Installation of a Sharp ZU1 wall-mounted heat pump in Le Sud-Ouest (Montreal)

Condenser on flat roof: a robust, clean and guaranteed membrane installation

At AirGreen , we adapt our HVAC installation methods to Montreal's architecture. In this project located in Le Sud-Ouest , we are installing the condenser of a Sharp ZU1 wall-mounted heat pump on a flat roof with an elastomeric membrane. The goal: to ensure reliable operation all year round, preserve the integrity of the roof and facilitate future maintenance, all with impeccable aesthetics from the street and from the terrace.

Building context and technical choices

The building is a recent multiplex with a reflective white roof. The client wanted:

• a quiet, high-efficiency wall-mounted heat pump to cool and heat the main living area;

• an exterior installation on the roof to free up the facades and reduce sound transmission to neighbors;

• a solution that respects the roof warranty and the rules of the co-ownership association.

The Sharp ZU1 , R-32 generation, meets the requirements perfectly: high seasonal efficiency, very good performance in cold weather, nighttime silent mode, and compatibility with Quebec grant programs for efficient heat pumps . Inside, the wall-mounted head (installed high up) provides a regular airflow; outside, the condenser is positioned in an unobstructed area of ​​the roof.

Roof support: stability without drilling

To protect the membrane, we designed a load path made of treated wood (sole plates) receiving an aluminum support . This configuration:

• distributes the weight of the condenser over a large surface area;

• avoids any piercing of the membrane (no mechanical anchoring);

• incorporates anti-vibration pads under the feet to reduce sound transmission and protect the finish;

• Leaves clearance under the unit for drainage, maintenance and snow blowing.

The supports are aligned with the roof slopes so as not to hinder drainage . The whole is leveled to ensure optimal operation of the compressor and the refrigeration circuit.

Crossing management: waterproofing and durability

The refrigerant connections , the power cable and the condensation drain are grouped together in a dedicated flashing box . Inside this box:

• we produce a pitch-pocket/chem-curb type seal compatible with the elastomer;

• the cables are UV sheathed and fixed to avoid friction on edges;

• a service lace (loop) absorbs thermal expansion and facilitates possible maintenance.

Externally, the capping follows a short and logical path to the inner head, limiting pressure losses. The total copper length remains within the manufacturer's parameters , with deep vacuum , nitrogen evacuation during soldering and documented leak testing .

Respect clearances and wind

A rooftop condenser is more exposed to wind and sunlight . We therefore apply:

• clear rear and side clearances for airflow (in accordance with Sharp guidelines);

• free height above the unit to avoid recirculation under gusts;

• remote positioning of parapet upstands and ventilation caps so that exhaust air is not taken back in;

• orientation which avoids the accumulation of snow carried by the wind; if necessary, installation ready to receive a snow guard .

These precautions reduce frost formation in winter, improve performance and extend component life.

Electrical Safety and Future Service

An accessible external disconnect switch is provided according to the Code, with wiring calibrated to the maximum current of the unit. Technician access is thought out today: clear surface around the support, stainless steel screws , and working height that allows the service panel to be opened without removal. This care simplifies HVAC maintenance and reduces lifecycle costs.

Key steps of our method (operational summary)

1. Roof survey : slopes, drains, obstacles, access, shaded/snow areas.

2. Installation of the loading path in treated wood and aluminum support with pads.

3. Condenser installation and precise leveling .

4. Crimping/soldering of copper lines with nitrogen flushing .

5. Vacuum draw (controlled microns) and pressure test .

6. Electrical connection with disconnect switch and clear marking.

7. Waterproof finish of the crossings in the flashing box.

8. Start-up , refrigeration measurements (superheat/subcooling), checking intensities and modes .

9. Customer discount : seasonal usage tips and maintenance schedule.

Why this setup works in Montreal

• Climate : Windy winters on flat roofs require rigid support, stable foundations , and clearances above the minimums. We respect them.

• Urban acoustics : the roof mass and elevation lower the noise impact on the neighborhood, while keeping the machine out of traffic areas.

• Aesthetics : no projection on the facade; the unit remains invisible from the street and does not harm the built heritage.

• Maintenance : direct access from the hatch or roof stairs; components installed to be serviceable without moving the condenser.

Result: comfort, efficiency and serenity

The owner benefits from stable comfort in both summer and winter, a measurable reduction in consumption thanks to the inverter, and a clean and durable outdoor installation. The Sharp ZU1 ensures reliable operation in cold weather, and the entire project is calibrated to meet the criteria of the subsidies available in Montreal, Laval, Longueuil, North Shore and South Shore when applicable to extreme cold heat pumps .

AirGreen Tips for a Flat Roof Condenser

• Choose a support without membrane piercing and document the materials used.

• Provide short line routing and quality UV insulation .

• Anticipating the wind : orientation, clearances, and anti-displacement devices.

• Keep a clear perimeter for maintenance and airflow.

• Schedule annual maintenance : coil cleaning, electrical tightening, pressure and condensate checks.

Our projects in the South West, Plateau, Rosemont, Villeray and elsewhere demonstrate that a well-thought-out roof installation is a reliable , silent and roof-friendly solution.

AirGreen: local HVAC expertise, from quotes to grants

We support our clients from sizing to commissioning , with test reports, installation photos and assistance with grant applications . Are you planning a wall-mounted heat pump in Montreal , Laval , Longueuil , on the North Shore or the South Shore ? Our teams offer an HVAC installation adapted to the building, the climate and the budget, favoring recent high-efficiency R-32 models.