Ductless Heat Pumps

Though popular for nearly 20 years in Europe and Asia, ductless heat pumps are a relatively new technology in the U.S.  A ductless heat pump will provide efficient heating and cooling and is a smart retrofit add-on to houses with “non-ducted” heating systems, particularly those with electric resistance, space heating (wood, kerosene, or propane), radiators, or oil heat.  They are also great for new additions or adding heat to existing spaces, where extending or installing ductwork may not be feasible.

What is a Ductless Mini-Split Heat Pump? 

As the name implies, ductless heat pumps do not require ductwork to distribute air, eliminating the energy loss from leaky ducts and improving air quality. A ductless heat pump system consists of two main components: the outdoor compressor/condenser, and the indoor air handling unit.  The term “mini-split” is often used because it is possible to connect up to four indoor air handling units to each outdoor compressor/condenser.

How Does It Work?

The interior and exterior units are connected by thin refrigerant lines running through a 3 inch hole in the wall.  The outdoor unit then distributes the refrigerant through this copper tubing to and from the indoor air handler, where the air is conditioned and dispersed throughout the space.  During cooler months, the system works like a standard heat pump, collecting heat from the outdoor air to warm the interior space.  In warmer weather this cycle is reversed, providing cooling to the same space.


When considering a ductless mini-split system, proper design and installation is critical.  Because they operate zonally, correct placement is necessary to ensure comfort and maximize efficiency.  If a unit is oversized or incorrectly located, this can result in short-cycling (rapid starting and stopping), which will waste energy, reduce comfort, and decrease equipment lifespan.  As these systems are relatively new in the US, it can be difficult to find an experienced contractor.  As a specialist in ductless mini-splits, Good Energy Retrofit will walk you through every aspect of installation.  We help you select the correct system for your needs, determine the most efficient placement, and install the units in a safe and aesthetically pleasing manner.



  • The main advantages of mini splits are their small size and flexibility for zoning or heating and cooling individual rooms. Many models can have as many as four indoor air handling units (for four zones or rooms) connected to one outdoor unit. The number depends on how much heating or cooling is required for the building or each zone (which in turn is affected by how well the building is insulated). Since each of the zones will have its own thermostat, you only need to condition that place when someone is there. This will save energy and money.
  • Mini Splits are highly efficient, heating and cooling homes at a fraction of the cost of baseboard or wall heaters. Many homeowners are able to cut their heating bill in half. Additionally, since mini splits have no ducts, they avoid the energy losses associated with ductwork of central forced air systems. Duct losses can account for more than 30% of energy consumption for space conditioning, especially if the ducts are in an unconditioned space such as an attic.
  • Mini-Splits are extremely quiet.  Potential noise is eliminated by locating the compressor outside, leaving only the whisper quiet air handler to distribute conditioned air inside.
  • Ductless systems are environmentally friendly as they use R410A refrigerant, proven not to contribute to ozone depletion.
  • Split systems can improve your home’s air quality, as the indoor units have built-in filters that process dust, pollen, and other contaminants. Ducted systems have the potential of accumulating pollutants
  • Ductless mini-split systems are also often easier to install than other types of space conditioning systems. For example, the hook-up between the outdoor and indoor units generally requires only a three-inch hole through a wall for the conduit. Also, most manufacturers of this type of system can provide a variety of lengths of connecting conduits. If necessary, you can locate the outdoor unit as far away as 50 feet from the indoor evaporator. This makes it possible to cool rooms on the front side of a building house with the compressor in a more advantageous or inconspicuous place on the outside of the building.
  • Split-systems can also help to keep your home safer since there is only a small hole in the wall. Through-the-wall and window mounted room air-conditioners can provide an easy entrance for intruders.