Ductless mini-splits are a superb way to heat and cool your home. They are very efficient and easy to install, making them the preferred choice for many home owners.
Mini-splits are more efficient than central air systems, partly because they have no ductwork, which is responsible for energy losses of around 30% in a typical ducted system.
You might have heard that they can require different voltages, which then begs the question of which voltage requirement is better for your needs. The electrical requirements for mini-splits are straightforward, but you must ensure you comply with the relevant codes.
Keeping on the right side of the inspector keeps you and your family safe, your system operating correctly, and helps prevent issues that could cause problems further down the line.
This article details the voltages used by common models of mini-split heat pumps and some considerations related to wiring. So read on to find out more.
What Voltage Do Ductless Mini-Splits Typically Use?
Ductless mini-splits generally require 220 volts, but some smaller models only require 110 volts. Mini-splits also need to be installed on a dedicated circuit with a disconnect box to allow the power to be cut off for servicing and repair work.
For a reminder of the differences between ductless mini-split heat pumps and ducted central air, why not read our article comparing the two systems?
What Is a Ductless Mini-Split?
Before we get into the voltages that different types of mini-split use, let’s remind ourselves of the basics.
A ductless mini-split is a type of heat pump that is permanently installed in your home as a means of heating and cooling. A mini-split system is “split” into at least two main parts—an outdoor unit and one or more indoor units, also known as air handlers or head units.
These distinct components contrast with a packaged heat pump or AC unit, containing all the system mechanisms (the condenser, compressor, and evaporator) in a single unit.
The mini-split’s outdoor unit houses the compressor and one of the coils that serves as a condenser or evaporator, depending on the mode of operation.
The indoor unit contains the other coil, used as the evaporator when the system operates in cooling mode, and the condenser in heating mode.
The two units are connected by refrigerant line sets that convey the refrigerant around the system. Electrical cables facilitate communication between the outdoor and head units and provide power.
There is also a condensate drain used to get rid of condensate generated by the indoor units. The line sets, cables, and drains are usually enclosed in conduit to protect them from the elements and passed through a three-inch hole in the wall, making installation simple.
Ductless Mini-Splits Need a Dedicated Circuit
Mini-splits must be installed on a dedicated circuit to prevent circuit overloading and repeated circuit breakers tripping.
The National Electrical Code (NEC) sets the benchmark for the safe design, installation, and inspection of electrical work in all 50 states of the US. The NEC states that all major, fastened-in-place electrical appliances, including ductless mini-split heat pumps, require their own dedicated circuits.
This allocation is necessary to prevent circuit breakers from tripping when attempting to run too many appliances simultaneously. A dedicated circuit has its own circuit breaker in the electrical box, which helps to prevent circuits from overloading and tripping breakers continually.
Domestic outlets in the US provide 110 volts, the same voltage as some of the smaller ductless mini-split heat pumps. So, you might think you could put a mini-split that requires this voltage on the same circuit.
However, you are risking problems if you do this. Although small 110V units are tiny in terms of Btu, they contain many components that draw power, which can quickly add up.
The key metric you need to consider for your wiring is the Minimum Circuit Ampacity (MCA). The MCA is the maximum current that a wire can carry continuously without exceeding its temperature rating.
Start-up amperage is high when your mini-split first kicks in when it is likely to draw a much larger current than under standard operation. If someone is using a hairdryer on the same circuit when this happens, you might have a breaker trip.
Obviously, the more appliances you have on the same circuit, the more likely these complications will be. So always put a mini-split on its own dedicated circuit.
Should I Choose a 110V or 220V Mini-Split?
Depending on the system size you need, you might not have a choice.
Large mini-split systems (12,000 Btu or above) require 220V to operate. These more extensive systems need more power to fulfill their heating and cooling outputs.
On the other hand, smaller mini-split systems that provide heating and cooling for a single zone (say, 12,000 Btu or less) can come in 110-volt or 220-volt versions.
If you go with the 220V model, you will need to draw fewer amps, which means you can use a smaller wire in the installation. This benefit will save you some money, mainly if you run the wire over a long distance.
There is also a minor theoretical efficiency gain if you opt for the higher voltage, lower amperage system. This gain is because the power lost is proportional to the current squared, multiplied by the resistance of the wire.
The equation is as follows:
P = I2 • R
Where P = Power (Watts); I = Current (Amps); R = Resistance (Ohms).
So, drawing lower amperage results in less power loss which is why transmission cables used in the power grid operate at such high voltages—high voltages result in low amperages, minimizing power loss during transmission.
However, the difference between a 110V and 220V mini-split results in a negligible difference in power loss in the supplying wires. If both units are rated at the same Btu with the same HSPF and SEER ratings, they will use a similar amount of power to heat or cool your home.
The difference in the amount of power lost in the wires providing electricity to the units is minimal. Therefore, the amount of money you would save over the unit’s lifetime using smaller gauge wire is insignificant.
If you’re interested in saving money on your electric bills, you would be much better off following the advice in our article that covers 15 reasons your electricity bill is so high.
Summary
Ductless mini-splits are an effective and efficient way to heat and cool your home.
Small mini-splits capable of heating a single zone can come in 110V or 220V models, but larger units (above 12,000 Btu) are only available in 220V.
All mini-splits require a dedicated circuit to prevent overloading issues and stop repeated breaker tripping.
There is no difference in the efficiency of mini-splits when choosing a 110V or a 220V model. If both units have the same efficiency ratings, their performance will be the same regardless of what voltage they use.
