So you've been researching HVAC lately and you're thinking about upgrading the system in your home. While researching you learned about "mini-splits" but you also learned that not all mini splits are created equal. So, can all mini splits heat and cool? No, but some can. Ones sold near you most likely can if you live in a climate that would need both heating and cooling.
In North America because temperatures vary so dramatically, it is typically necessary to have a mini-split that is able able to heat and cool. But, like I said, not all are created equal. And it depends on the manufacturer. Always read the specifications.
What You're Actually Getting
Each mini split system will have two main components, an outdoor unit which houses the compressor and condenser and an indoor air handler which houses a copper butterfly coil. Refrigerant in a copper line runs through this coil, then the air in your home runs over this coil, and in turn, energy is transferred between the air and the refrigerant. Through this same principal, the outdoor unit will reverse the original temperature change / energy transfer and the system can then push more refrigerant through the lines and your home stays cool in the summer and warm in the winter. These lines are small and can run long lengths. Which is why no ductwork is required, and is also why these systems tend to be more efficient.
This makes mini splits great for older homes without existing ductwork, garage conversions and room additions. Running ductwork can be expensive and sometimes even requires a full remodel. In a scenario like this, a ductless mini split would be the perfect choice.
Another common scenario might be homes that have spaces that are always too hot or too cold even with the main HVAC system running. Often times in a situation like this a mini split is the cheapest option. Not sure what size you need? Use our HVAC load calculator to find out.
People Are Skeptical About Heating
Most people are used to the idea of an air conditioner blowing out cold air inside and warm air outside, but how can an air conditioner heat up the inside of my home when it's cold outside!?
Well, refrigerant in an ac system actually runs off the boiling point principal. When a refrigerant boils, this create a change in state, which requires more energy than just a change in temperature. Also, refrigerant will boil at much lower temperatures than water. Different mixes have different temps, but well below 0 degrees F is typical.
Pressure also affects boiling point, and this is where things get slightly complicated. To put it simply, an air conditioner will change the pressure inside the ac units so that it will boil at a lower or higher temperature, depending on the climate and what the user sets on the controls. An example of this thats easier to understand, is the difference in boiling point of water at different elevations. At sea level, water boils at 212 degrees F, at 5000 feet elevation (Utah or Colorado for example) water boils at 202 degrees F.
So for your home to cool down, refrigerant heats up inside your indoor unit, and cools the air around it that is inside your home. Powered by not only the change in temp, but also the manipulated change in state. When you then need to heat your home, this flow is reversed and you start
Cold Climate Performance
There are limits to the performance of these mini splits in cold climates. As the air gets colder outside, it gets harder to heat up the refrigerant to the required temperature. In other words, there is literally less heat in the air you are trying to use to heat something up.
We have made some big improvements in recent years though. Depending on the model, mini splits operating range varies from a low of 5°F down to -13°F for ultra cold climate units.
These cold climate models usually cost 20-30% more than regular units. In northern states with cold winters they can be very effective, but for most climates in North America, a normal mini-split will do.
Efficiency Numbers
Other than the ease of install, efficiency is what sets mini splits apart from a central heating and air system.
Most homes have ducts that run to every room. Air from the indoor central unit is pushed via a large blower through the main duct system and pushed into these rooms. The problem is, there is energy loss throughout these ducts. Heat can penetrate ducts in the summer, and it can escape from them in the winter.
You might ask, well what about the energy loss from the copper lines that run from the outdoor unit to the indoor unit? Well, all AC units with the exception of through the wall or window mounted units, already have line sets. And the loss from line-sets is minimal compared to ducts. The ducts alone in central systems make ductless mini-splits on average 30 percent more energy efficient.
The Downsides... What Are the Tradeoffs?
Mini splits will often cost more upfront compared to a similar size central system. Now-a-days though, we have more DIY mini split systems on the market that can potentially save you more than $1000 by just installing the unit yourself.
The trade off would be more labor for you.
Bottom Line
Mini splits heat and cool effectively, and they offer efficiency gains that meaningfully reduce energy costs. For homes without ductwork or with airflow problems in certain rooms, they should be a serious consideration.
Ready to learn more? Browse mini split systems | Calculate your BTU needs | Compare mini split vs central air
