Because the refrigerant pipes are joined and charged on site, and split systems usually use a fluorinated refrigerant such as R32, the refrigerant work must by law be done by an F-gas certified engineer. That makes installation a little more involved than a monobloc, and any later repair to the refrigerant circuit also needs F-gas certified work. In return, a split system copes better with long or awkward routes between the outdoor unit and the house, within the limits the manufacturer sets.
Properties on exposed sites around Dorset can avoid outdoor water pipes altogether with a split system. In Dorset, a hydrobox often goes in an utility room or garage, with the cylinder alongside. In Dorset homes where the clearest unit position is away from the plant cupboard, a split system allows a longer route indoors.
Who it suits
- Exposed or frost-prone sites where outdoor water pipes would be a risk
- Owners who would rather not use glycol or anti-freeze valves
- Small yards, roofs or balconies that suit a more compact outdoor unit
- Houses with indoor wall space for a boiler-sized hydrobox
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.
There is no VAT on installing a heat pump anywhere in the UK until 31 March 2027. In England most houses can have an air source heat pump under permitted development, provided the unit meets the MCS noise and siting standards; the old 1 m boundary limit was removed on 29 May 2025. We flag listed buildings, flats and sensitive conservation-area positions at survey.
Split system heat pumps prices in Dorset
The ranges below are typical installed prices for homes in Dorset, including VAT. A survey sets the exact figure, because two similar-looking houses in Dorset 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.
Towns we cover in Dorset
We cover 12 towns in Dorset for split system heat pumps. Each links to local guide prices and the grant position for England.
| Town | Postcode district | Nearest town | Midwinter daylight |
|---|---|---|---|
| Bournemouth | BH2 | Christchurch | 7 h 57 min |
| Poole | BH15 | Bournemouth | 7 h 57 min |
| Weymouth | DT4 | Dorchester | 7 h 58 min |
| Christchurch | BH6 | Bournemouth | 7 h 57 min |
| Ferndown | BH22 | Wimborne Minster | 7 h 56 min |
| Dorchester | DT1 | Weymouth | 7 h 57 min |
| Wimborne Minster | BH18 | Ferndown | 7 h 57 min |
| Blandford Forum | DT11 | Wimborne Minster | 7 h 56 min |
| Bridport | DT6 | Dorchester | 7 h 57 min |
| Sherborne | DT9 | Yeovil | 7 h 55 min |
| Swanage | BH19 | Poole | 7 h 58 min |
| Wareham | BH20 | Poole | 7 h 58 min |
Split system heat pumps questions
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.
Can a split system replace my combi boiler?
Yes, but like any air-to-water heat pump it needs a hot water cylinder, because it does not heat water instantly. The hydrobox can sometimes go where the combi was, with the cylinder in a cupboard, utility room or garage. Integrated units combining both are useful where one larger space is available. The survey checks what fits before the design is finalised.
Is a split system eligible for the Boiler Upgrade Scheme?
Yes. A split air-to-water heat pump counts as an air source heat pump under the scheme, so in England and Wales eligible owners of existing homes can receive £7,500, or £9,000 when replacing oil or LPG within the published dates. The MCS-certified installer applies for you. Scotland's Home Energy Scotland funding is separate, and Northern Ireland has no dedicated homeowner grant at present.
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.