Installation of a Samsung Premium FJM dual-zone heat pump in Sainte-Marthe-sur-le-Lac

A multi-zone solution integrated into a roof-level space undergoing renovation

Installing a Samsung Premium FJM dual-zone heat pump in Sainte-Marthe-sur-le-Lac in a completed home is a relatively standard project. However, carrying out the same installation in a roof-level space undergoing renovation requires much more precise planning.

On this project, one of the wall-mounted indoor units had to be positioned in a room built directly beneath the roof slopes. The visible environment during the work presented several distinctive features: exposed wood framing, a sloped ceiling, spray-foam insulation, existing beams, ducts crossing the space, and finish surfaces that were still open. These conditions gave us access to the structure, but they also required us to make the right decisions before permanently closing the walls and ceiling.

Our goal was not simply to mount a Samsung unit on the wall. We had to create a clean, accessible, and durable HVAC installation, while planning for the passage of refrigerant lines, communication wiring, and the condensate drain inside a complex architectural layout.

Why a dual-zone heat pump was suitable for this property

A dual-zone heat pump, also called a multi-zone ductless split system, makes it possible to connect two indoor units to a single compatible outdoor unit. Each indoor unit serves a distinct area of the home and generally has its own temperature control.

This configuration was particularly relevant for this Sainte-Marthe-sur-le-Lac residence, since comfort needs were not identical throughout the building. A room located beneath the roof can accumulate more heat in summer, even when the rest of the house remains relatively comfortable. In winter, its thermal behavior depends in particular on:

• of the quality of the insulation beneath the roof;
• of airtightness;
• of sun exposure;
• of the window area;
• of the ceiling’s height and shape;
• of the natural circulation of air between floors.

With a Samsung Premium FJM dual-zone configuration, occupants can adjust the temperature of each space more precisely rather than forcing a single unit to handle areas with different thermal loads.

An indoor unit installed on a partition designed to receive the finishing

The site photograph clearly shows one of the wall-mounted indoor units installed on a section of drywall while the finishing work was still underway. This work sequence was important.

When we work during a renovation, we can coordinate the routing of the lines before all the surfaces are closed. This often reduces the amount of exposed line-hide and results in a more discreet appearance. However, this method requires close communication with the contractor, carpenter, or owner to prevent the lines from being damaged by a screw, nail, or subsequent framing modification.

The unit’s support had to be rigid enough to prevent movement and vibration. An indoor unit must not be installed on an unstable surface or on an inadequately supported finishing panel. We therefore check the location of the studs, the wall’s flatness, and the available space behind the mounting plate.

The positioning also had to allow for:

• unobstructed air distribution toward the occupied area;
• future access to the filters;
• full opening of the front panel;
• access for servicing the heat exchanger and fan;
• an adequate drain slope;
• a reasonable distance from the finished ceiling;
• no obstruction in front of the air discharge louvers.

The particular challenge of a sloped ceiling

In a conventional room, the horizontal ceiling generally provides a simple reference point for positioning a wall-mounted air conditioner or heat pump. Under a sloped roof, every centimetre matters more.

The Samsung unit had to be installed high enough to promote good air distribution, but not so high that servicing it after the ceiling was closed would be compromised. The thickness of the finishing materials that would be added around the unit also had to be anticipated.

A common mistake is to position the unit according to the rough structure without considering the finished ceiling. After drywall, trim, or other coverings are installed, the space required to remove the filters may become insufficient. In the most problematic cases, the unit panel can no longer open properly.

On this installation in Sainte-Marthe-sur-le-Lac, we therefore assessed the finished environment rather than limiting ourselves to the temporary appearance of the construction site.

Spray foam insulation: an advantage that requires certain precautions

The visible insulation between the framing members is spray foam. This type of insulation can help improve the building envelope’s airtightness when applied continuously and correctly. For a room located under the roof, this improvement can reduce air infiltration and limit summer heat gain.

For the HVAC installer, however, spray foam requires special attention. Refrigerant lines and wiring must not be placed randomly in the cavities. We must plan for their accessibility, mechanical protection, and position in relation to future work.

It is also essential not to crush the insulation surrounding the copper pipes. Damaged or discontinuous insulation on the refrigerant line can cause condensation, especially during cooling operation. In an enclosed cavity, this moisture may go unnoticed for a long time.

Managing condensate drainage in an attic room

When a heat pump operates in cooling mode, the indoor unit removes moisture from the air. This water must be discharged through a properly installed drain.

In an attic space, routing the drain can be one of the most challenging aspects of the project. The pipe must maintain a constant downward slope when drainage relies on gravity. Backslopes, unnecessary rises, and sagging sections can cause water to accumulate, gurgling noises, or the condensate pan to overflow.

During this installation, we took advantage of access to the structure to plan the routing before the surfaces were closed. Depending on the building’s design, the drain can be directed outside or toward a suitable drainage point. When a natural slope is not possible, a condensate pump may be considered, but we favor gravity drainage whenever the configuration allows it. An installation without a pump reduces noise, maintenance, and the number of mechanical components that may require service.

Preparation of refrigerant lines and wiring

The Samsung Premium FJM system relies on coordinated communication between the outdoor unit and the indoor units. Each branch must be connected in accordance with the manufacturer’s requirements, using lines suited to the installed equipment combination.

