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 the West Midlands homes where the clearest unit position is away from the plant cupboard, a split system allows a longer route indoors. Installers covering the West Midlands keep refrigerant routes neat and protected along the outside wall. In the West Midlands, a hydrobox often goes in an utility room or garage, with the cylinder alongside.
Who it suits
- Houses with indoor wall space for a boiler-sized hydrobox
- Small yards, roofs or balconies that suit a more compact outdoor unit
- Exposed or frost-prone sites where outdoor water pipes would be a risk
- Owners who would rather not use glycol or anti-freeze valves
Grants and rules for heat pumps in England
Homes in the West Midlands can use the Boiler Upgrade Scheme, which takes £7,500 off the cost of an air source heat pump when it replaces fossil-fuel or electric heating. Replacing oil or LPG heating qualifies for £9,000 for installations from 21 July 2026 to 31 March 2027, and air-to-air systems for £2,500. The MCS-certified installer named in your quote applies for the grant and deducts it from the price.
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 the West Midlands
Here are typical prices for split system heat pumps in the West Midlands, installed and including VAT. Use the guide price tool for a figure based on your home, then a survey confirms it in writing.
| Home | Typical size | Installed guide price | After £7,500 grant |
|---|---|---|---|
| 1–2 bedroom flat or small terrace | 4–5 kW | £9,500–£12,500 | £2,000–£5,000 |
| 2–3 bedroom terrace or semi | 5–7 kW | £10,500–£13,500 | £3,000–£6,000 |
| 3 bedroom semi or small detached | 6–9 kW | £12,000–£15,500 | £4,500–£8,000 |
| 4 bedroom detached | 8–12 kW | £14,000–£18,000 | £6,500–£10,500 |
| 5+ bedroom or larger older house | 11–16 kW | £16,500–£22,500 | £9,000–£15,000 |
Installed, inc VAT: unit, cylinder, controls, minor pipework and commissioning.
Towns we cover in the West Midlands
We cover 28 towns in the West Midlands for split system heat pumps. Each links to local guide prices and the grant position for England.
| Town | Postcode district | Nearest town | Midwinter daylight |
|---|---|---|---|
| Birmingham | B3 | Edgbaston | 7 h 39 min |
| Coventry | CV1 | Kenilworth | 7 h 40 min |
| Wolverhampton | WV1 | Willenhall | 7 h 38 min |
| Dudley | DY2 | Brierley Hill | 7 h 39 min |
| Walsall | WS1 | Wednesbury | 7 h 38 min |
| Solihull | B91 | Shirley | 7 h 40 min |
| Sutton Coldfield | B75 | Erdington | 7 h 38 min |
| West Bromwich | B70 | Oldbury | 7 h 39 min |
| Halesowen | B63 | Brierley Hill | 7 h 40 min |
| Stourbridge | DY8 | Brierley Hill | 7 h 40 min |
| Smethwick | B66 | West Bromwich | 7 h 39 min |
| Willenhall | WV13 | Bilston | 7 h 38 min |
| Tipton | DY4 | Dudley | 7 h 39 min |
| Shirley | B90 | Hall Green | 7 h 40 min |
| Brierley Hill | DY5 | Stourbridge | 7 h 39 min |
| Aldridge | WS9 | Walsall | 7 h 38 min |
| Wednesbury | WS10 | Bilston | 7 h 39 min |
| Kingswinford | DY6 | Brierley Hill | 7 h 39 min |
| Bilston | WV14 | Willenhall | 7 h 38 min |
| Edgbaston | B15 | Harborne | 7 h 40 min |
| Erdington | B23 | Sutton Coldfield | 7 h 39 min |
| Great Barr | B43 | Walsall | 7 h 38 min |
| Hall Green | B28 | Shirley | 7 h 40 min |
| Harborne | B17 | Edgbaston | 7 h 40 min |
| Kings Heath | B14 | Moseley | 7 h 40 min |
| Knowle | B93 | Solihull | 7 h 40 min |
| Moseley | B13 | Kings Heath | 7 h 40 min |
| Oldbury | B69 | West Bromwich | 7 h 39 min |
Split system heat pumps questions
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.
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 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.