Air Conditioning Systems Compared: Part II
In Part I, we looked at two different types of split system, and at window- and wall-mounted systems. Here we’re going to cover a couple of very different systems.
These are called package units because the components are all together in one package. But unlike the wall and window units, a package system can use ductwork. They are often installed on the roof of a building and the vents go straight down from them to the floors below. Some package units, such as in large, open-plan buildings like warehouses, might use no ductwork at all, or just enough to reach a vent in the ceiling below the unit. The less ductwork used, the less cooling is lost, and because cold air falls downward, they are often very efficient for single-story buildings with open interiors. Installation usually requires a crane, but it’s still simpler than most ducted split systems since it requires little or no measurement.
The kind without ducting is not a good choice for your home, as it can’t distribute cool air to multiple rooms evenly. And since the system is so close to whatever space it is cooling, they can be noisier than other systems. One advantage of ductwork is that separating the unit from the rooms lowers the noise. But even with ductwork, servicing your system will still involve a technician getting up onto your roof.
Known slangily as “swamp coolers,” evaporative systems differ from the previous ones by using water. Other common systems use lines and coils with refrigerant in them, with compressors and expansion valves to change the physical state of the refrigerant and transfer heat. Evaporative coolers are low tech and simply blow air through damp material like fabric or cardboard, which cools it down. They do not work well in humid environments and are best suited to dry climates.
Evaporative systems do not need an indoor space to be sealed against outside air, because they draw in fresh outside air and cool it down directly. They are environmentally friendly because most refrigerants we use today – chlorofluorocarbons or hydrofluorocarbons – are either greenhouse gases or bad for the ozone layer. They cost less to operate too since they use a fan but not a compressor.
The drawbacks include its low effectiveness in humid air, which also means it can work better on some days than on others. They need a water supply too, so unless it’s designed to connect to a hose, someone will have to pour water in every so often. There is also more maintenance, as all parts that get wet have to be periodically checked and cleaned for mineral deposits.
How do I know what system I have?
What system you have will determine where it is. In your home, you will know you have a mini-split system if there are units on your walls with their own control panels. A window unit is easy to identify. If there is a large unit in your basement, attic, or a closet, and an outdoor unit in the yard, then it’s a standard split system. Whatever and wherever it is, don’t try to service it yourself unless you’re properly trained. Not knowing what you’re doing can lead to electrocution and other injuries (apart from voiding your warranty), so call a professional if something is wrong.