Mini-Split Systems

I have researched various heating and cooling system (HVAC)  for my energy efficient home and decided to use a mini split heat pump. My reasoning is as follows:

  • A Ducted system was more expense and difficultly to install properly, thus robbing the system of its effectiveness and efficiency.
  • A ducted systems take up more space in attics, basements, and other parts of the house.
  • Mini-splits are some of the most efficient systems (up to 26 SEER).
  • Mini-splits come in smaller sizes and can better match the heating and cooling  loads in the specific areas of the house.
  • Mini-split technology has advanced tremendously over the past few years.


What is a ductless mini-split system?
A ductless mini-split system is comprised of an indoor unit called the evaporator and an outdoor unit called the condensing unit.  The evaporator is connected to the condensing unit by copper tubing and electrical wiring which is passed through a 2 ½” – 3” hole.  Basically, it is a small central air unit with the flexibility of cooling or heating one room or more; zoning.

How do the system work?

Like conventional HVAC systems, the mini split system locates the noisy compressor and condenser outside the house. But mini split systems eliminate the need for a basement- or attic-located evaporator unit and bulky ductwork by using thin copper tubing that pumps refrigerant directly to discreet wall mounted blowers inside. Even more remarkable, this same unit works in reverse in winter, absorbing heat from the outside air and moving it indoors to heat your home.

Easy Installation

Copper tubing running through a small 3 to 4-inch opening in the wall or ceiling easily connects the indoor and outdoor units. Refrigerant is cycled through the lines from the outdoor condensing unit to the indoor unit, where the air is quietly distributed to the interior space.

What are the advantages of installing a ductless mini-split over a central air system?
1) With Central Air you must cool an entire home when only one room may need cooling.  On the other hand, ductless mini-splits cool only the areas you want and not the areas you don’t.
2) 18,000 BTU is a typical minimum central air unit.  With ductless mini-splits, you can use 9,000 or 12,000 BTUs.
3) Typical 3-ton homes are not zoned or require complex zoning systems, which makes it very expensive for the homeowner.  With ductless mini-splits, multiple evaporators make zoning as simple as setting a remote control.
4) Energy wasted in long lengths of uninhabited ductwork means higher energy bills.  Less than 5% cooling loss occurs in insulated refrigerant lines compared with up to 25% through ducts.
5) Retrofitting homes requires cutting holes in walls, floors, ceilings or decreasing closet space with ducts.  Ductless mini-splits requires just a 3 or 4” diameter hole in the outside wall.  Means less mess and better home aesthetics.

What is SEER?
Seasonal Energy Efficiency Ratio; a measure of cooling efficiency for air conditioners and heat pumps.  The higher the SEER, the more energy efficient the unit.  Energy efficiency equates to lower electrical bills.  Currently U.S. Government’s minimum SEER rating is 13. 

What is a BTU?
British Thermal Unit.  Used to measure cooling or heating capacity;  the amount of heat required to raise or lower the temperature of 1 lb of water 1°F.

From the many mini splits available I chose Fujitsu.

The Fujitsu Mini Split Heat Pumps/Mini Split systems typically use much less electricity than other electric units and can save money on your monthly electric bill while helping the environment. Fujitsu Mini splits are smaller than others I researched, which is a major benefit if you’re building a smaller home or designing smaller zones. This Mini Split systems is also very quiet while running, which is a great advantage if you have young children, difficulty sleeping, live in close proximity to others, or simply enjoy the peace and quiet.

The links that follow are some of the research I used to make my determinations; there are many more, just Google “mini split heat pump systems”.

Comments and Recommendations for Mini-Split Air Conditioner and Heat Pump Systems

by Keith A. Temple, P.E.

Ductless, Mini-Split Heat Pumps at

by US Department of Energy

Ductless Mini-Split Heat Pump Comfort Evaluation 

by K. Roth, N. Sehgal, and C. Akers

Green Builder Chooses Mini-Splits for Whole-House HVAC

Case Study Fujitsu

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