The trade-off is that the pipes between the outdoor unit and the house carry water, so they must be protected from freezing. That is done with glycol (an anti-freeze) in the system or with anti-freeze valves that release water from the outdoor pipework if it nears freezing, for example during a power cut in cold weather. Keeping the outdoor pipe run short and well insulated also helps efficiency.
A survey in Dorset checks the unit position, pipe route and clearance zones together for homes across Dorset. Semi-detached homes in Dorset often have a side wall where a monobloc unit can sit on a frame, clear of the path. In exposed spots around Dorset, frost protection for the outdoor pipework is chosen with the site in mind.
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
- Households that want to keep refrigerant work out of routine servicing
- Owners who want the simplest installation, with no indoor refrigerant
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.
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.
Monobloc heat pumps prices in Dorset
These are guide prices for Dorset, 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 | £9,600–£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 Dorset
We cover 12 towns in Dorset for monobloc heat pumps. Each links to local guide prices and the grant position for England.
| Town | Postcode district | Nearest town | Midwinter daylight |
|---|---|---|---|
| Bournemouth | BH2 | Christchurch | 7 h 57 min |
| Poole | BH15 | Bournemouth | 7 h 57 min |
| Weymouth | DT4 | Dorchester | 7 h 58 min |
| Christchurch | BH6 | Bournemouth | 7 h 57 min |
| Ferndown | BH22 | Wimborne Minster | 7 h 56 min |
| Dorchester | DT1 | Weymouth | 7 h 57 min |
| Wimborne Minster | BH18 | Ferndown | 7 h 57 min |
| Blandford Forum | DT11 | Wimborne Minster | 7 h 56 min |
| Bridport | DT6 | Dorchester | 7 h 57 min |
| Sherborne | DT9 | Yeovil | 7 h 55 min |
| Swanage | BH19 | Poole | 7 h 58 min |
| Wareham | BH20 | Poole | 7 h 58 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.
Is glycol or anti-freeze valves the better option?
Neither is right for every home. Glycol gives reliable frost protection without draining but slightly reduces efficiency and needs its concentration checked at servicing. Anti-freeze valves keep the system water plain but release water if pipes near freezing during a power cut, so the system then needs refilling. The installer recommends one based on the unit, pipe run and how exposed the site is.
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.