In some residential buildings in Ville-Marie , especially modernized condos and plexes, heat pumps aren't always installed on the ground in a backyard. Very often, the best option—and sometimes the only one—is to mount the outdoor unit on a flat roof . This is exactly the type of configuration we implemented here: a clean, stable installation designed to last, despite exposure to wind, rain, and Quebec winters.
At AirGreen , we love these urban projects: they demand more rigorous preparation, particular attention to the building's airtightness, and a very methodical approach to cable routing and acoustics. The result: reliable comfort, without compromising on aesthetics or performance.
A HVAC solution tailored to the condos of Ville-Marie
Ville-Marie is a mix of heritage buildings, condo blocks, and residential towers. You'll often find:
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condominiums with strict regulations (noise, appearance, location of equipment)
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limited outdoor spaces (no yard, no easy access to the ground)
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access constraints (stairs, roof hatches, elevators, building opening hours)
In this context, the wall-mounted heat pump remains one of the best solutions: quiet, efficient, and ideal for air conditioning in the summer while heating during the cold seasons.
Type of machine installed
Here, we are talking about a:
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Wall-mounted heat pump (mini-split / wall unit)
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Brand: Gree Charmo (brand provided)
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Model: Charmo (consistent with the range, and used as a reference for the system)
This type of system is ideal for condo units, upper floors, and homes where you want to quickly improve comfort without redoing the entire air distribution system.
What we see at the installation (salient details)
In the photo, several elements speak for themselves — and they tell the story of a seriously executed installation:
1) Outdoor unit mounted on a raised support
The unit is installed on a stable metal stand , with sufficient height to:
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limit the risks associated with standing water and snow
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preserve airflow around the condenser
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avoid direct contact with the roof membrane
This approach is crucial on a flat gravel roof: it protects the equipment and the building envelope.
2) Weather protection during the intervention
An AirGreen umbrella is visible above the work area. This detail is important: during operations (vacuum sealing, testing, loading/validation), it's crucial to prevent water from seeping into connections, tools, or interfering with certain procedures. On the roof, the weather changes rapidly.
3) Manifold check (pressure reading)
Connected pressure gauges indicate a verification/commissioning stage:
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validation of operating pressures
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stability control
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confirmation of system behavior under real-world conditions
This is a key step to ensure that the Gree Charmo heat pump delivers its expected performance and that it will not be “over-stressed” in the first few weeks.
4) Line switching management
Even if the interior is not visible, a rooftop installation almost always involves:
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a well-planned route for the refrigeration lines (with mechanical protection if necessary)
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a discreet route to preserve the facade's aesthetics
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special attention to penetration points (waterproofing, sealing, fireproofing as needed)
The challenges of a flat roof installation (and how to manage them)
Installing an outdoor unit on the roof isn't "just a different location." It changes the way you work, and especially the points that need to be secured.
Waterproofing and respect for the building envelope
On a flat roof, the priority is simple: zero compromise on waterproofing . At AirGreen, we:
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chooses fixing and support methods that minimize the risks
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avoids improvisations on the membrane
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protects high-traffic areas to reduce wear over time
Vibrations and noise
In a condo, noise travels quickly through the structure. To limit vibrations:
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a stable support is preferred
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We plan to use suitable anti-vibration interfaces (as appropriate).
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We choose a location that respects distances and sensitive areas (rooms, shared walls)
The goal: comfort without nuisance , for both the customer and the neighbors.
Accessibility for maintenance
A heat pump isn't something you simply "install and forget." On a rooftop, you're already thinking about future visits:
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secure access
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space around the unit to clean the coil
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logical positioning to allow for quick intervention if an adjustment is required
Why the Gree Charmo is a good choice in an urban setting
In a reality like Ville-Marie, we want a system:
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efficient in air conditioning during heat waves
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effective for heating during the cold seasons
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reliable, stable, and pleasant to use every day
The Gree Charmo (depending on the configuration) fits this logic well: it is a wall-mounted heat pump designed to offer a good balance between performance, comfort and noise level — a trio that is particularly important in a condo.
AirGreen's best practices for this type of construction site
When installing a wall-mounted heat pump on a flat roof, here's what makes the difference between "it works" and "it works perfectly for a long time".
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Thoughtful positioning : air clearance, distance from sensitive areas, future access.
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Support and stability : elevated installation, surface protection, solid structure.
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Quality of connections : tightening torque, sealing, pressure tests/commissioning.
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Clean finish : protected lines and discreet route (important in a condominium).
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Complete validation : pressures, operation, actual efficiency, behavior in heating/cooling mode.
That's exactly what we're aiming to deliver: a clean, sustainable, and optimized installation.
What to expect after installation
Once the system is operational, the customer typically benefits from:
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stable air conditioning even on humid days in Montreal
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efficient heating during autumn, spring and a good part of winter (depending on configuration and use)
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better distributed comfort, without electric radiators that overheat one room and leave another cold
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a discreet solution, adapted to the urban lifestyle
And above all: the peace of mind of a properly installed system, with logical access for maintenance.
Recommended maintenance (simple, but essential)
To maintain the performance of a Gree Charmo wall-mounted heat pump :
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clean the filters of the indoor unit regularly
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Keep the outdoor unit clear (of leaves, debris, ice depending on the season)
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Schedule periodic maintenance (coil cleaning, general checks)
On the roof, maintenance becomes even more important, as the wind can bring dust, fine gravel and particles that accumulate.
Conclusion: an urban installation, built to last
This installation in Ville-Marie perfectly illustrates a common reality in Montreal: when ground space is limited, a flat roof becomes the logical location—provided it's done correctly. With elevated support, rigorous commissioning, and an approach that respects the building envelope, a Gree Charmo wall-mounted heat pump can offer remarkable comfort, both summer and winter.
At AirGreen , that's exactly what we aim for: clean construction sites, solid technical decisions, and a result that "fits" with condominium living.