Ductless Central Air Conditioning

Many older homes were built with no provision for central air conditioning. Residential central air conditioners were uncommon prior to the 1960's, and even as late as 1980, were installed in only about one-fourth of U.S. homes. In homes with no central air conditioning, duct systems were rare, as there were other ways to deliver space heating.

Until recently, the only options for air conditioning in homes with no ducts were either to use room units (window or wall air conditioners) or to install a duct system, which can be costly and impractical unless the home is being extensivelyremodeled.

A New Alternative

Now there is another option for homes with no existing ductwork - a ductless split-system central air conditioner or "mini-split". Instead of using a single central air handler with ducts running to each room, this system has multiple fan-coil units connected via refrigerant piping to a single outdoor unit.

This system combines the zoning flexibility of room units (the ability to cool individual rooms independently) with the whole-house cooling capability of a central system.

The indoor fan-coil unit is smaller than a standard window air conditioner, and much quieter, as the compressor is located in the outdoor unit. The fan-coil unit can be mounted on a wall or suspended from a ceiling. Many come with a remote control, allowing the unit to be mounted high on the wall or on the ceiling.

In addition to providing a new alternative for homes with no ductwork, this system can also be useful for additions where extending the existing duct system is impractical.

Efficiency and Cost

Ductless central air conditioners are available with SEER ratings as high as 18 or 19 - comparable to the highest-efficiency ducted central air systems, but without the duct losses that can reduce overall performance significantly. Some also incorporate variable speed high-efficiency fans. Heat pump versions that provide both air conditioning and space heating are also available.

Currently, the initial cost is typically about twice that of traditional window units and about 30% higher than a standard central system. However, once the cost of adding new ductwork is factored into the equation, the ductless system may be a very cost-effective alternative.

No More Duct Losses

Studies by the U.S. Department of Energy have found that as much as 25-30% of an average home's cooling is lost to unconditioned spaces like attics, due to inefficient duct systems. While it is possible to minimize these losses with insulation and proper duct design and sealing, it can be difficult and time-consuming. Although ductless systems are currently more expensive than traditional ducted systems, the additional cost can be at least partially offset by the savings from eliminating the ducts. When you factor in the energy and operating cost savings from eliminating duct losses, the total cost (initial cost plus annual energy cost) can compare favorably with ducted systems. Over time, as sales of these systems increase and costs come down, they may become a popular option for new homes.

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