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Installation of a Gree Charmo wall-mounted heat pump in Ville-Marie (Montreal): performance, discreet installation, and meticulous rooftop installation

In Ville-Marie, AirGreen installed a Gree Charmo wall-mounted heat pump with an outdoor unit on a gravel roof: raised support, insulated pipes, vibration management and discreet integration for four-season comfort in the heart of Montreal.

By AirGreen Climatisation & Chauffage Admin6 min read
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Installation of a Gree Charmo wall-mounted heat pump in Ville-Marie (Montreal): performance, discreet installation, and meticulous rooftop installation
Installation of a Gree Charmo wall-mounted heat pump in Ville-Marie (Montreal): performance, discreet installation, and meticulous rooftop installation
The full story

The article, chapter by chapter

In Ville-Marie, flat-roofed buildings and modern condominiums often present a unique challenge for HVAC systems: year-round comfort is desired without cluttering balconies, compromising aesthetics, and respecting technical constraints (access, clearances, vibrations, noise, drainage). It was precisely within this context that we installed a Gree Charmo wall-mounted heat pump , with an outdoor unit positioned on a gravel roof .

The photo clearly shows the Gree Charmo outdoor unit (condenser) with the Inverter designation, an AHRI Certified sticker, and our AirGreen Air Conditioning & Heating label. You can also see a clean installation of the refrigerant lines, protected by white insulation, and a raised support designed to stabilize the equipment above the roof surface.


Why choose a Gree Charmo wall-mounted heat pump in Ville-Marie?

In Ville-Marie, one often encounters:

  • condos where interior space is precious;

  • condominium rules regarding noise and visibility;

  • air conditioning needs in the summer (urban heat island) and efficient heating in the mid-season, or even in winter.

The Gree Charmo wall-mounted heat pump responds very well to these realities thanks to Inverter technology (power modulation) which helps to maintain a stable temperature, reduce on/off cycles, and promote more constant daily comfort.

For our clients, the goal is not just “to have cold air”: it is to obtain a system that heats and cools , that remains discreet , and that integrates well with the typical constraints of a building in Ville-Marie.


Type of system installed: wall-mounted heat pump (mini-split)

The type of machine here is unambiguous: the compact outdoor unit, with an axial fan and a "block" format, corresponds to a wall-mounted heat pump (mini-split). This format is particularly popular in Montreal, Laval, and on the South Shore/North Shore because it allows for:

  • an installation without major ductwork work;

  • excellent room-by-room control (depending on the interior configuration);

  • interesting energy efficiency, especially in mid-season.


Visible installation details and important technical points

1) Installation on a gravel roof: stability and protection

In Ville-Marie, the roof is often the best location for the outdoor unit when:

  • The facades are regulated,

  • The balconies are too small.

  • or that one wants to minimize the visual impact.

Here, the unit is installed on a raised support , which offers several advantages:

  • better protection against the accumulation of water and debris;

  • reduction of risks related to snow and ice (depending on the roof configuration);

  • Improved clearance for air circulation.

2) Vibration management: comfort for occupants

Even a very good heat pump must be installed in a way that limits the transmission of vibrations. The photo shows decoupling elements (brackets/support points) between the unit and its mounting bracket. In a dense urban area like Ville-Marie, this is essential because:

  • to preserve the tranquility of the occupants,

  • to avoid resonances in the structure,

  • comply with the condominium requirements.

3) Insulated refrigeration connections: durability and performance

The pipes are well insulated (white sheath) and neatly routed. Adequate insulation:

  • improves efficiency (less heat loss),

  • limits condensation

  • protects pipes against premature wear.

4) Clearances and air circulation

One detail too often overlooked: the condenser needs to breathe. On a rooftop, we want:

  • sufficient clearance around the unit,

  • a logical approach to avoid "blowing" towards an obstruction,

  • and a configuration that facilitates maintenance (access to the panel, cleaning, service).

At AirGreen, we always plan the location so that the actual performance on the ground lives up to the advertised performance.


What this type of installation actually changes for the customer

Everyday comfort

With a Gree Charmo wall-mounted heat pump, the customer typically looks for:

  • a stable temperature (fewer variations);

  • quick comfort on very hot days;

  • efficient heating during transition periods (autumn/spring).

