The most common question we get from homeowners considering air conditioning is: why do the prices I see online vary so much? A wall-mounted unit might show as £300 on a manufacturer's website, then a quote comes back at £2,000. Understanding what's in that difference stops you comparing jobs that aren't comparable.
This guide breaks down real installed costs for Hertfordshire homes — not just unit prices.
Installed Costs at a Glance
These are complete installed prices — equipment, labour, refrigerant pipework, electrical connection and commissioning:
| System Type | Typical Installed Cost | |---|---| | Single split system (1 room, standard) | £1,200 – £2,000 | | Single split system (larger room or premium unit) | £2,000 – £3,500 | | Multi-split — 3 indoor units | £3,500 – £6,000 | | Multi-split — 5 indoor units | £5,500 – £9,000 | | Cassette unit (open-plan or commercial space) | £2,000 – £4,500 per unit |
The wide ranges exist because two installations that look identical on paper can be very different jobs. Here's what drives the difference.
What Changes the Price
Pipe run length and complexity. The refrigerant pipework connecting the outdoor unit to the indoor unit needs to be routed through the building. A back-to-back installation where the outdoor unit sits directly behind the indoor unit is the simplest and cheapest scenario. Running pipework across three floors of a Victorian terrace is a different job entirely.
Indoor unit style. Wall-mounted units are the most common and most affordable to install. Ceiling cassette units cost more because they require ceiling access and structural fixing, but give four-way airflow that works far better in open-plan spaces. Ducted systems — where everything is concealed above ceiling level — cost the most but leave no visible hardware at all, which suits renovation projects.
Electrical supply. Most installations need a dedicated circuit from the consumer unit. If yours is nearby, this is straightforward. If the consumer unit is on the opposite side of a three-storey house, or if it's already full and needs a board upgrade, the electrical element adds cost.
Outdoor unit position. Wall bracket mounting at ground floor level is standard. High-level mounting, restricted-access rear gardens, or rooftop locations where scaffolding or specialist equipment is needed will add to the price.
Brand and specification. We install Daikin, Mitsubishi Electric, Samsung, LG and Panasonic — all reliable brands with strong service networks in the UK. The differences come down to noise levels (quieter units cost more), energy efficiency ratings, filter specifications and smart home integration. We don't install units we wouldn't put in our own homes, which rules out the cheapest budget options.
Air Conditioning for Heating — Not Just Cooling
This surprises many people: all modern inverter air conditioning units are reverse-cycle heat pumps. They extract heat from the outdoor air and move it inside, even in cold weather. In heat mode, they can provide supplementary or primary heating for a room or home office.
For a room that's hard to heat efficiently — a converted loft, a home office above a garage, a ground floor extension — running an air conditioning unit in heat mode is often cheaper per hour than an electric panel heater or storage radiator. It's worth factoring into the cost calculation.
How Long Installation Takes
- Single split system: One day
- Multi-split, 2–4 units: 1–2 days
- Larger multi-split or commercial cassette systems: 2–3 days
We plan pipework routes before we start, minimise visible runs where possible, and clear up fully on completion.
Annual Servicing Costs
Factor this in: air conditioning needs annual servicing. For systems containing more than 3kg of refrigerant, annual F-Gas leak checks are a legal requirement, which we include in service visits.
An annual service runs £90–£180 per system depending on the number of units. Without it, efficiency drops, filters block, the system lifespan shortens, and most manufacturers' warranties require evidence of regular servicing.
How to Get an Accurate Quote
Every installation is different enough that we don't quote over the phone. We carry out free site surveys across Hertfordshire — assessing indoor unit position, pipe routes, electrical supply and outdoor unit location — and give you a fixed price that covers everything.
We cover Watford, St Albans, Hemel Hempstead, Rickmansworth, Stevenage, Barnet, Edgware and surrounding areas.
Call 0208 092 1359 or contact us online to arrange a free site visit.