A monobloc heat pump is an air-to-water unit with the entire refrigerant circuit, including the compressor, heat exchangers and refrigerant, sealed inside the outdoor casing. Heat is passed to water inside the unit, and insulated water pipes carry it into the house to the cylinder and heating system. Nothing containing refrigerant comes indoors, which is a big part of why monobloc units suit so many UK homes.
Bungalows in Wiltshire often let the unit sit right beside the plant cupboard, keeping water pipes short. For Wiltshire terraces with small yards, the survey confirms the unit fits with the clearances it needs. Semi-detached homes in Wiltshire often have a side wall where a monobloc unit can sit on a frame, clear of the path.
Who it suits
- Homes where the unit can sit within a short pipe run of the cylinder
- Houses and bungalows with outdoor space close to where pipes enter the home
- Owners who want the simplest installation, with no indoor refrigerant
- Households that want to keep refrigerant work out of routine servicing
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.
Monobloc heat pumps prices in Wiltshire
Here are typical prices for monobloc heat pumps in Wiltshire, 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 | £9,600–£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 Wiltshire
We cover 12 towns in Wiltshire for monobloc heat pumps. Each links to local guide prices and the grant position for England.
| Town | Postcode district | Nearest town | Midwinter daylight |
|---|---|---|---|
| Swindon | SN1 | Marlborough | 7 h 49 min |
| Salisbury | SP1 | Amesbury | 7 h 54 min |
| Trowbridge | BA14 | Bradford-on-Avon | 7 h 51 min |
| Chippenham | SN15 | Corsham | 7 h 50 min |
| Melksham | SN12 | Corsham | 7 h 51 min |
| Warminster | BA12 | Trowbridge | 7 h 53 min |
| Calne | SN11 | Chippenham | 7 h 50 min |
| Devizes | SN10 | Calne | 7 h 51 min |
| Amesbury | SP4 | Salisbury | 7 h 53 min |
| Bradford-on-Avon | BA15 | Trowbridge | 7 h 51 min |
| Corsham | SN13 | Chippenham | 7 h 50 min |
| Marlborough | SN8 | Swindon | 7 h 50 min |
Monobloc heat pumps questions
What is the difference between monobloc and split heat pumps?
A monobloc unit holds all of its refrigerant in the outdoor unit and sends heated water into the house. A split system has an outdoor unit and an indoor unit called a hydrobox, connected by refrigerant pipes, with heat passed to water indoors. Monobloc installs are simpler; splits avoid outdoor water pipes but need an F-gas certified engineer for the refrigerant work. Our monobloc vs split guide compares them.
How far can a monobloc unit be from the house?
Usually as close as practical, because water pipes outside lose heat and need frost protection. Manufacturers set limits on pipe length and size, and longer runs need larger, better-insulated pipes. Most homes site the unit against or near an outside wall close to where the pipes enter. If the only good position is far from the house, a split system may suit better.
Do monobloc heat pumps need an F-gas engineer?
For a typical installation no refrigerant work is needed on site, because the refrigerant circuit is sealed in the outdoor unit at the factory. That is one reason monobloc installs are simpler. If the sealed circuit ever develops a fault or leak, any repair to it must be done by an F-gas certified engineer, as with every refrigerant system.
What refrigerant do monobloc heat pumps use?
Most use R32 or R290. R290 is propane, a natural refrigerant with a very low global warming impact, and some models use it to reach higher flow temperatures. Because R290 is flammable, manufacturers set clearance zones around the unit from openings such as windows, doors and drains, which the survey takes into account when choosing a position.