An alternative to window air conditioners
By James Dulley from September 2013 Issue
Credit: Penny Kephart
We added a room, but our central air conditioner doesn't cool it well. Our second-floor master bedroom also does not stay cool. Does it make more sense to install a window air conditioner or a mini-split system? -Kyle F.
Whether you install a mini-split heat pump or a window air conditioner depends on what you need and want from the unit. Most people install a window air conditioner to provide extra cooling in a room at a low initial cost. Energy efficiency is not the primary concern. Mini-split heat pumps offer many bonus features (quieter operation, variable compressor speeds, heating in winter) and increased efficiency, but at a higher initial cost.
A window air conditioner has all its components inside the single cabinet mounted in the window. Though it is insulated against heat flow, it still is not ideal for energy efficiency.
A mini-split system is similar to a central air conditioner or heat pump. But instead of using an air-duct system, a mini-split requires few changes to your existing walls. The coil is mounted in a fan unit on the wall or ceiling of the room, then connected to the outdoor unit by refrigerant and electric lines. Only a 3-inch-diameter hole needs to be cut through the wall, and the condensate drain from the evaporator coils can go out through the same hole.
Just as in a conventional whole house system, in a mini-split system the condenser fan, coils, and compressor are in an outdoor unit. However, for the mini-split the outdoor part is flat and small, and for some models may be placed up to 100 feet from the room or group of rooms to be cooled or heated.
The main drawback for mini-split heat pumps is cost. A window unit generally sells for less than $300; mini-splits can run to more than $1,000, plus the cost of installation. Also, unlike a window unit, mini-splits can't be moved once installed.
Installing either option should help you with zone cooling of your house, which can lower your monthly electric bill. Setting your whole-house system's thermostat higher at night, then relying on the window unit or mini-split to keep only your sleeping area cooler, may provide substantial overall electricity savings.
Weighing the mini-split AC pros and cons
Mini-split systems offer advantages and disadvantages over adding window air-conditioning units. They cost more, but they can be quieter, more efficient, and provide heating as well as cooling. Get more details to help you decide on the Web site of the U.S. Department of Energy at www.energy.gov, then in the search box type "ductless mini-split heat pumps."
Mail requests and questions to JAMES DULLEY, Kentucky Living, 6906 Royalgreen Drive, Cincinnati, OH 45244, or visit www.dulley.com.