AC without Ducts

If you live in a old house without duct work, then you know the limited options you have with regards to putting in an Air Conditioning System. Ductless split-system air-conditioners are relatively new to North America, although the Japanese manufactured and used them in their country for many years.

Ductless split-system air-conditioners combine the zoning flexibility of a conventional room unit (a single air-conditioner installed through a wall or a window frame) with the whole-house cooling potential of central systems. Like central systems, they have two main components: a compressor/condenser, as well as an air handling unit, which contains an evaporator and a fan. Some units operate as heat pumps and provide both summer cooling and winter heating.

The noisy compressor and condenser are housed as one unit and located outdoors. The quiet fan/evaporator unit is indoors, located 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.

Advantages:

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

Ductless split-system air-conditioners operate relatively quietly, since the compressor is outside and the evaporator unit's fan generally runs at a low speed. Variable speed high efficiency fans are also available.

When it comes to efficiency you have two advantages. Areas of the house that are not in use can be turned down to save money. Also, the system does not loose its cool air through the duct. Ducts moving through a uncontrolled area, such as an attic, can loose up to 30% of its cooling capacity. 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.

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 (17.78 centimeters) 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.

Disadvantages:

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. It also needs to be the correct size for the area it cools. 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.