By Stefani Hoffman
Owner Lake Creek Comfort
Mini splits are like the multi tool of home comfort and in the last several years, they’ve come a long way in technology and efficiency for all seasons making them the best option in many cases. A mini split is an ultra-efficient heat pump which provides both heating and cooling to your home. Even in our area of North Idaho, the higher end models will heat efficiently to at least 23 degrees below zero, meaning we are no longer required to have a second heat source. The cost has also come down significantly and in the case of new construction projects they may be even less expensive than your traditional ducted system.
Why is this heat pump called a mini split? Just like a traditional heat pump, the unit is a combination of an air conditioner and a heater. The system is split into outside and inside components. The outdoor unit is smaller than a traditional heat pump and can sit on a pad or be hung up on the building on brackets. Most of these units are much quieter than a traditional air conditioner or heat pump unit when operating.
There can be one to several indoor units which will receive the refrigerant from the outdoor unit and use a very quiet fan to distribute that cooled or heated air inside of your house. If you have a duct system in place, they have air handlers to be used as the inside unit which would distribute the air throughout the home’s ductwork much like your traditional system. If the home does not have a duct system in place, the choice would be a multi-head system indoors to bring the treated air into each living space. The indoor heads can be installed almost anywhere, although an exterior wall is easiest and generally much less expensive. Besides the well-known wall hanging units, there are recessed ceiling cassettes, and ceiling/floor units which are a thin unit that looks much like a wall heater. Some manufacturers even have wall units that have picture frames built in so it can blend in a little more as wall art. There are also ducted indoor units that offer concealed ducts, which can be used if there are several small spaces to condition where we can add small duct runs and still enjoy the efficiency of the mini split system.
A heat pump works by extracting heat or cold from the air using refrigerant. In cooling mode, the system works by the indoor evaporator coil absorbing the heat from the inside space, transporting through the refrigerant lines to the outdoor condenser where a compressor will “squeeze” the heat out of the refrigerant and into the outside air. In heating mode, by reversing the refrigerant circuit, the refrigerant now will evaporate in the outdoor unit and condense or pump the heat into the indoor space. It may be hard to imagine, but there is still some heat in the air, even in subzero temperatures! These modern low ambient, high efficient units are designed to use that heat.
A heat pump is more efficient than a system that is heating the air, whether it is electric heat elements or gas burners. The newer inverter technology used in mini split compressors make them up to 60% more efficient than traditional rotary compressors. The main difference is that a rotary compressor is either on or off, while the inverter compressors run at variable speeds depending on how much heating or cooling is needed, which greatly improves efficiency especially because the turning on and off uses the most energy. Because of the versatility and the control you have for each separate living space or zone, your footprint is much smaller than using a traditional system as well. This zoned system helps prevent energy from being wasted in unoccupied spaces, or in spaces that are already at a comfortable temperature. Many of the brand name systems offer Wi-Fi capabilities, which gives you even more control over your home’s heating and cooling, even when you are not there. They often times have sensors, so the system knows if someone is in the room or not and adjusts the temperature for the areas that are being used.
When you meet with an HVAC contractor to design your system, they are going to look at a lot of things. Which parts of the house need to be conditioned? Is it just an addition or is it a whole house system? How many outdoor units and what size are needed to provide the correct number of BTUs for the size of the conditioned space? How many indoor units and what size do we need to ensure we are able to get the conditioned air to all of the living spaces the homeowner needs? Where will the outdoor units be located? They will prefer to be out of the way, but also need to have fairly easy access to the home’s electrical box. We must also consider wind, drifting snow and water dripping which can build up ice. Where will the indoor units be located? It is best to avoid having your indoor units too close to windows and doors, as this can cause issues with the thermostat since unlike your traditional thermostat location, each of the indoor units has its own thermostat which is one of the benefits that allows us to control each living space. It is best to keep the length of the line set between the outdoor units as short as possible.
Common uses for mini splits are to supplement a traditional ducted system that may not be supplying enough heating or cooling to certain living areas. Mini splits are the go-to for addons and additional dwelling units whether they are above a garage, connected to the main home, or a separate dwelling. Mini splits are a great choice for newly constructed homes since we can save on labor and ductwork. They are also a good choice in the case of a remodel where walls have been moved, rooms have been added and the space has been changed enough that the original ducted system will no longer operate correctly. Duct designs are very dependent on the square footage of a home, the walls and different living spaces where people and appliances will provide loads, the insulation materials in the floors, walls and ceilings, the doors and windows, outdoor conditions such as temperature, direction of the sun, wind, and many other factors. When a remodel is done that changes any or all of these things, that system that was originally designed more than likely will not provide the comfort it was intended to and might even put enough strain on the equipment to end its life. Many of the traditional systems tend to lose up to 30% of the energy through the ductwork, especially if the ducts travel through attics or unconditioned crawls where they can get extremely cold or hot in different seasons. If ducted systems are no maintained, keeping the ducts clean and sealed, they become even more inefficient.
If you are looking at updating or adding a heating and cooling system, take a good look at these versatile, efficient systems. Meet with your local HVAC contractor to see how a mini split system will line up against a more traditional system. In most cases, mini splits can provide a cost-effective and energy efficient way to maintain home comfort year round. There are many rebates offered by local utility companies and several tax incentives as well.