A split system heat pump is an air-to-water heat pump in two parts: an outdoor unit that collects heat from the air, and an indoor unit called a hydrobox where that heat is passed into the water for your heating and hot water. The two are connected by insulated refrigerant pipes rather than water pipes, so there is no water outside to freeze.
In Devon, a hydrobox often goes in an utility room or garage, with the cylinder alongside. In Devon homes where the clearest unit position is away from the plant cupboard, a split system allows a longer route indoors. Installers covering Devon keep refrigerant routes neat and protected along the outside wall.
Who it suits
- Houses with indoor wall space for a boiler-sized hydrobox
- Exposed or frost-prone sites where outdoor water pipes would be a risk
- Homes where the outdoor unit must sit some distance from the plant space
- Small yards, roofs or balconies that suit a more compact outdoor unit
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 Devon
The ranges below are typical installed prices for homes in Devon, including VAT. A survey sets the exact figure, because two similar-looking houses in Devon 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 Devon
We cover 18 towns in Devon for split system heat pumps. Each links to local guide prices and the grant position for England.
| Town | Postcode district | Nearest town | Midwinter daylight |
|---|---|---|---|
| Plymouth | PL1 | Saltash | 8 h 01 min |
| Exeter | EX4 | Crediton | 7 h 57 min |
| Paignton | TQ3 | Torquay | 8 h 00 min |
| Torquay | TQ1 | Paignton | 8 h 00 min |
| Newton Abbot | TQ12 | Torquay | 7 h 59 min |
| Exmouth | EX8 | Sidmouth | 7 h 58 min |
| Barnstaple | EX31 | Bideford | 7 h 54 min |
| Bideford | EX39 | Barnstaple | 7 h 54 min |
| Tiverton | EX16 | Crediton | 7 h 56 min |
| Crediton | EX17 | Exeter | 7 h 57 min |
| Dartmouth | TQ6 | Paignton | 8 h 01 min |
| Honiton | EX14 | Sidmouth | 7 h 57 min |
| Ilfracombe | EX34 | Barnstaple | 7 h 52 min |
| Kingsbridge | TQ7 | Dartmouth | 8 h 02 min |
| Okehampton | EX20 | Tavistock | 7 h 57 min |
| Sidmouth | EX10 | Honiton | 7 h 58 min |
| Tavistock | PL19 | Plymouth | 7 h 59 min |
| Totnes | TQ9 | Paignton | 8 h 00 min |
Split system heat pumps questions
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.
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.
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.
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.