Air conditioning for extensions and kitchen-diners in Dorchester
Damp South West winters make the dehumidifying side of a heat pump almost as useful as its cooling. In Dorchester, a side wall of a single-storey extension is usually the neatest place for the indoor unit.
An extension in Dorchester with a roof lantern or large glazed doors can overheat quickly on a sunny afternoon. Our Dorset coverage takes in Dorchester, about 24 miles from Bournemouth. Postcode districts we cover here include DT1.
Prices in Dorchester
Air conditioning for extensions and kitchen-diners in Dorchester typically comes in at £1,450–£4,450 per space including VAT, based on South West England rates. That is broadly in line with national guide prices. What moves a quote in Dorchester up or down is mostly pipe length, how high the outdoor unit goes, and whether a new electrical circuit is needed. For reference, the Large single option in Dorchester (one 5–7 kW unit for a large glazed space) usually comes to about £2,050–£2,850.
Single unit
One 3.5–5 kW unit for a medium extension.
Large single
One 5–7 kW unit for a large glazed space.
Twin units
Two indoor units on a multi-split for long or L-shaped spaces.
Guide prices show VAT at 20%. HMRC treats most fixed air conditioners and air-to-air heat pumps installed in homes as energy-saving materials, zero-rated until 31 March 2027 when we supply and fit them. If your installation qualifies, your quote shows 0% VAT and a lower price. Servicing, repairs, cleaning and controls are charged at 20%.
Planning and permissions
Since 29 May 2025, England's permitted development rules allow larger outdoor units (up to 1.5 m³) and no longer require a 1 m gap to the boundary, provided the MCS 020(a) noise check is met. Listed buildings and pitched-roof installs still need permission.
The survey
The free survey is where the real price is set: room measurements, pipe and drain routes, electrical checks and the outdoor unit position, all written into your quote. A survey in Dorchester usually takes one to two hours. We measure the rooms, check the walls and the consumer unit, agree the outdoor unit position with you and photograph the pipe routes.
What is included
Included as standard in Dorchester:
- Placement clear of the hob and oven
- Free survey with glazing and roof heat-gain check
- Pressure test, vacuum and commissioning
- One or two units sized for the whole space
- Handover of the remote or app
Nearby
Nearby, we also cover Weymouth (7 miles), Wareham (14 miles) and Bridport (14 miles). See all services in Dorchester or air conditioning for extensions and kitchen-diners across Dorset.