlands and Islands
These are guide prices for the Highlands and Islands, installed and including VAT. Your final price is fixed in a written quote after the survey and depends on the heat loss of the house, the radiators that need changing and where the unit goes.
| 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. 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 monobloc 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 |
Monobloc heat pumps questions
What is the difference between monobloc and split heat pumps?
A monobloc unit holds all of its refrigerant in the outdoor unit and sends heated water into the house. A split system has an outdoor unit and an indoor unit called a hydrobox, connected by refrigerant pipes, with heat passed to water indoors. Monobloc installs are simpler; splits avoid outdoor water pipes but need an F-gas certified engineer for the refrigerant work. Our monobloc vs split guide compares them.
How far can a monobloc unit be from the house?
Usually as close as practical, because water pipes outside lose heat and need frost protection. Manufacturers set limits on pipe length and size, and longer runs need larger, better-insulated pipes. Most homes site the unit against or near an outside wall close to where the pipes enter. If the only good position is far from the house, a split system may suit better.
Are monobloc heat pumps covered by grants?
Yes. Monobloc units are air-to-water heat pumps, so in England and Wales they are covered by the Boiler Upgrade Scheme grant of £7,500 for eligible homes, or £9,000 when replacing oil or LPG heating within the published dates. In Scotland, Home Energy Scotland funding requires an MCS-certified installer and products. There is no dedicated homeowner heat pump grant in Northern Ireland at present.
Do monobloc heat pumps need an F-gas engineer?
For a typical installation no refrigerant work is needed on site, because the refrigerant circuit is sealed in the outdoor unit at the factory. That is one reason monobloc installs are simpler. If the sealed circuit ever develops a fault or leak, any repair to it must be done by an F-gas certified engineer, as with every refrigerant system.