Canadian Woodworking

HomeInOn – ductless heat pumps

Author: Carl Duguay
Photos: Lead Photo by Fujitsu General America
Illustration: Len Churchill
Published: August September 2018

Here’s a way to add a heating and cooling system for homes that lack ductwork and for new high-energy–efficiency homes.


Heating and cooling your home accounts for a large percentage of your annual energy bill. Ductless heat pumps offer a practical option for heating and cooling single rooms where you and your family spend the most time. They work especially well in homes that lack a system of heating ducts and homes with open-concept layouts, where walls don’t separate functional areas such as the kitchen, dining room, living room and basement. They also work well in attached and unattached garages and workshops.

A ductless (aka ‘mini-split’) heat pump consists of three components – a compressor that is located outside the home, a fan unit (aka ‘head’) that is installed in a room within the home, and a remote to control the system. Some compressors can accommodate multiple fan units located in different rooms (zones) of the house. These are referred to as multi-split or multi-zone systems. Depending on the model, fan units can be mounted on the wall, floor or recessed in the ceiling. A number of companies also offer Wi-Fi-enabled heat pumps that can be controlled via your smart device.

Running between the compressor and fan unit are supply and return pipes, communication wires and a drain tube that channels moisture from the fan. Both units need to be electrically powered, which may require installing additional wiring or receptacles. Circulating between the compressor and fan through the supply and return pipes is refrigerant, which absorbs and releases heat. When outdoor temperatures are cold, the refrigerant extracts heat from outdoor air and moves it into the home. In warmer temperatures the process is reversed, and the refrigerant releases warm indoor heat to the outside of the home.

These systems are rated by their heating and cooling output, measured in BTUs. A small system installed in a 500 sq. ft. living/dining room, for example, would put out about 12,000 BTU and usually run on 120V. For a larger multi-split system, where you might have four or five fan units, you would need a 48,000 BTU unit, which would likely require 220V power. In colder climates you’ll still need to rely on auxiliary heating when temperatures fall below the optimal operating temperature of the compressor, which can range from about -5°C to -15°C.

Because ductless systems are so efficient, they have a much shorter payback period than conventional heat pumps. Like any heating system they require annual maintenance to ensure optimal performance. Expect a typical ductless system to last around 20 years.

While an experienced DIYer might be able to install a ductless system, it’s well worth consulting a HVAC professional to ensure you select the right size system for your size of room. Of course, it also makes sense to ensure that your house is as energy efficient as possible before installing a ductless system.


The Compressor
 Fixed to the exterior wall of your home is the compressor. Some compressors can accommodate multiple fan units located in different rooms of the house.

The Fan Unit

To Consider

Here are six features you’ll want to keep in mind when selecting a ductless system. Where listed, typical specifications are for a single-room system.

Air Flow: A measure of air circulation speed in the fan unit, listed in cubic feet per minute (CFM). From 400 to 550 CFM, depending on the speed setting (low, medium or high).
BTU Capacity: A measure of heat energy the system can produce. For cooling, from 9,000 to over 35,000 BTUs, and for heating, from 3,500 to over 35,000 BTUs.
Heating Seasonal Performance Factor (HSPF): A measure of the heat efficiency of a system. From 10 to 14, with higher numbers indicating greater efficiency.
Noise Level: A measure of the decibel rating for the fan unit, usually listed for low, medium and high speed settings. From 15 to 45 decibels.
Operating Temperature: The outdoor temperature below which system performance begins to degrade. From -5°C to -15°C.
Seasonal Energy Efficiency Ratio (SEER): A measure of a system’s cost efficiency. From 20 to 30, with higher levels implying greater value.

Carl Duguay - [email protected]

Carl is a Victoria-based furniture maker and the web editor at Canadian Woodworking & Home Improvement.

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