What is a mini split heat pump and how does it work?
If you’re researching energy-efficient ways to heat and cool your home, you may have stumbled upon something called a mini split. So, what is a mini split heat pump and how does it work? How is it different from a traditional furnace, radiator heat or heat pumps? Let’s dig in.
Industry experts may also refer to these energy-saving, two-in-one heating and cooling units as ductless heat pumps or ductless mini splits. (Looking for more information about conventional heat pumps, AKA dual fuel heat pumps and air source heat pumps, check out this article.)
We know it’s known by many names but what exactly is a mini split, and how does it work? Let’s find out! This article covers everything you need to know — from how mini split systems operate to why they’re a smart choice for homeowners looking to save energy, lower energy costs and increase comfort.
Find even more ways to save on energy. Take a free DIY Home Energy Assessment today.
What is a mini split heat pump?
A mini split heat pump is a fully electric heating, ventilation and air conditioning (HVAC) system that provides both heating and cooling. Unlike traditional central HVAC systems that rely on ductwork to distribute air throughout your home, ductless mini splits consist of two main components: an indoor air-handling unit (AKA the head unit) and an outdoor compressor/condenser combo.
These units are connected by a small conduit that houses the power cable, refrigerant tubing, suction tubing and a condensate drain.
Because they don’t require ducts, mini split heat pumps are often used in homes or buildings where installing or extending ductwork would be difficult or expensive — such as older homes, homes without existing ductwork, home additions, garages, detached accessory dwelling units (DADUs) or finished basements.
How does a mini split heat pump work?
A mini split heat pump uses the same basic technology as your refrigerator or traditional air conditioner; however, instead of generating hot or cool air, it transfers heat into or out of your home.
In the summer, refrigerant extracts heat from inside your home (expansion) and pumps it outside, where the heat is squeezed out (compression). In the winter, the compressor works as an evaporator, and the cycle is reversed.
Mini split cooling mode:
- The indoor unit absorbs and extracts heat from the air inside your room using a refrigerant-filled coil.
- The refrigerant carries — or pumps — the heat outside to the outdoor unit.
- The outdoor unit squeezes the heat out of the refrigerant and releases it into the outside air.
- Cool air is blown back into your room.
Mini split heating mode:
- The process is reversed.
- The outdoor unit pulls heat from the outside air — even in cold temperatures.
- The refrigerant carries this heat inside.
- The indoor unit pumps warm air into your space.
Thanks to this heat transfer process, mini split heat pumps are highly energy efficient, using 60%-70% less energy to heat your home than a traditional heating system like an electric furnace or radiator.
What are the benefits of a mini split heat pump?
1. They’re energy efficient.
Because mini splits don’t lose energy through ducts (which can account for up to 30% of energy use in traditional systems), they’re often more efficient than ducted HVAC systems. Many models are also ENERGY STAR®-certified and use inverter technology to adjust power use based on the current heating or cooling need.
2. You have more control over temperature zones in your home.
Mini splits give you the power to control the temperature in individual rooms or “zones.” Each indoor unit operates independently, so you can heat one room while cooling another, or turn off units in rooms that aren’t being used.
3. They’re (relatively) easy to install.
Without the need for ducts, mini split systems can be installed by qualified professionals in a variety of places. Wall-mounted units are the most common head unit, but there are also ceiling-recessed and floor-mounted models available.
Looking for a trusted HVAC contractor? Hire a contractor with confidence when you work with a TVA-vetted member of the Quality Contractor Network (QCN).
4. They’re quiet.
Mini split systems are praised for their quiet performance. The noisy compressor stays outside, and the indoor units are designed to operate with minimal sound, making them great for bedrooms, offices or media rooms.
5. They can help lower your energy bill.
While the upfront cost of a mini split system may be higher than a traditional window unit or space heater, the long-term savings in energy costs can be significant, especially if you’re replacing outdated, inefficient systems.
ENERGY STAR notes that “a typical household’s energy bill is around $1,900 annually, and almost half of that goes to heating and cooling.” ENERGY STAR-certified heat pumps are independently verified to save you energy and money, plus they use up to 60% less energy than standard home electric radiators.
How many indoor head units do you need?
One outdoor mini split unit can typically support up to four or five indoor air handlers, depending on the capacity of the system. The number of units you’ll need depends on the size of your home and how many zones you want to control individually.
Other sizing factors include your home’s ceiling height, number of occupants, doors and windows, and how well (or poorly) your home is insulated. (Need an insulation upgrade? Insulation and air sealing rebates are available.)
Your TVA-vetted QCN contractor can help determine the correct size and number of head units for your space using a load calculation based on square footage, insulation, window size and other factors.
What are the disadvantages of mini splits?
While there are a lot of benefits to installing a mini split, there are a few potential downsides to consider:
- Initial Cost: Installation can be more expensive than a window unit or baseboard heater.
- Aesthetics: Some homeowners don’t love the look of wall-mounted indoor units.
- Maintenance: Filters need regular cleaning and professional service is recommended annually.
Is a mini-split right for you?
If you’re looking for an energy efficient, flexible and powerful way to heat and cool your home, a mini split heat pump could be a smart choice. They’re especially well-suited for homes without ductwork, spaces with specific comfort needs and smaller homes.
