How Ductless Heat Pumps Work

Jeff Chapman
Written by Jeff Chapman
Updated June 15, 2021
ductless mini-split heat pump on wall
Ductless heat pumps are more energy efficient than central air systems, and work great for older homes or new room additions. (Photo courtesy of Sara Thompson)

Looking for an energy efficient, green option for heating and air conditioning?

Most people are familiar with what ductwork looks like in a typical ceiling, wall or floor. Those HVAC ducts are there to move warm and cool air throughout a home. But what do you do if you don’t have ducts? 

Historic homes without ductwork

While most homes built in the last 65 years certainly do have ducts, that is not the case in older homes. Those wonderful pre-war homes and apartments have great windows, beautiful floors, interesting woodwork — and heating and cooling challenges. 

For these homes and buildings, ductless mini-split-system heat pumps are a great way to bring modern heating and cooling to these classic structures without tearing up and completely rebuilding walls. 

They are also a good choice when you are adding on to an existing structure like a sun room, where extending the distribution ductwork from the rest of the house is not practical or cost prohibitive.

How do ductless heat pumps work?

In many ways, the ductless unit (also called a mini-split) works like a traditional air-source heat pump. There are two main pieces: the outdoor compressor with a condensing coil and an indoor air-handling unit.

Instead of being installed in a closet or basement, the indoor unit is mounted on a wall.  A conduit links the outdoor and indoor units, recycling the refrigerant as needed. 

The connection between the outdoor and indoor units usually only requires a 3-inch hole through a wall for the conduit. The outdoor unit can actually be placed as far as 50 feet from the indoor unit. So even if you are using mini splits to condition rooms on the front side of a house, you can tuck the condensing units away on the side or back of your home.

ductless heat pump outdoor condenser
The outdoor compressor can be mounted up to 50 feet away from the ductless indoor unit. (Photo courtesy of Angie's List member Terry C. of Pocono Pines, Penn.)

Ductless units offer attractive, convenient solution

The indoor units are designed to blend into your room. They are typically about 7-inches deep with a sleek, high tech exterior. The units can be hung high on a wall, suspended from a ceiling or mounted flush into a drop ceiling. With a hand-held remote control, you can control the temperature in your room from the comfort of your couch. 

ductless heat pump remote control
Control your ductless heat pump system by remote control. (Photo courtesy of member Terry C. of Pocono Pines, Penn.)

Create custom heating and cooling zones

The small units are designed to condition an individual room, so you have an opportunity to create custom comfort zones. Some systems can have as many as four indoor air-handling units, each one with its own thermostat. This allows you to control the temperature in each room. 

Southern facing rooms with lots of windows can get a little more cool air, while rooms throughout the rest of the home do not. And, since each room has its own thermostat, you can actually turn off units in unoccupied rooms, saving energy and lowering your utility bills. 

Energy and money savings

There is one more benefit owners of mini splits enjoy, since there is no ductwork — no energy loss in the ducts! In a traditional forced-air system, you often see as much as 30 percent of the energy consumption lost in unconditioned spaces as the ducts run through attics or crawl spaces. No ducts? No wasted energy. 

Compared to traditional duct central air systems, ductless mini-split air conditioners have a slight advantage in Seasonal Energy Efficient Ratings (SEER). On average, central air systems have a rating between 21 and 18, whereas ductless units range between 23 and 21. 

New HVAC technology requires new skills

At Chapman Heating and Cooling, our technicians have been specially trained to correctly size, install and service these ductless units. If you're in our Indianapolis service area, call us today to see if a ductless heat pump is a good solution for your home.

For those in other parts of the country, do your research and make sure you hire someone who has proven experience installing ductless heat pumps and maybe even ask to speak to a few recent customers to get feedback on their new ductless heating and cooling system.  

As of July 8, 2016, this service provider was highly rated on Angie's List. Ratings are subject to change based on consumer feedback, so check Angie's List for the most up-to-date reviews. The views expressed by this author do not necessarily reflect those of Angie's List.