Ductless split-system air-conditioners are relatively new to North America, although the Japanese manufactured and used them in their country for many years. They are ideal for older homes where ductwork is not feasible or desirable.
Ductless split-system air-conditioners combine the zoning flexibility of a conventional room unit with the whole-house cooling potential of central systems. They have two main components: a compressor/condenser, as well as an air handling unit, which contains an evaporator and a fan.
The compressor and condenser are housed as one unit and located outdoors. The evaporator unit is indoors, in the area to be cooled. A conduit, which houses the power cable, refrigerant tubing, suction tubing, and condensate drain, links the outdoor and indoor units.
The advantages of ductless split-systems over room and central air-conditioners are: easy installation, quiet operation, versatility in zoning and design, and security. The split systems also eliminate the loss of cool air as it passes through the ductwork.
A key advantage of split systems is their ease of installation. Hook-up requires only a three-inch hole (7.62 centimeters) in the wall for the conduit. Unlike with central air conditioning, you do not need ductwork. Since the compressor in most ductless split-systems is as much as 50 feet (15.24 meters) away from the indoor evaporator, it is usually possible to cool rooms on the front side of the house, while still hiding the compressor in a less conspicuous area. The compressor units also fit well on flat commercial building rooftops.
By providing zone cooling, ductless split-system air-conditioners save energy, since only the rooms that are occupied need to be cooled. A thermostat independently controls each zone. Therefore, operating costs are often lower than those of central systems that cool every room, whether it is in use or not.
If you cannot afford to purchase an air conditioner for the whole house, you can also buy the system one zone at a time. A single outdoor unit controls from one to four zones, depending on the size of the unit. Commercial buildings tend to use larger units. Typically, the Btu per hour rating (Btu/h) of these units ranges from 8,700 to 60,000, and the Seasonal Energy Efficiency Ratio (SEER) ratings are between 10.0 and 11.5.
When compared to other add-on systems, split-systems also provide better interior design options. The air handlers can be suspended from a ceiling, mounted flush into a drop ceiling, or hung on a wall. Floor-standing models are also widely available. Most indoor units are low-profile models, no more than seven inches deep, and come with decorative jackets. Most newer models come with a remote control unit as standard equipment. This allows the positioning of air-handling units high on a wall or suspended from a ceiling, without compromising convenience.
Unsecured room air-conditioners provide an easy entrance for intruders. Split- systems are more secure than window units since there is only a small hole in the wall.
The primary disadvantage of split-system units is their cost. Split-system air-conditioners cost about $1,500-$2,000 per ton (12,000 Btu/h) of cooling capacity. This is about 30% more than central systems, and may cost twice as much as window units of similar capacity.
The installer must judge the best location for the air handling unit. The air handler blows air up to 30 or 40 feet. If the system is improperly positioned and/or sized, the air can bounce off a wall or another obstruction. This results in short-cycling, which wastes energy and does not provide the desired temperature control. An oversized unit also costs more than a correctly sized unit.
Some people may also not like the appearance of the air handling unit. While less obtrusive than a window unit, they seldom have the built-in look of a central system. There must also be drainage for condensate outside the building. If the drainage is not well placed, the condensate can stain concrete or building materials.
Qualified service centers may not be easy to find until the systems become more widespread. Total Comfort offers ductless split-system installation and repairs.