Comparing a Mini Split to a Central Air Conditioning System
In both a ductless mini split and a typical central air conditioning or A/C system, there’s an outdoor unit and an indoor unit connected by a refrigerant line. The refrigerant cools the inside air, collects heat and humidity and then runs to the outside unit which exhausts the heat to the outdoors. The outdoor unit cools the refrigerant and it runs back inside to again cool the air and collect heat.
The main difference between a mini split and a central air system is the need for ductwork. A traditional central air conditioning system sends the cool air throughout the house using a system of ductwork that connects to vents in multiple rooms of the house. As the name implies, a ductless mini split or mini split A/C system doesn’t require ductwork. The indoor unit sends chilled air directly into a specific room.
Some common situations when you might consider a mini split include:
- A home where it’s not practical or not possible to install ductwork for a central system
- A new addition or newly finished area
- A home where you want to set up cooling and heating zones to reduce energy costs
Beyond the need for ductwork, here are some other factors to consider when deciding between these two cooling systems:
Placement and Size
- The indoor unit for a central air system is usually in an attic, basement or crawlspace. The interior component of a mini split air conditioner is mounted on the wall.
- The indoor portion of a central system is larger than that of a mini split, but it’s out of sight. The interior component of a mini split A/C is comparatively small, but you’ll have one in every room you’re cooling.
Maintenance
- A typical mini split has a filter you should clean every 14 to 45 days. You may also need to clean dust from the indoor unit. A typical central air unit has a filter that you’ll need to replace every 30 to 90 days, depending on the filter type. For both systems, make sure the outside of the exterior unit is clear of debris such as leaves and grass clippings. Keep the area around the unit free of grass, weeds, shrubs, etc.
- Both systems require annual checks from a professional for good operation and efficiency. With central air conditioning, however, you may also need to have the ductwork professionally cleaned from time to time.
Heating
- Both ductless mini splits and central air systems can use a heat pump to warm your home in cool weather. The heat pump uses the indoor and outdoor units to warm your home; the refrigerant delivers heat indoors rather than exhausting it outdoors. The system sends the heated air through the central air ductwork or the mini split indoor unit.
- A furnace is an alternative method of heating with a central air system. It’s an additional piece of equipment that uses electricity or a fuel such as natural gas or propane to heat the interior air. The air then travels through the ductwork to heat the home.
What Are Advantages and Disadvantages of a Mini Split System?
Traditional central air systems are relatively common, but you may not be familiar with the pros and cons of a mini split air conditioning system.
Advantages of a Mini Split A/C
- Efficiency: Mini split systems typically use electricity more efficiently than a traditional central system, so they tend to use less power for comparable cooling.
- No Ductwork Needed: Without ductwork, you won’t have to worry about cooled air leaking from the system or picking up heat as it travels through the ducts.
- Cool Air Exactly Where You Want It: Since a ductless system uses an indoor unit to cool a room, you can easily set it to cool only the spaces you’re using. This multi-zone cooling gives you better control over your home temperatures and keeps you from wasting energy cooling empty rooms.
- A Solution for Add-On Spaces: The efficiency and control a ductless system offers makes it a good cooling solution for a new addition to your home or for an attic or basement you're converting into a living space. You’ll be able to cool the space without the expense of installing ductwork and you won’t overtax an existing central system by adding a new cooling load. The mini split can work with an existing central system to keep the entire house comfortable.
- Easier Installation: While a central air system requires professional installation, some ductless mini splits are designed for do-it-yourself installation by an experienced DIYer. Codes in some areas require installation by a licensed professional, so follow the code for your area.
Disadvantages of a Mini Split A/C
- Appearance: While a central cooling system sends cool air out into a room through relatively small and inconspicuous registers, the indoor unit on a ductless system is fairly prominent and you may find it unattractive. If you’re cooling more than one zone, you’ll have several wall-mounted units throughout the house.
- Air Filtration: The air filter on a central system can catch dust, pet dander, pollen, mold spores and more and helps clean the air in your home. While mini splits have filters, they may not clean the air as thoroughly as a traditional system with a high-efficiency filter.
- Cleaning: The filters on a ductless system often require more regular cleaning than a standard central system. If you use a mini split system regularly, you may need to clean the filters every couple of weeks.
- Cost: The A/C unit cost for purchasing a ductless system will usually be higher than that of a central system that can cool the same area. However, this comparison assumes that the central system can use existing ductwork. Installing ductwork would significantly increase the total cost of a central system.
Do Ductless Mini Splits Use a Lot of Electricity?
Energy consumption for both types of cooling systems can vary greatly by climate and your temperature preferences, but a ductless mini split can use electricity more efficiently. For example, the compressor on a mini split system can run at variable speeds, speeding up and slowing down as needed and consuming less power when cooling needs are lower.
And, as discussed above, the lack of ductwork can make a mini split more efficient. You won’t have to worry about losing chilled air in the ductwork and wasting the power you used to cool it.
How Much Does a Central Air Unit Cost?
While cost varies by location and what’s included, a central air system with both indoor and outdoor equipment can cost from $1000 to $5000 or more before installation. Large homes need larger systems and will have an A/C unit cost at the upper end of the price range. If you need to install a duct system, the ductwork will be a significant added expense. You may also need to add a furnace to the system.
Ductless mini split systems have a greater initial cost than comparable central systems, but they often include heating functionality. The efficiency of a mini split can help you save on energy costs over time, particularly if you don’t need to cool your entire house all the time