The hydrobox is a wall-mounted cabinet roughly the size of a boiler, or it can be built into a combined cylinder unit. It holds the heat exchanger, circulating pump, valves and controls. Outdoor units for split systems can be more compact than monobloc units of similar output, which helps where outdoor space is limited.
In Lanarkshire, a hydrobox often goes in an utility room or garage, with the cylinder alongside. Flats and terraces in Lanarkshire with a small yard or flat roof can suit a compact split outdoor unit. Installers covering Lanarkshire keep refrigerant routes neat and protected along the outside wall.
Who it suits
- Small yards, roofs or balconies that suit a more compact outdoor unit
- Houses with indoor wall space for a boiler-sized hydrobox
- Owners who would rather not use glycol or anti-freeze valves
- Homes where the outdoor unit must sit some distance from the plant space
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 Lanarkshire, 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.
Split system heat pumps prices in Lanarkshire
These are guide prices for Lanarkshire, 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 | £9,500–£12,500 |
| 2–3 bedroom terrace or semi | 5–7 kW | £10,500–£13,500 |
| 3 bedroom semi or small detached | 6–9 kW | £12,000–£15,500 |
| 4 bedroom detached | 8–12 kW | £14,000–£18,000 |
| 5+ bedroom or larger older house | 11–16 kW | £16,500–£22,500 |
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 Lanarkshire
We cover 13 towns in Lanarkshire for split system heat pumps. Each links to local guide prices and the grant position for Scotland.
| Town | Postcode district | Nearest town | Midwinter daylight |
|---|---|---|---|
| East Kilbride | G74 | Cambuslang | 7 h 00 min |
| Hamilton | ML3 | Motherwell | 7 h 00 min |
| Cumbernauld | G67 | Airdrie | 6 h 57 min |
| Coatbridge | ML5 | Airdrie | 6 h 59 min |
| Airdrie | ML6 | Coatbridge | 6 h 59 min |
| Motherwell | ML1 | Bellshill | 7 h 00 min |
| Rutherglen | G73 | Cambuslang | 6 h 59 min |
| Cambuslang | G73 | Rutherglen | 6 h 59 min |
| Wishaw | ML2 | Motherwell | 7 h 00 min |
| Bellshill | ML4 | Motherwell | 6 h 59 min |
| Carluke | ML8 | Wishaw | 7 h 00 min |
| Lanark | ML11 | Carluke | 7 h 01 min |
| Strathaven | ML10 | Hamilton | 7 h 01 min |
Split system heat pumps questions
How far apart can the outdoor unit and hydrobox be?
It depends on the model: each manufacturer sets a maximum refrigerant pipe length and height difference, and longer runs may need extra refrigerant. In practice a split system allows more flexibility than a monobloc's water pipes, so the outdoor unit can often sit on the far side of a house, on a flat roof or round a corner. The survey measures the actual route.
Do I need an F-gas engineer for a split heat pump?
Yes. Split systems usually use a fluorinated refrigerant such as R32, so installing, servicing or repairing the refrigerant circuit must by law be done by an F-gas certified engineer. That covers joining the refrigerant pipes, testing them for leaks and charging the system. Your quote sets out who carries out each part of the installation, including the refrigerant work.
How big is a hydrobox?
A hydrobox is typically about the size of a wall-mounted boiler, though sizes vary by make and model. It needs wall space near the cylinder with room around it for servicing and pipe connections. Some manufacturers combine the hydrobox and cylinder in a single floor-standing unit similar in size to a tall fridge-freezer, which can suit a utility room or garage.
Is a split system more efficient than a monobloc?
Not inherently. Efficiency depends far more on design, meaning correct sizing, low flow temperatures and good controls, than on whether the unit is split or monobloc. A split system can avoid the heat loss and glycol of a long outdoor water run, which helps in certain layouts. The survey estimates seasonal efficiency for the specific units proposed, so you can compare like for like.