What Is A Ductless Heat Pump?

What is a ductless heat pump? A ductless heat pump delivers the air from the indoor part of the heat pump to the space that has been cooled without the means of a duct system. Ductless heat pumps can be...

Ductless heat pumps can be an energy efficient system for any home. How do they work? Our heat pump expert, Pete Peterson, owner of Geothermal Supply Company, with more than 35 years experience in the heat pump industry, gives us an explanation.


"Most heat pumps installed will have a duct system or an air distribution system; the ductless does not. It's just one that would hang on the wall and deliver the air from the indoor part of the heat pump, straight to the space that has been cooled without the means of a duct system," Peterson says.

Installing central air conditioning in a home that does not have forced air ducts can be difficult. Ductless mini-split heat pumps provide a unique solution to bringing central air conditioning into homes. By piping refrigerant to individual coils within air handlers mounted throughout a home (rather than a single refrigerant coil/air handler and central ductwork), mini-split heat pumps do not require ductwork for central air conditioning. Because the refrigerant lines take up much less room than do typical ducts, much less effort is required in installation in a retrofit.

Ductless mini-split systems combine the flexibility of room air conditioners with the whole house cooling of central systems. Although some systems provide heating and cooling, ductless mini-split heat pumps are usually installed primarily for cooling.

Peterson says in a conventional heat pump, a single indoor unit (refrigerant coil and air handler) and single outdoor unit (condenser and compressor) serve the entire house. Air is cooled at the evaporator coil and distributed around the house via ductwork. In ductless systems, there is (usually only) one outdoor unit serving multiple indoor units (each containing a refrigerant coil and blower). Refrigerant is piped from the outdoor unit through small-diameter insulated refrigerant lines directly to individual rooms or zones. Cooled air is blown into the room by a fan in the individual evaporator units. The term "mini" is used to describe the small indoor units located in each room or zone.




While distribution energy losses in conventional systems have been estimated as high as 30 percent, distribution losses for ductless systems are about one to five percent.

Ductless heat pumps are installed using conventional methods for heat pump/air conditioner installation. However, extra care must be taken to prevent refrigeration leaks and to ensure proper operating pressures. It takes two installers about a day to install a system having up to three zones. Wiring for power and controls is easier than with a conventional unit since wires can be run along with the refrigerant lines. Refrigerant lines from outdoor units can span up to one hundred feet to indoor units.

The cost of ductless heat pumps has declined as the technology has become established in the marketplace. A 2004 polling of ductless heat pump suppliers showed costs for ductless heat pumps to run between $500 and $900 per ton, depending upon the type of system and the number of zones desired per unit.

Ductless systems can reduce energy costs for heating and cooling over conventional heat pumps. Cost will vary with equipment efficiency rating and the leakiness (and location) of ducts to which it is compared.

Indoor units are about six to eight inches deep and are mounted flush on a wall or ceiling, or recessed in a drop ceiling. A three-inch hole behind the unit is used for attaching wiring, refrigerant lines, control cables, and a condensate drain.

If a ductless heat pump looks like the best option for you, make sure you choose an installation company with excellent references. Once all your research is done, you can have the peace of mind that you did everything in your power to make the best choice for you and your family.

© High Speed Ventures 2011