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 Bedfordshire homes where the clearest unit position is away from the plant cupboard, a split system allows a longer route indoors. Owners across Bedfordshire can compare split and monobloc designs side by side at a survey in Bedfordshire. Properties on exposed sites around Bedfordshire can avoid outdoor water pipes altogether with a split system.
Who it suits
- Owners who would rather not use glycol or anti-freeze valves
- 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
- Houses with indoor wall space for a boiler-sized hydrobox
Grants and rules for heat pumps in England
Homes in Bedfordshire 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.
Installing heat pumps is zero-rated for VAT across the UK until 31 March 2027. Since 29 May 2025, permitted development in England allows up to two air source heat pumps on a house, each up to 1.5 m³, with no blanket 1 m boundary rule — the installation must still meet the MCS planning standards, including the noise check. Listed buildings, flats and some conservation-area positions need extra consent, which we check at survey.
Split system heat pumps prices in Bedfordshire
These are guide prices for Bedfordshire, 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 | After £7,500 grant |
|---|---|---|---|
| 1–2 bedroom flat or small terrace | 4–5 kW | £9,700–£12,750 | £2,200–£5,250 |
| 2–3 bedroom terrace or semi | 5–7 kW | £10,700–£13,750 | £3,200–£6,250 |
| 3 bedroom semi or small detached | 6–9 kW | £12,250–£15,800 | £4,750–£8,300 |
| 4 bedroom detached | 8–12 kW | £14,300–£18,350 | £6,800–£10,850 |
| 5+ bedroom or larger older house | 11–16 kW | £16,850–£22,950 | £9,350–£15,450 |
Installed, inc VAT: unit, cylinder, controls, minor pipework and commissioning.
Towns we cover in Bedfordshire
We cover 9 towns in Bedfordshire for split system heat pumps. Each links to local guide prices and the grant position for England.
| Town | Postcode district | Nearest town | Midwinter daylight |
|---|---|---|---|
| Luton | LU1 | Dunstable | 7 h 46 min |
| Bedford | MK40 | Kempston | 7 h 43 min |
| Dunstable | LU6 | Luton | 7 h 46 min |
| Leighton Buzzard | LU7 | Dunstable | 7 h 45 min |
| Ampthill | MK45 | Flitwick | 7 h 44 min |
| Kempston | MK42 | Bedford | 7 h 43 min |
| Biggleswade | SG18 | Sandy | 7 h 43 min |
| Flitwick | MK45 | Ampthill | 7 h 44 min |
| Sandy | SG19 | Biggleswade | 7 h 43 min |
Split system heat pumps questions
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.
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.
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.