Although portable air conditioning units are extremely popular in the UK, as a simple way to add proper cooling to a room, there’s a growing number of full AC installs, known as split or wall-mounted systems. What’s the difference between the two, and which one is best for you? We explain all.
Before we get into the differences between the two systems, it’s important to understand that all air conditioning systems work in the same way, with a cold side and a hot side. Our guide, how do portable air conditioners work?, explains more, but we’ll go over the basics here.
In essence, an AC system takes hot air from inside and pumps it outside: it moves heat around. Each AC unit works in a cycle: refrigerant liquid is pumped through a metal evaporator coil. Internal air is blown over this coil, which causes the refrigerant to absorb heat and moisture from the air, and cold air is blown into the room.
This process causes the refrigerant to turn into a gas, passing through a compressor to increase its heat and thermal efficiency. The hot gas then passes through a condenser, and air is blown over it. The air absorbs the heat from the refrigerant, taking heat out of the system and turning the gas into a liquid.
Refrigerant then passes through an expansion valve, which reduces pressure and lowers its temperature, so the cycle can start again. The difference between the two types of system is where the components are located.
Portable air conditioning
A portable AC system contains everything in a single box that plugs into a standard power socket. With single-hose systems, the air that passes over the condenser is taken from inside the room, with the resulting hot air expelled outside via a duct.
Pumping some internal air outside means that hot air from outside can be pulled into your home to replace the missing air, which adds heat and makes the system less efficient.
A dual-hose system uses a secondary hose to pull in air from outside, which is passed over the condenser coil and then extracted through the second hose. This is a more efficient air exchange, but there’s still some inefficiency in design, and the ducting can leak heat back into the room. And, the air conditioning unit itself generates heat, not all of which is pumped out through the duct.
Secondly, as hoses have to go out of a window, there’s no longer a good seal, even if you use a duct kit, so some hot air from outside makes it inside.
Portable AC units are cheaper to buy and, technically, can be moved from room to room, although they’re typically cumbersome. They’re easy to set up, and a good choice if a split system can be installed in your home. However, they’re more expensive to run, take up a lot of space in a room.
Split air conditioning
With split air conditioning units, the system, as the name suggests, is split between an indoor and an outdoor unit. The indoor unit contains the evaporator coil and a fan, so cold air is blown into the room; however, the condenser and compressor are housed in an outdoor unit.
Indoor units in homes are usually wall-mounted; in offices, where suspended ceilings are common, you tend to find ceiling-mounted units.
With split systems, there’s no ducting; pipework for the refrigerant connects the internal and external systems. This makes heat transfer more efficient, and there’s no exchange of internal and external air. Plus, you can close all of your windows and doors, improving efficiency and allowing you to run the system even when you’re out; with portable units, leaving a window open is a big security risk.
An external unit can be used for multiple internal units, improving efficiency for homes that want AC in more than one room. As such, it’s possible to buy split systems with higher cooling outputs than portable units, designed to deal with higher cooling loads in multiple rooms.
Internally, split AC units are quieter than portable ones, as they only contain a fan. The external unit makes noise, so it’s essential to position it correctly so that it’s not annoying for you or your neighbours.
With the indoor unit on the wall, there’s no floor space taken up, which makes it easier to position furniture.
Split systems are more expensive to install, and the external unit needs a lot of space. Depending on where you want the internal unit and the layout of your home, it may be impractical to have a split system installed. We recently tried to get a split AC system installed on a Victorian terraced house, but the side-return extension downstairs didn’t leave room to easily place the external unit so that we couldn’t do it.
Which is better, portable or split AC?
If you can afford it and need regular cooling, then a split AC system is better: more powerful, more efficient and easier to use. If you can’t have a split system installed because of space requirements, are on a tighter budget, and only need AC occasionally (such as just for a heat wave when one room gets too hot), then a portable AC can still be a good choice.