During our multi-zone heat pump installations in Montréal, Laval, Longueuil, on the North Shore and on the South Shore, we pay particular attention to the following:

• exact diameter of the refrigerant lines;
• total system length;
• height differences between the units;
• quality of the flares;
• tightening torque of the connections;
• complete insulation of the lines;
• protection against rubbing against the structure;
• pressure leak test;
• vacuum evacuation before commissioning;
• clear identification of each circuit.

In a dual-zone system, an identification error between the wiring and the lines can cause the units to be mismatched. For example, a command sent by one indoor unit could be associated with the wrong refrigerant circuit. Checking each branch is therefore an integral part of commissioning.

This project illustrates the importance of planning the HVAC system before closing the walls.

Two zones do not mean two completely independent systems

A dual-zone heat pump allows the indoor units to be adjusted separately, but both zones share the same outdoor unit. It is important to explain this distinction to homeowners.

The indoor units may require different temperatures, but they generally need to operate in compatible modes. One zone normally cannot provide heating while the other simultaneously requires cooling. The outdoor unit responds to the requests according to the system’s operating logic and the load of each space.

This characteristic is not a defect; it is part of the normal operation of a residential multi-zone system. This setup is particularly well suited when the served zones are used under similar seasonal conditions, such as two bedrooms, an upper floor and a living area, or an attic room and another section of the house.

Air distribution suited to the room’s geometry

In this installation, the wall-mounted unit was positioned to direct air into the main volume of the room rather than directly against a beam or into a ceiling cavity. The presence of a sloped roof can alter the natural movement of warm and cool air.

In cooling mode, cool air gradually descends. A unit installed high enough can therefore effectively cover the occupied area as long as its airflow remains unobstructed. In heating mode, the louver orientation should promote airflow downward to prevent warm air from accumulating near the roof.

The positioning of the unit often plays as important a role as its rated capacity. An oversized unit in the wrong location can provide less uniform comfort than a properly selected and strategically placed unit.

Mistakes to avoid during a similar renovation

Installing a heat pump during construction creates interesting opportunities, but it also exposes the system to certain risks. Here are the mistakes we seek to prevent:

Closing the wall before confirming all routes

A line trapped behind a finish with no access or protection can complicate future repairs. The routes must be verified before closing the wall.

Installing the unit too close to the finished ceiling

The space required to open the panel, remove the filters, and clean the unit must be preserved after the finishing materials are added.

Drilling near concealed lines

The contractors finishing the wall must know the location of the pipes, drains, and wires. Photographs taken before closing the wall can be very useful.

Neglecting the drain slope

A drain that appears acceptable over a short section can develop a reverse slope when it passes through several framing members. The entire route must be checked.

Blocking the return or supply air

A decorative beam, cabinet, or partition added after installation can restrict airflow and reduce the unit’s performance.

Turning on the unit during very dusty work

Drywall dust and construction debris can quickly clog the filters, coil, and blower wheel. When work is still underway, the unit must be protected and its use controlled.

Commissioning is not limited to turning on the heat pump

After the connections are made, we perform a series of checks before considering the installation complete. This step may include checking pressures according to the applicable procedures, verifying supply and return air temperatures, testing the drain, listening for vibrations, and validating the controls for each zone.

We also check:

• the stability of the indoor unit;
• louver opening;
• fan operation;
• communication between the units;
• the absence of error codes;
• the operation of each zone;
• the cleanliness of the connections;
• accessibility for HVAC maintenance.

In a building under renovation, an additional final inspection may be necessary after the ceiling, drywall, and moldings have been installed. It confirms that no material has been placed too close to the unit and that the lines have not been moved or damaged.

Recommended maintenance to preserve system performance

A Samsung wall-mounted heat pump must remain clean to maintain adequate airflow. The occupant can clean the filters periodically, but more thorough maintenance becomes necessary when dust accumulates on the heat exchanger, blower wheel, or condensate pan.

In a recently renovated room, we recommend particular vigilance during the first few months. Even after the worksite has been cleaned, fine particles may remain in the air and reach the unit.

Professional maintenance may include:

• cleaning the heat exchanger;
• cleaning the blower wheel;
• inspecting the pan;
• checking the drain;
• examining the connections;
• checking the outdoor unit;
• evaluating airflow;
• checking for unusual noises or vibrations.

An installation designed for future finishing, not just for the day’s work

This Samsung Premium FJM dual-zone heat pump project in Sainte-Marthe-sur-le-Lac shows why a successful installation begins well before startup. In an attic space, we must consider the structure, insulation, slopes, future finishing surfaces, water drainage, and airflow as a whole.

The goal is a system that appears naturally integrated once the work is complete. The lines should be discreet, the unit should remain accessible, and the airflow should effectively cover the room without interfering with architectural elements.

At AirGreen, we install multi-zone and dual-zone heat pumps in Sainte-Marthe-sur-le-Lac and throughout Greater Montreal, including Laval, Longueuil, Montreal, the North Shore, and the South Shore. Each project is planned according to the actual building, rather than a theoretical configuration replicated from one home to another.