Ductless Mini Splits vs Central Air Systems

As we approach the hot and humid summer months, many people wrestle over the idea of adding some form of cooling to their home. This then begs the question… “do I look at installing a ductless mini split system or a central air conditioning system.” The answer to that question is not always easy as there are a few big differences between the two. Understanding these differences and how these systems work, will give you a better idea of which type of system would be best for your home. 

What is a ductless mini split system? This type of system consists of an outdoor condensing unit that connects to an indoor evaporative unit (or multiple indoor units) to distribute air conditioning or heat throughout a home. A multi-zone mini split system can include up to 8 indoor units to heat and cool individual rooms with or without the use of ducts which is where the term “ductless” comes from. Each evaporative unit has its own temperature control allowing each room to be controlled individually.  

A central air conditioning system works a bit differently. Like a mini split system, this option also utilizes and outdoor condensing unit. The difference is that this unit connects to a single indoor unit (either an air handler or furnace) and then the air is pushed through a series of ducts throughout your home to distribute the air evenly. Temperature is controlled by a single thermostat. Central air system can utilize a furnace or heat pump to provide heat as well as cooling.

So, now that you know the base differences between mini splits and central air systems, let’s look at the pros and cons of each. 

The mini split systems are smaller in size and fairly easy to install. Most models don’t utilize ductwork for airflow. They just require refrigerant and control wiring connections to the outdoor condenser. These units offer some excellent efficiencies, can provide supplemental heat and the ability control temperatures in individual areas or rooms. On the down side, it often requires multiple units to completely cool a home. In addition, each unit requires two refrigerant lines, a control wire and condensate drain to be run from the evaporative unit to the outdoor condenser. The more units… the more lines on the exterior of the home. Also, some people just don’t like the look of the units hung on the walls.

A central air conditioning system offers a more “hidden” look with registers in either the ceiling or floor as it uses ductwork to move the air. Controlling the temperature is a bit easier as you typically only have one thermostat to deal with. Also, one system can typically serve an entire home (at least where ducts can go). The negative side of this type of system is the ductwork. Ducts can be difficult and time consuming to install. Also, when you retrofit a home with this type of system, there are often places ductwork just can’t reach. 

All in all, when it comes to cooling your home… there are options. A good HVAC company will send out an estimator to do an evaluation of your home. They will measure the rooms in your home and perform a Manual J heat load calculation. This is required, per code, to properly determine the required airflow and amount of cooling (or heating) each room needs. A good estimator will discuss their findings and offer options that work best for your home.