In the Saint-Laurent borough, we recently installed a Gree Charmo heat pump in a unique setting: an outdoor unit mounted on a gravel roof , typical of commercial buildings and some flat-roofed plexes/condos. This type of installation requires a methodical approach, as we need to protect the roof membrane , ensure perfect stability , minimize vibrations , and guarantee easy access for maintenance , both in summer and winter.
At AirGreen , we often see clients who want a reliable HVAC solution without compromising on durability. The Gree Charmo line fits perfectly into this philosophy: a modern wall-mounted heat pump (mini-split), designed to offer consistent comfort, good energy efficiency, and precise temperature control—particularly important in Greater Montreal where temperature variations are extreme.
A construction site on a flat roof: a common reality in Montreal
In Saint-Laurent, several buildings have gravel roofs with curbs (parapets) and technical areas already used for mechanical equipment. Installing an outdoor unit in this environment requires adhering to very clear priorities:
-
Do not puncture or damage the membrane (and thus avoid leaks)
-
Distribute the load over a stable base (and not directly onto the gravel)
-
Prevent the transmission of vibrations within the structure
-
Plan for a positioning that allows good air circulation around the condenser.
-
Enabling quick service without unnecessary gymnastics or dismantling
Visually, the outdoor unit is mounted on a raised support (metal structure) resting on load-bearing pads , with wooden elements providing stabilization and leveling on the uneven roof surface. This is exactly the type of installation preferred when a clean, stable, and durable result is desired.
Type of machine installed: wall-mounted heat pump (mini-split)
Although the photo mainly shows the exterior, the overall configuration is very common: a wall-mounted heat pump with:
-
an outdoor unit (condenser) on the roof
-
an indoor wall unit (evaporator) inside the building
-
a refrigeration connection (insulated piping) and the electrical supply routed neatly
This format is particularly popular in Montreal, Laval, Longueuil, the South Shore and the North Shore because it offers an excellent compromise between cost , comfort , efficiency and ease of installation .
Brand and model: Gree Charmo
The installed unit is a Gree Charmo . In practice, this type of heat pump is chosen for:
-
operational stability (more consistent comfort)
-
good heating capacity for our transitional seasons (autumn, spring)
-
efficient air conditioning in summer, even during periods of humid heat
-
This approach is generally appreciated for projects where a reliable solution is needed, but without resorting to a complete central installation.
At AirGreen, we always adapt the choice of system to the specific characteristics of the building: insulation, orientation, areas to be served, installation constraints, and lifestyle or occupancy patterns. In Saint-Laurent, we often encounter mixed-use spaces (offices, light workshops, apartments above), and the wall-mounted heat pump remains a very flexible option.
Key installation details: stability, vibration, and roof protection
1) Elevated support: essential on roofs
On a flat, gravel-covered roof, placing a unit directly on the ground is rarely a good idea. Here, the unit is mounted on an elevated structure which allows:
-
to limit the accumulation of snow around the condenser
-
to keep the bottom of the unit more unobstructed during freeze/thaw cycles
-
to improve access for inspection and maintenance
2) Load distribution: protect the membrane
We've noticed a base that distributes the pressure over a wider area. This is good practice because the concentrated weight of HVAC equipment can, in the long run, create weak points on the roof. In our installations, we always aim to reduce point loads , especially on commercial roofs.
3) Vibration management: comfort + longevity
Even a well-designed condenser generates vibrations. If these vibrations are transmitted to the building, a humming sound can be heard inside—and this can accelerate wear and tear on certain components. Mounting the condenser on a support and ensuring a stable base generally allows for:
-
a reduction in perceived vibrations
-
quieter operation
-
better long-term behavior
4) Clearance and air circulation
On a roof, you might be tempted to "hide" the unit near a parapet. We prioritize efficiency: we ensure the unit has enough space to draw in and expel air properly. Poor airflow means the system has to work harder, consumes more energy, and can lose performance during peak demand.
Why this type of installation is particularly relevant in Saint-Laurent
Saint-Laurent combines highly urban areas, industrial zones, and mixed-use buildings. The constraints are often:
-
Limited access to the backyard or balconies
-
aesthetics to be respected on the facade
-
need to avoid noise from the neighbors
-
roof already designed as a technical area
Installing the outdoor unit on the roof then becomes a logical solution, provided it's done correctly. And that's precisely where expertise makes all the difference: a hasty installation can create problems (vibrations, drainage issues, difficult access, premature wear, risks to the roof). A clean, well-planned, and stable installation results in a reliable and easy-to-maintain system.
Maintenance and best practices: what to anticipate from the installation stage
A wall-mounted heat pump like the Gree Charmo will perform best if maintenance is simple and regular. For rooftop installations, the following should be considered from the outset:
-
leave space to clean the outer coil
-
facilitate the verification of connections and support
-
Plan for a rapid response in case of ice, debris, or seasonal obstructions.
-
Ensure that the area around the unit remains clear (leaves, dust, displaced gravel, etc.).
Inside, maintenance (filters, cleaning, general inspection) remains crucial for air quality and energy efficiency.
The result: a clean, stable installation ready for Quebec's seasons.
This Gree Charmo installation in Saint-Laurent perfectly illustrates our approach at AirGreen:
-
a smart choice of location (technical roof)
-
a stable and roof-friendly installation
-
an installation designed for maintenance, durability and comfort
-
an efficient solution for heating and air conditioning in Greater Montreal
Whether you are in Montreal , Saint-Laurent , Ville-Marie , Ahuntsic , Laval , Brossard , Terrebonne or Longueuil , we apply the same standards: a clean, efficient installation, designed to last.