Discretion and integration into the building

Placing the outdoor unit on the roof helps to:

  • reduce the visual impact from the street;

  • free up living spaces (balcony/terrace);

  • limit noise complaints, especially in condominiums.

Simplified maintenance… when it's well thought out

A clean and accessible installation also saves time during maintenance:

  • seasonal cleaning of the outdoor unit;

  • checking the pressure and the condition of the fittings;

  • inspection of supports and level;

  • drainage control (depending on the configuration).


AirGreen's best practices for a sustainable installation in Montreal

Every construction site in Greater Montreal has its “pitfalls”: wind on roofs, freeze/thaw cycles, restricted access, condominium regulations, etc. For this type of installation, we systematically apply principles that make a real difference:

  • Robust and elevated support adapted to the surface (here, gravel roof).

  • Vibration reduction to protect acoustic comfort.

  • Clean, isolated and secure routing of the pipes.

  • Clearances respected to ensure good air circulation.

  • Aesthetic approach : discreet, clean, and professional.

It is often this level of finish that distinguishes a “correct” installation from a truly successful one, especially in an urban context like Ville-Marie.


Common mistakes to avoid (and that we often correct)

In central Montreal, we still see far too often:

  • units placed too low, exposed to stagnant water;

  • undersized supports (vibrations, instability);

  • a lack of clearance (overconsumption, wear);

  • poorly insulated pipes (condensation, losses, premature aging).

A high-performance heat pump like the Gree Charmo deserves a proper installation, otherwise some of the benefits are lost: comfort, efficiency, longevity.


Conclusion: a Gree Charmo perfectly suited to Ville-Marie

This installation in Ville-Marie illustrates exactly what many owners and co-owners in downtown Montreal are looking for: an efficient , discreet solution that is neatly integrated into the building.

With a Gree Charmo wall-mounted heat pump , installed on the roof with a raised support and careful execution, you get a system that meets urban requirements while offering concrete comfort, day after day, summer and winter.

Your numbers

The job tools

Two quick checks with real numbers: what heat costs, and what your current heaters add up to in BTU/h.

Size checkYour baseboards, in BTU/h
–BTU/h of installed electric heat

    Conversion: 1 W = 3.412 BTU/h. An indication, not a load calculation: baseboards and furnaces are often stronger than the real need, and they can stay as backup. AirGreen confirms the capacity on site.

    The steps

    How the job unfolds

    The main steps of this kind of job at AirGreen. Every house has its quirks: the estimate brings them out.

    Step 1 of 9The on-site estimate

    We look at the room, the outside wall, the line route and where the outdoor unit will go. That is where the capacity gets chosen.

    1. The on-site estimateWe look at the room, the outside wall, the line route and where the outdoor unit will go. That is where the capacity gets chosen.
    2. The quoteModel, capacity and price, in writing. We also check whether the model qualifies for assistance programs.
    3. Getting readyFloors and furniture protected, wall plate position marked level, wall opening located.
    4. The wall openingA single opening, with the slope the drain needs to flow outside.
    5. The outdoor unitSet on a stand raised above the snow, with the clearances the manufacturer requires.
    6. Lines, cable and drainConnected, insulated and protected. The opening is then sealed against water, cold air and insects.
    7. The electrical workA dedicated circuit and an accessible disconnect near the outdoor unit.
    8. Tests and start-upLeak test, vacuum, then start-up and a check of heating and cooling.
    9. The walkthroughRemote, modes, filters: we show you the essentials before we leave.
    The tour

    What we check on a job like this one

    Each number is a point we check on site. Switch between summer and winter to watch air and heat move.

    Generic diagram: wall-mounted heat pump, indoor and outdoor units

    In summer, the outdoor unit rejects the house's heat outside.

    Generic illustration of this type of installation, not a survey of this job site. Tap a number.

    1. Mounted level on a wall plate, high enough for the air to reach the whole room, with enough space around it to slide the filters out easily.

    2. The refrigerant lines, the communication cable and the drain go through the wall in a single opening, sealed against water, cold air and insects.

