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Selecting the right type of Air conditioning installation
Types of air conditioner
- Split-system: These have two parts: an outdoor compressor unit and an indoor unit connected by pipes. They’re usually used to cool one or more rooms, or an open-plan area,
of up to 60 square meters. Price range: £600-£5000
- Multi-split: A type of split-system, with one outdoor unit connected to two or more indoor units. This can be a good way to cool or heat two or three rooms that are
reasonably close together, when separate split-systems or a ducted system aren’t possible due to space limitations.
- Ducted: The best option for temperature control throughout a large home, this consists of a central unit connected by ducts to air outlets and sensors in each room, with a
control panel to set the target temperatures and the zones of the house to cool or heat. See our separate ducted air conditioner buying guide for more details. Price
- Wall/window: These models are usually installed in a window or external wall, and can cool rooms and open-plan areas of up to 50 square metres. Smaller units can be plugged
into a normal power point; larger ones may require additional wiring. We don’t currently include these models in our reviews, because there are fewer on the market now, as split-systems are more
efficient and have become more affordable in recent years. Price range: £400–£1100.
Types of indoor unit
- High wall: the most common form of split-system, with the indoor unit mounted high on a wall. This allows the air flow to easily blow across the room, and the cool air
will sink down and push the hot air up and away.
- Floor-mounted: the indoor unit is wall-mounted but at floor level — this might better suit some rooms, and could be a better option if you mainly use the unit for
heating, as the hot air will come out at your level and rise to the ceiling.
- Cassette: these have the indoor unit mounted in the ceiling. Some models can be mounted in either the ceiling or the floor.
Choosing the right capacity
Cooling and heating capacities (sizes) are rated in kilowatts (kW). A small room might require a 2.5kW model, while a large open-plan area might need 6kW or more. It’s important to accurately
calculate the required cooling or heating capacity of your new air conditioner.
Some installers and online calculators offer only a simplistic analysis and may tend to recommend a larger capacity than you really need. A proper calculation takes all the room’s details into
- The size of the room: length, width and height.
- The type of room: living room, open-plan living room and kitchen, bedroom, etc.
- The size and orientation of the windows and glass doors. A large south window can let in a lot of heat in summer.
- Shading and curtains on the windows.
- Insulation of the floor, ceiling, and walls.
- The local climate.
Delta T Cooling is currently looking into options for building a capacity calculator to help you determine the right size of air conditioner for your needs. Meanwhile, try the size calculator on
Choose a model with equal or slightly greater capacity for the room. For example, if you calculate the room needs a 6kW model, then look for an air conditioner with
rated cooling capacity in the range 6kW to 6.5kW (roughly). It’s probably a safer bet to get a model slightly above the required capacity than slightly below it; a little extra grunt may help in
extreme temperatures. But don’t go too much above the required capacity.
- Models too powerful for the room size may run frequent short cycles to achieve the target temperature – which is like tapping the accelerator in your car to maintain
speed instead of applying steady pressure. This can result in the room getting too cold or hot; inadequate dehumidification (i.e. not drying the air enough. making the room feel less comfortable);
increased power usage and running costs; and wear and tear on the system.
- Underpowered models may have to run more often at maximum output, dry the air too much and you’ll similarly suffer excessive wear.
Heating and cooling appliances account for about 40% of the energy usage of the average home. To save money when running your air conditioner, there are several things you can do.
- Size: Having the correct size of air conditioner is an important first step (see Choosing the right capacity).
- Star ratings: a model with more stars will be more efficient and use less power than a model with fewer stars.
- Delta T Cooling air conditioner reviews rate each model for cooling and heating efficiency more precisely than the star ratings, and give an indicative running cost for each model.
- Make your home as energy-efficient as possible; see our top 10 tips on keeping your home cool efficiently and effectively.
- Use Economy mode (“Eco mode”) if your air conditioner has one.
- Set the thermostat (target temperature) to a reasonable temperature so the system doesn’t have to work too hard and use more power than really necessary.