The art of the ductless mini-split ... the next generation of air conditioning technology

What is a ductless mini-split system?

Before we answer that, let's remind ourselves what a traditional "air conditioning" system is:

1. A fan (or air handler) on the inside of your home - traditionally in an attic or a closet
2. and a compressor (or condenser) on the outside of your house - the thing that makes all the noise.

The compressor sends a hot or cold fluid to the fan (used to be called Freon) via pipes.  The fan then blows air over those pipes (called a coil) and through "ducts" to the rooms of your house (the shinny silver structures in your attic or crawl space).  This is the typical setup for a heat pump, gas furnace, or a "gas pack" - the three most common "air conditioning" systems.

So, back to the original question... what is ductless min-split system.

The anatomy of the phrase:

1. mini: refers to its size.  the fan and the compressor are small, designed to heat/cool ONE ROOM, maybe two, depending on their size,  as opposed to a system that is large enough to heat/cool your entire floor or house.
2. split: just like our example above, the fan and the compressor are split between two locations... one inside, one outside. (some traditional systems are NOT split... the "gas pack" we reference above is not split... both the fan and the condenser are outside in the same location).
3. ductless: this is where the magic happens.  Because the units are "mini", the fan is not in your attic or closet, it is literally attached/hanging on an interior wall, in the room where it is heating/cooling.  This means there are no ducts to collect dust and dirt (and nothing to clean)... and there is no loss of efficiency in the duct work.

Benefits over a traditional system:

1. Control: Because the fan is in the room... you can control the air temperature of just that room.  The fan gets it hot or cold fluid (depending on whether you are heating or cooling), from the condenser outside for JUST THAT ROOM.  Each room that has its own fan so it can be at its own temperature.  Depending on the sophistication of the system, you can even heat in one room, and cool in another. Also, because air is not being moved from room to room, you can control exactly HOW much air you are getting in a specific room... with a traditional system, the only way to control how much air you get in a room is to open or close the vents - and that rarely works well.
2. Maintenance: No ducts - no dust, no dirt, no maintenance.  The air comes right out of the fan and stays in that room.  You can even add specialized filters in the room for hypersensitivity to dust or other indoor air contaminants.  
3. Efficiency: Traditional ducts that run in your attic or crawl space are also insulated to reduce the amount of hot or cold air that is lost while the air runs down those ducts to the next room.  With no ducts... no hot or cold loss - much higher efficiency.  
4. Zoning:  As mentioned above, you can have different temperatures in different rooms.  Zoning is possible with a traditional system, but it often requires expensive (and inefficient) mechanical dampers, electronic controls, and additional maintenance.
5. Space: Because there are no ducts, these systems can be installed in homes with no attics (vaulted rooms) and no crawl spaces (concrete floors).
6. Quiet:  Because the air is coming right from the fan on the wall, it is not required to have a lot of speed (air velocity) in order to maneuver through the ducts... so the fan does not have to turn as fast... making it quieter and more efficient.  Also... because there is no "return vent" (usually called "central air", there is no noise created by air flowing from room-to-room to find that central return vent.
7. Stability: Because the air is coming out of the fan in the room, at a slower speed, and already at the temperature it needs to be at ... the air in the room is more stable with less hot and cool spots congregated around vents in the floors or ceilings.  This is often referred to as "air striation".
8. No vents... no holes in the floor, no holes in the ceilings... air comes right out of the fan.

We use them in small room additions as well as custom homes.  Every home is different, and not every home's floor plan is efficient enough to accommodate this design.

In the end, the units are more efficient in terms of the BTUs they produce to heat/cool, and more efficient in terms of the use of electricity or gas used to run them.

Fan mounted on the wall.  No duct work.  Electronically controlled with a remote.

condenser unit outside