Installation of a Gree (R-32 series) wall-mounted heat pump in Villeray–Saint-Michel–Parc-Extension

A flat roof installation designed for the Montreal climate and the longevity of the equipment

Client background and objectives

At AirGreen , we were approached by the owner of a plex in the Villeray–Saint-Michel–Parc-Extension neighborhood of Montreal . The need was clear: modernize summer comfort, reduce energy bills in the spring and fall, and have reliable backup heating in the winter, without transforming the interior. We recommended and installed a new-generation Gree wall-mounted heat pump with R-32 refrigerant , sized for an open main living area. The configuration chosen favored an outdoor installation on a flat roof —a common solution in Montreal plexes—to free up the facades and preserve the aesthetics of the backyard.

Why a Gree R-32 heat pump in this case?

• Improved Seasonal Efficiency : Gree R-32 platforms achieve very good SEER/HSPF, with a lower refrigerant charge than R-410A technologies.

• Cold weather performance : stable operation announced down to -25°C , or even -30°C depending on the range; an asset for our winters.

• Silence and even diffusion : the interior head ensures gentle blowing and precise motorized shutters , comfortable for teleworking.

• Potential eligibility for programs when Energy Star and “extreme cold” performance thresholds are met — we verify compliance for Montreal, Laval, Longueuil, North Shore, South Shore .

Reading the frame and sizing

We size the capacity based on insulation, orientation, internal inputs and floor plan:

• 9,000 to 12,000 BTU : rooms or living spaces up to ~40 m² with proper insulation.

• 18,000 BTU : Larger areas, high ceilings, or prolonged direct sunlight.

• If there are several distinct zones, a MultiZone heat pump can be considered; here, a wall-mounted head is sufficient to achieve the comfort objective.

Installation details – exterior installation on flat roof

Our intervention focuses on the mechanical reliability and integrity of the roof:

• Support : condenser placed on a galvanized frame mounted on treated wooden soles/sleepers and anti-vibration mats to distribute the loads on the gravel and protect the membrane .

• Refrigeration connections : short and direct route from the inner head, continuous UV-resistant insulation, ducts closed with sealing tape; large radius bends to preserve the copper.

• Electrical : Regulatory proximity disconnect box , protected flexible whip , rating and circuit breaker as per Gree nameplate; verified earthing.

• Roof waterproofing : penetrations made in a roof passage with elastomeric mastic /sleeve, positive slope ensured to avoid water retention.

• Defrost condensate management : free evacuation in winter, clear area so that ice does not rise in the device; if the architecture requires it, deflectors or defrost tray can be added.

• Accessibility : clearances respected all around for maintenance, clear service flap , rear grille releasing the suction.

• Wind protection : orientation of the condenser with its back to the prevailing winds and tightening of the anchors to prevent movement in gusts.

Result: a refrigeration path estimated between 3 and 6 m , without unnecessary pressure losses, which improves performance and limits fluid noise.

Key technical steps

1. Preparation : protection of traffic areas, verification of roof supports, laser survey of anchor axes.

2. Drilling : slightly outwardly sloping hole for a secure gravity drain ; watertight bulkhead.

3. Fixing the inner head plate and hanging it, checking the level and free operation of the shutters.

4. Controlled flaring (flare gauge), dynamo nuts on expanders to guarantee durability over time.

5. Nitrogen leak test and deep vacuum (< 500 microns), then stabilization and penetrant testing.

6. Commissioning : checking intensities, supply/return air temperatures, pressures, and correction of parameters (mode, dehumidification, auto speed).

7. Delivery to the customer : instructions for use, good HVAC maintenance practices, maintenance schedule.

Advantages of installing on a flat roof in Montreal plexes

• Zero visual impact on the courtyard and the facade.

• Less noise perceived by neighbors and occupants.

• Optimized clearances for interventions.

• Reduced risk of vandalism or obstruction by vegetation.

Points of vigilance managed by our team: compliance with the permissible loads of the roof, routes outside areas of water stagnation , and sufficient natural de-icing around the unit in winter.

Comfort and performance observed

• In cooling mode, the target temperature is reached quickly, with better controlled humidity thanks to Dry mode when the air is heavy.

• During the off-season, the heat pump covers most of the needs, reducing the call on the main system.

• In winter, the Gree range's " extreme cold " strategy maintains useful power, with short and well-managed defrost cycles.

Best practices for maximizing energy savings

• Stable setpoint (e.g. 23–24°C in summer) to avoid short cycles.

• Auto fan speed in cruising mode; vertical sweep for even diffusion.

• Interior doors open to allow air circulation to adjacent rooms.

• Programming during off-peak hours when relevant.

• In winter, keep the outdoor unit clear of snow and ice.

HVAC Maintenance – Recommended Schedule

• Filters : Rinse every 4–8 weeks during heavy use.

• Internal battery : annual cleaning and gentle disinfection to maintain thermal exchange.

• Condenser : cleaning of the fins in spring, checking of the protective grille and straightening of the fins if necessary.

• Annual inspection by AirGreen: pressures, currents, line insulation, fluid load, sensor operation and roof penetration sealing .

Common Pitfalls…and How We Avoid Them

• UV-exposed chutes that degrade: We use UV-stabilized materials and quality waterproof tape.

• Poorly thought-out drainage : our drilling is on a slope , and we control the evacuation to the outside to remain gravity-based .

• Vibrations transmitted to the building: silent blocks and tightening torques respected, plus a hot check at the end of commissioning.

• Approximate roof penetration : waterproof roof pass-through and membrane-compatible mastic, with photos of the work provided to the customer.

Technical data sheet summarizing the installation

• Type : single-zone wall-mounted heat pump .

• Brand : Gree , new R-32 platform .

• Typical installed capacity : 12,000 or 18,000 BTU (depending on thermal balance).

• Outdoor installation : flat roof on galvanized frame, anti-vibration bases.

• Cooling path : ~3–6 m, continuous UV insulation.

• Electricity : Dedicated 208–230 V circuit, disconnect box within reach.

• Maintenance : filter 4–8 weeks, annual AirGreen inspection.

• Areas served : Montreal, Laval, Longueuil, North Shore, South Shore .

Why AirGreen for your HVAC system?

We combine sizing engineering , careful execution and structured after-sales service . Our team understands the constraints of Montreal plexes and roofs, ensures a durable HVAC installation and supports you in optimization, HVAC maintenance and the study of eligibility for subsidies when the configuration allows it.

Are you looking for a heat pump that's as discreet as it is efficient for your building in Montreal or the surrounding area? We handle the technical inspection, thermal assessment , flat roof installation, and certified commissioning , with careful monitoring season after season.