How Ductless Mini-Splits Work
A ductless mini-split moves heat instead of blowing air through ducts. Here’s what’s inside, how it’s installed, and what it’s like to live with.
The two halves
Outdoor unit. Holds the compressor and a fan. It moves heat out of the house when cooling, and in many systems, into the house when heating.
Indoor unit. A slim unit, usually high on a wall, with a fan and coil. It blows conditioned air straight into the room.
Line set. Insulated copper lines, a power cable and a drain connect the two through a small hole in the wall, often hidden in a cover outside.
Zones
Each indoor unit has its own controls, so each room or area can be set to its own temperature. Some systems run one indoor unit; others run several from one outdoor unit.
Can ductless heat too?
Yes. We install ductless systems that heat and cool. In heating mode, the outdoor unit pulls heat from the outside air and moves it indoors, even when it feels cold out. Cold-climate units, sometimes called hyper-heat units, are built to keep heating in colder weather, which makes ductless a real option for heat as well as cooling.
Wall, ceiling and floor units
The indoor unit doesn’t have to be on a wall. Wall-mounted units are the most common, but we also install ceiling and floor units, which can fit better in some rooms.
What installation looks like
- We pick spots for the indoor and outdoor units.
- A small opening is made in the wall for the line set.
- The units are mounted and connected. Electrical hookup on new installs is done by a certified electrician.
- We start the system up and show you the controls.
Because there’s no ductwork to build, ductless is often a smaller project than adding central air.
Living with ductless
- Remote or wall control for each indoor unit.
- Filters in the indoor unit that need regular cleaning, as the owner’s manual describes.
- A yearly tune-up to clean and check the system. HVAC Service Plans →
Living alongside a boiler or furnace
A ductless system runs on its own controls, so it doesn’t need to tie into your boiler or furnace. Many homes use it for cooling in summer and extra heat in spring and fall, while the main system carries the coldest days. Others use it to heat and cool a space the main system never reached.
Is ductless right for you?
Ductless is worth a look if you have an older home without ducts, an addition the main system doesn’t reach, or a room that’s always too hot or too cold. ·
How Ductless Mini-Splits Work FAQ
Questions we hear
Are ductless systems noisy?
Can I hide the indoor unit?
Can one outdoor unit serve several rooms?
Who does the electrical work?
Do ductless systems work in the winter?
Does it replace my heating system?
Thinking about ductless?
Planning a new heating or cooling system? C&L Fuel Inc. offers free estimates for new equipment installations and replacements.