Guides · 3 Min read · updated September 2026

Single room vs multi-room AC — which is right?

One room too hot, or the whole place? The right system depends on how many rooms you need to cool, your property, and what you might want to add later. Read this before getting a quote.

In this guide

→ The key difference
→ When to choose single room
→ When to choose multi-room
→ The cost of expanding later

The key difference

Both systems use the same technology — a wall-mounted indoor unit connected to an outdoor condenser by refrigerant pipework. The difference is how many indoor units share one outdoor condenser.

Single room system

One indoor unit, one outdoor unit. The simplest and most affordable option. Ideal for a bedroom, living room, or home office where one room is the main problem. Installed in 4–6 hours. From £1,800.

Multi-room system

Multiple indoor units sharing one outdoor condenser. More efficient than installing separate single systems and neater from a planning and aesthetic perspective. Installed in one full day. From £3,200.

Full Comparison

	Single Room	Multiple Room
Rooms Cooled	1	2–4
Outdoor Units	1	1
Installation Time	4–6 hours	1 full day
Independent Room Control	N/A	Yes
Cost to Add a Second Room Later	Full New System	Additional indoor unit only
Typical Cost	£1,800–£2,600	£3,200–£5,500

When to choose single room

A single room system is the right choice when one room is significantly hotter than the rest of your home, or when budget is the primary consideration.

Your bedroom is unbearable at night

The most common reason people install AC in the UK. One bedroom unit solves the problem at the lowest possible cost and disruption. → Single room system.

You work from home and need one cool room

A home office unit keeps you productive during heatwaves without cooling rooms you’re not using. → Single room system.

You’re renting or unsure long-term

Lower upfront cost and less disruption makes a single room install a sensible choice if your situation might change. → Single room system.

When to choose multi-room

Multi-room is the better choice when more than one room needs cooling — and it’s often better value than installing two separate single room systems.

You want to cool two or more rooms

One multi-room system with two indoor units typically costs less than two separate single room systems — and gives you only one outdoor unit on the exterior wall. → Multi-room system.

You live in a flat with planning constraints

If you’ve gone to the effort of getting planning permission for an outdoor unit, a multi-room system maximises what you can do with that one unit. → Multi-room system.

You want to cool the bedroom and living room

The most common multi-room scenario. Both rooms independently controlled from one outdoor condenser. → Multi-room system.

The cost of expanding later

One thing worth factoring in: if you install a single room system now but want to add a second room in a year or two, you’ll face two options. With a single room system already installed, adding a second room means a completely new system — a second outdoor unit, second indoor unit, and a full installation. You’ll have two outdoor units on your exterior wall.

With a multi-room system already installed, adding a second indoor unit to an existing outdoor condenser is significantly cheaper — the outdoor unit is already there, you just add another indoor unit and connect it.

If there’s any chance you’ll want a second room in the next few years, it’s often worth
investing in a multi-room system now. Still not sure? Get an estimate at Temlohome.com — your installer will recommend the right system during the site visit.