Careful HVAC modernization in a Rosemont plex: four-season comfort, low noise, preserved aesthetics
Client context and objectives
At AirGreen , we are working in a typical Rosemont–La Petite-Patrie plex . The client occupies a 4 1/2 facing southwest, very sunny in the afternoon and often overheated in the summer, but cool in the morning in mid-season. His priorities: stable comfort , very low noise levels , controlled consumption and discreet integration that respects the existing moldings and openings. We selected a Midea wall-mounted heat pump, model from the Midea28 range with R-454B refrigerant , a recent solution designed for the Quebec climate and compatible with Quebec grant programs when the efficiency criteria are met.
Why a Midea28 wall-mounted heat pump in this specific case?
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Heating/air conditioning versatility : a single unit covers summer cooling and winter supplementary heating , ideal for urban housing where technical space is limited.
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New generation refrigerant (R-454B) : high efficiency and reduced environmental footprint compared to older generations.
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Quiet operation : the indoor head is renowned for its very low speeds, which are pleasant in the evening.
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Aesthetics : discreet casing, minimal exposed HVAC installation , rear passage to the outside to hide the piping in the living areas.
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Eligibility for aid (depending on configuration and performance): possibility of benefiting from active programs in Quebec (Hydro-Québec LogisVert , Rénoclimat ), useful for projects in Montreal , Laval , Longueuil , on the North Shore and the South Shore .
Our approach to HVAC installation in a Montreal plex
Location and sizing (BTU)
We validate the thermal loads room by room: surface area, ceiling height, solar gain, insulation of the wall facing the alley and frequency of occupancy. For an open living room with an adjoining kitchen, we favor a power of around 12,000 BTU (to be adjusted according to the envelope). The objective: to avoid oversizing (short cycles, poorly managed humidity) as well as undersizing (inefficient continuous draft).
Choice of location of the inner head
The photo shows the head installed in a high sill above the window , an ideal orientation for sweeping the air along the ceiling and taking advantage of the Coandă effect . Advantages:
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Even diffusion in the living area.
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Minimized nuisance : no direct blowing on the sofa or table.
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Short refrigeration path : the wall opens directly onto the outside, limiting losses and optimizing efficiency .
Wall crossing and path
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Carefully drilled Ø 65 mm with outward slope for gravity drainage of condensate.
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Sheath and vapor barrier for airtightness.
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Insulated refrigeration piping (copper supply/return) passing directly behind the unit: total length < 3 m , reducing pressure losses.
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Gravity condensate drain : no visible pump or additional noise; the drain is protected against frost and splashing onto the lower balcony.
Power supply and protections
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Dedicated circuit for the panel (208/230 V depending on the size chosen), circuit breaker and disconnect outside for safe maintenance.
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Inside, the ceiling-molded cable follows the moldings to remain discreet and preserve the aesthetics. Our master electrician checks the polarities, grounding, and currents according to the nameplate of the selected Midea28.
Installation of the outdoor condenser
In an urban complex, we avoid taking up floor space. We generally install the condenser on galvanized wall brackets on the courtyard/alley side:
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Clearances respected (free suction and blowing).
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Snow-free height and anti-vibration mats for low noise transmitted to the structure.
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Defrost water management : drip tray and safe routing to prevent ice on the balcony.
Rigorous commissioning
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Leak test with high pressure nitrogen , then deep vacuum until stabilization.
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Opening of the valves , weighing of the additional fluid if necessary according to the actual length.
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Functional checks : ΔT in cold/heat, intensities, fan speed , communication and thermistor .
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Comfort settings : auto tempered mode, vertical sweep , eco setting at night.
Observed results and concrete benefits for the occupant
Thermal comfort and humidity
The diffusion above the window stabilizes the temperature. In summer, the room remains in the 22–24 °C range with gentle dehumidification ; in winter, the Midea28 provides effective additional heating down to the low temperatures provided by the range, complementing the existing main heating.
Silence and air quality
The low speed of the indoor head is almost imperceptible on quiet evenings. Washable filters trap dust and pollen; biannual HVAC maintenance keeps the exchanger efficient and clean.
Energy sobriety
The combination of short refrigeration length , R-454B refrigerant and inverter electronics limits consumption. The customer notices a significant reduction in summer kWh compared to an old window air conditioner, while gaining the benefit of additional heating between seasons.
Technical details and AirGreen best practices
Finish and aesthetics
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White UV exterior capping matching the brick/facing for a sober facade.
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Controlled drain slope (3–5 mm/m): quiet drainage without gurgling.
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Rodent/insect protection : discreet mesh at the drain outlet.
Recommended HVAC maintenance
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Filter cleaning : every 4–6 weeks in summer.
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Chemical washing of the evaporator and annual light biocide treatment.
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Condenser clearance : 30 cm around free of leaves/snow.
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Electrical inspection : terminal tightening, insulation test, operating current measurement.
Tips for maximizing savings
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Maintain a stable temperature (23°C in summer; 20–21°C in mid-season).
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Use dehumidification mode during humid episodes rather than lowering the setpoint excessively.
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Program the auto speed in the evening for optimal acoustic comfort.
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Keep interior doors ajar to even out the temperature in a 4 1/2.
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Schedule maintenance in the spring before the heatwave and another in the fall before the frost.
Construction site challenges and solutions implemented
Constraint 1: Heritage and moldings
The high moldings and period woodwork require careful routing. We aligned the head with the lintel, ran the electrical molding through the ceiling , and drilled outside the joints to preserve the structure, without any unsightly visible returns.
Constraint 2: Backyard and neighborhood
Close proximity requires attention to outside noise . Installation on brackets with silent blocks and sufficient clearance limits resonance on the brick. The direction of the blowing avoids any disturbance towards the neighboring balcony.
Grants and eligibility (Montreal, Laval, Longueuil, North Shore, South Shore)
Depending on the configuration chosen in the Midea28 range (efficiency and operating temperature), the installation may be eligible for certain Quebec programs: Hydro-Québec – LogisVert for efficient heat pumps and Rénoclimat if an energy evaluation process is undertaken. We support our clients to verify the criteria , prepare the files and optimize the overall budget of the project.
What AirGreen changes for your project
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Local engineering : precise sizing, respect for Montreal buildings.
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Quality of execution : certified refrigeration engineers, vacuum to 500 microns and systematic pressure tests .
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Clear warranty and local after-sales service .
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Personalized usage tips to extend lifespan and reduce bills .
Next step
Are you planning a similar HVAC installation in Montreal , Laval , Longueuil , on the North Shore or South Shore ? We evaluate your home, suggest the right BTU output and deliver a clean, durable and quiet installation – in the spirit of this project in Rosemont–La Petite-Patrie .