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Mini Split Heat Pumps: Ductless Heating and Cooling

Mini split heat pumps provide energy-efficient heating and cooling without ductwork. They are an increasingly popular, cost-effective replacement for inefficient baseboard electric heating and window air conditioners in older homes. These ductless systems are also a good choice for home additions where installing ductwork is expensive or not feasible, and to improve poorly heated or cooled rooms.

How they work

Mini split systems have an outdoor unit comprised of a compressor and condenser, and an indoor air handler. A conduit, which contains a power cable, refrigerant tubing and a condensate drain connect the outdoor unit with the air handlers inside. Refrigerant flows constantly through the tubing. In winter, the refrigerant absorbs heat from the outside air and brings it inside as it evaporates into a gas. Heat is transferred from the refrigerant as it condenses back into a liquid. In summer, this process is reversed as the heat pump provides cooling by moving warm inside air outdoors.

Mini split models have as many as four indoor air-handling units connected to one outdoor unit. The number depends on how much heating and cooling is needed in area of the home. Each air-handling unit comes with its own thermostat, providing individual control for specific rooms or zones.

Benefits of mini-split systems

For many homeowners, mini split heat pumps provide a number of important advantages over central air conditioning systems, as well as window or wall units:

  • Energy savings. Mini splits have no ducts. Ductwork is responsible for up to 30 percent of heating and cooling losses in central air systems, according to the U.S. Department of Energy, especially if the ducts are in an unconditioned space.
  • Reliable heating and cooling. Like other heat pumps, mini split systems can deliver energy-efficient heating and cooling. In colder climates, a backup heating system may be required.
  • Ease of installation. Mini splits are easier to install than other types of space-conditioning systems. Typically, hookup between indoor and outdoor units only requires a small hole in the wall and connecting conduits are available in a variety of lengths.
  • Design flexibility. Indoor air handlers can be suspended from the ceiling, mounted into a drop ceiling or hung on a wall. Floor-standing units are also available, and many models come with remote controls to make turning the system on and off more convenient.

Mini split systems typically cost more to install than other heating and cooling systems, although lower operating costs and financial incentives can help quicken your return on investment. See the Database of State Incentives for Renewables and Efficiency (DSIRE) for incentives available in your area.

When installing a system, look for a contractor with experience handling mini split systems. Also, be sure to purchase a unit that is ENERGY STAR qualified for energy-efficient performance. Used for decades worldwide, mini split heat pumps are a proven technology that some U.S. homeowners may not be familiar with.

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This article previously appeared in the Entergy Solutions Plus newsletter, and is used with permission.

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