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.
In County Antrim, a hydrobox often goes in an utility room or garage, with the cylinder alongside. Flats and terraces in County Antrim with a small yard or flat roof can suit a compact split outdoor unit. In County Antrim homes where the clearest unit position is away from the plant cupboard, a split system allows a longer route indoors.
Who it suits
- Owners who would rather not use glycol or anti-freeze valves
- Homes where the outdoor unit must sit some distance from the plant space
- Exposed or frost-prone sites where outdoor water pipes would be a risk
- Small yards, roofs or balconies that suit a more compact outdoor unit
Grants and rules for heat pumps in Northern Ireland
Northern Ireland does not have a dedicated heat pump grant for homeowners at present, and the Boiler Upgrade Scheme does not apply here. Heat pumps have sometimes been funded through the Northern Ireland Sustainable Energy Programme, so it is worth checking what is open when you enquire about a home in County Antrim.
There is no VAT on installing a heat pump in Northern Ireland until 31 March 2027, the same as in Great Britain. Planning and building control here follow Northern Ireland's own rules, so the survey checks the unit position against them.
Split system heat pumps prices in County Antrim
The ranges below are typical installed prices for homes in County Antrim, including VAT. A survey sets the exact figure, because two similar-looking houses in County Antrim can need quite different radiators and pipework.
| Home | Typical size | Installed guide price |
|---|---|---|
| 1–2 bedroom flat or small terrace | 4–5 kW | £9,200–£12,150 |
| 2–3 bedroom terrace or semi | 5–7 kW | £10,200–£13,100 |
| 3 bedroom semi or small detached | 6–9 kW | £11,650–£15,050 |
| 4 bedroom detached | 8–12 kW | £13,600–£17,450 |
| 5+ bedroom or larger older house | 11–16 kW | £16,000–£21,850 |
Installed, inc VAT: unit, cylinder, controls, minor pipework and commissioning. No dedicated heat pump grant currently applies in Northern Ireland.
Towns we cover in County Antrim
We cover 11 towns in County Antrim for split system heat pumps. Each links to local guide prices and the grant position for Northern Ireland.
| Town | Postcode district | Nearest town | Midwinter daylight |
|---|---|---|---|
| Belfast | BT1 | Newtownabbey | 7 h 15 min |
| Lisburn | BT27 | Belfast | 7 h 16 min |
| Newtownabbey | BT37 | Belfast | 7 h 14 min |
| Carrickfergus | BT38 | Newtownabbey | 7 h 13 min |
| Ballymena | BT42 | Antrim | 7 h 12 min |
| Antrim | BT41 | Ballyclare | 7 h 13 min |
| Larne | BT40 | Carrickfergus | 7 h 12 min |
| Ballycastle | BT54 | Ballymoney | 7 h 07 min |
| Ballyclare | BT39 | Antrim | 7 h 13 min |
| Ballymoney | BT53 | Coleraine | 7 h 09 min |
| Portrush | BT56 | Portstewart | 7 h 07 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.
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.
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.