    3. Two insulated copper pipes connect the two units. Outside, a line cover can protect them from sun, knocks and weather.

    4. A shut-off switch near the outdoor unit isolates it safely for service. It must stay accessible at all times.

    5. The compressor and the fan. In heating mode it captures heat from the outdoor air, even in winter, and moves it inside.

    6. On the ground or on the wall, it keeps the unit above accumulated snow. The unit stays clear and defrost water can drain away.

    7. The fan needs to blow freely. Storage, a fence or a wall too close, and efficiency drops while noise goes up.

    At your place

    Is your home ready?

    Check what applies at your place. A "no" is not a refusal: it is what we sort out during the estimate.

    0 / 6 checked
    Maintenance

    Good habits, once the unit is in place

    Six simple habits that keep the unit going. Your list stays on this device.

    0 / 6 checked
    Through the seasons

    What to do, season by season

    Three habits per season for this unit. They take a few minutes and prevent many calls.

    • Clean the indoor unit's filters.
    • Clear leaves and debris left on the outdoor unit by winter.
    • Test cooling before the first hot days.
    For your project

    The right pages, at the right time

    True or false

    Four statements: true or false?

    It all comes down to details you have just seen.

    1. In heating mode, the outdoor unit can produce water.

    2. You pick the capacity with a simple square-footage rule.

    3. A multi-zone connects several indoor heads to a single condenser.

    4. The disconnect can sit behind the patio furniture.

    Frequently asked questions

    What people ask us about this kind of work

    12 questions
    Does a wall-mounted heat pump heat in winter?
    Yes, it heats and cools. Its capacity drops in very cold weather; the operating range depends on the model and is listed on its spec sheet.
    Wall-mounted or multi-zone: how do I choose?
    One wall head and one condenser outside: the direct solution for a room or an open area. For two to five rooms, a multi-zone puts one head in each room on a single condenser.
    Where does the outdoor unit go?
    Where it stays above the snow, clear and accessible, away from walkways. We decide it with you during the estimate.
    Are there grants?
    Depending on the model and your situation, assistance programs may apply, including Hydro-Québec's LogisVert. AirGreen checks the model number before quoting an amount. See the grants.
    Do I need a permit?
    Rules vary from city to city: location, distances, noise. See permits and by-laws, and we check for your address.
    How cold can it heat?
    It depends on the model. According to Hydro-Québec, newer models work down to a temperature between −15 °C and −25 °C, and some cold-climate models are certified lower. The minimum temperature is on each unit's spec sheet.
    How much can I save?
    Hydro-Québec says a heat pump can be up to three times more efficient than baseboards for heating in the colder months. The result depends on the house, the climate and how it is used.
    How is the LogisVert assistance calculated?
    For ENERGY STAR cold-climate certified heat pumps, Hydro-Québec lists assistance of $120 per 1,000 BTU/h of heating capacity at −8 °C. AirGreen checks the exact model before quoting an amount; only Hydro-Québec confirms the assistance granted. See the grants.
    Is it noisy?
    The sound level depends on the model and is listed in decibels on each unit's spec sheet. Location matters too: when possible, we avoid putting the outdoor unit under a bedroom window.
    The outdoor unit is covered in ice: is that normal?
    Some frost is: the unit runs defrost cycles. Never hit the ice. If the unit stays iced up or stops heating, call us.
    Does AirGreen hold the required licences?
    Yes. AirGreen holds RBQ licence 5645-9605-01, subclasses 15.8 Ventilation, 15.10 Refrigeration and 16 Electricity.
    Is the estimate free?
    Yes. The on-site estimate is free and the quote follows within 24 hours. Book my free estimate.

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    An on-site estimate, the right capacity, the right equipment.

    The on-site estimate is free and the quote follows within 24 hours.

    • RBQ licence5645-9605-01 · 15.8, 15.10, 16
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    Text and photo: a real AirGreen Climatisation & Chauffage job. The diagrams are generic illustrations of the type of installation, not a survey of this job site. Sources of the added figures: airgreen.ca product pages (NEEP / AHRI performance), Hydro-Québec (Heat pumps page, LogisVert, read on 13 October 2026), Régie de l’énergie (rate D as of 1 April 2026).

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