Autumn in Montréal, with its sunny days and chilly nights, is the perfect transitional season to evaluate the performance of a wall-mounted air conditioner used in heating mode. Many homeowners, condo residents, and building managers wonder whether it's wise to use their wall unit for heating during this time. At AirGreen, we’ve tested, installed, and serviced hundreds of reversible wall-mounted air conditioners, especially in Laval, Longueuil, on the North Shore and South Shore, and we’re here to provide a thorough, real-world analysis.
Understanding the heating capability of a wall-mounted air conditioner
Contrary to a common misconception, a wall-mounted air conditioner, also known as a mini split, is not just meant to cool your home during the summer. Many models, especially from brands like Gree, Fujitsu, Sharp, Tosot, and Bosch, are specifically designed to operate efficiently in heating mode down to outdoor temperatures as low as -25°C.
These models include reversible air-to-air heat pump technology, which extracts heat from the outside air—even when it’s cold—and transfers it inside. It’s a proven, high-performance, and most importantly, energy-efficient solution, especially suited for Québec's autumn when temperatures range between 0 and 15°C.
Why use a wall-mounted air conditioner for heating in autumn?
1. Immediate comfort, without turning on the central heating
In autumn, turning on a central heating system for just a few hours can feel excessive. A wall-mounted air conditioner is the perfect solution to heat a specific room—living room, bedroom, home office—quickly, quietly, and without wasting energy.
2. Lower energy costs
Wall-mounted heat pumps typically use three times less electricity than traditional baseboard heaters. On average, for every kilowatt consumed, they deliver 2.5 to 3.5 kW of heat. This translates into significant savings on Hydro-Québec bills, especially if you regularly use your wall unit’s heating function during the fall.
3. Technology perfectly suited to fall temperatures
Because autumn is a moderately cold season, it aligns exactly with the peak efficiency zone of a wall-mounted heat pump. Where traditional electric systems operate linearly, the heat pump adjusts its output automatically based on the ambient temperature.
Real-life examples of installations by AirGreen
Project in Outremont: A Sharp ZU1 18,000 BTU for a triplex
In a 1930s triplex in Outremont, we installed a Sharp ZU1 18,000 BTU in the main unit on the second floor. The owners wanted to avoid turning on the central gas heating as early as September. Thanks to this unit, they maintain a steady indoor temperature of 21°C in the living room and kitchen without heating the entire building. Result: optimal comfort, silent operation, and an estimated annual saving of $350.
Project in Brossard: Entry-level Gree Lomo for a condo
A retired couple living in a Brossard condo chose a Gree Lomo 12,000 BTU, mainly for summer cooling. During our fall maintenance visit, they told us they were pleasantly surprised by the unit’s heating performance. According to them, the unit was sufficient to heat the entire condo throughout October, without ever switching on the electric baseboards.
What we’re seeing from our clients in and around Montréal
Changing habits
More and more of our clients in Montréal, Laval, Longueuil, and the suburbs are opting for extended use of their wall-mounted heat pump, often through November and even December in some cases. Modern units are increasingly efficient in low temperatures, which is transforming how Quebecers heat their homes.
A noticeable reduction in fossil fuel dependence
Using wall-mounted air conditioners in heating mode significantly reduces the use of gas, oil, or electric baseboard systems, making it not only economical but also environmentally responsible. A large portion of AirGreen’s clients choose these systems to reflect their eco-conscious values.
Things to watch for when using heating mode
1. Regular maintenance
A wall-mounted air conditioner should be cleaned in the fall to ensure the ducts are clear, filters are clean, and that the heating performance is optimal. At AirGreen, we offer a full maintenance service, including gentle pressure washing of wall units.
2. Outdoor unit placement
During our installations, we make sure the outdoor unit is never blocked by leaves or snow. In autumn, it’s crucial to keep the area clear to maintain the heat pump’s efficiency.
Why choose AirGreen for your installation or maintenance?
At AirGreen, our reputation is built on our technical expertise, hands-on experience across Greater Montréal, and our ability to guide clients based on their energy needs and property layout. We don’t just offer a product—we provide a tailored solution adapted to your comfort needs, energy savings, and long-term performance goals.
Our teams install and maintain reversible wall-mounted air conditioners from trusted brands in a variety of settings: primary residences, rental units, urban condos, renovated duplexes, and even small neighborhood businesses.
In summary: Yes, your wall-mounted air conditioner is efficient in autumn!
The idea that a wall-mounted air conditioner is only for cooling is now outdated. Used in heating mode during autumn, it stands out as an efficient, economical, and eco-friendly solution to deal with Québec’s fluctuating temperatures. As long as it’s well-maintained and properly sized, it’s a long-term investment that starts saving you money in September.
A clear call to action: Let’s take the next step together
Looking to optimize home heating without wasting energy? Trust AirGreen, your expert in heat pump installation and maintenance in Montréal, Laval, Longueuil, and the North Shore and South Shore. Contact us today for a free estimate or fall maintenance service for your existing unit.