Installation of a MIDEA EVOX G3 horizontal electric furnace in an attic in Terrebonne

In Terrebonne, the attic framing dictated the entire geometry of this MIDEA EVOX G3 installation

This installation carried out by AirGreen in Terrebonne illustrates a very practical aspect of the HVAC technician’s trade: sometimes, the main challenge is not deciding where to place the equipment in a large mechanical room, but successfully integrating a complete central system between the structural elements of an existing attic, without compromising airflow, drainage, or future access to the components.

The photograph taken during the work is particularly revealing. The MIDEA EVOX G3 electric furnace is installed horizontally beneath the roof, surrounded by a wooden frame that leaves very little room to maneuver. A vertical stud is located directly in front of the work area, and our technician must literally work around it to complete the connections and checks.

We can also see a large metal protective pan, particularly relevant in an attic, as well as the ducts and connections located at one end of the unit. The configuration is compact, but the main panels and technical access points must still remain sufficiently accessible to allow installation, commissioning, and eventuallyHVAC maintenance.

Midea presents the EVOX G3 as a central ducted system, designed specifically to facilitate the modernization of residential heating.

A horizontal installation that avoids working against the structure of the house

In an open basement, a central electric furnace is frequently installed vertically. In Terrebonne, this orientation would have been much less practical.

The available height decreases rapidly beneath the roof slope, while the structural timbers occupy a significant portion of the space. We therefore used a horizontal configuration that allowed the EVOX G3 to follow the geometry of the attic.

This capability is one of the platform’s most useful features. Midea provides several orientations: upflow, downflow, left horizontal, right horizontal, and low-boy configurations, for a total of six installation options presented in the documentation.

On a project like this, that versatility is not merely a convenience. It can avoid much more extensive modifications to the ductwork or the building structure.

A modular design particularly suited to difficult-to-access spaces

Before connecting a machine in an attic or crawl space, it must first be transported there.

This is a detail that homeowners rarely consider when comparing two central systems. Yet a heavy one-piece unit can become extremely difficult to move when access is through a small opening and it is then necessary to maneuver around beams, rafters, and ducts.

The EVOX G3 design uses a modular assembly that Midea describes as Block N Lock. The manufacturer specifically points out that this architecture facilitates transporting the units into complex spaces such as attics and basements, while allowing several configurations once the equipment reaches its destination.

In Terrebonne, this design philosophy is directly relevant: the photo shows a space in which every movement must be planned around the framing.

The technician must still be able to work once the unit is in place

A common mistake is to check only whether the machine can physically fit into the space.

For us, that is not enough.

A professional HVAC installation must also allow us to:

• remove the necessary panels;
• reach the electrical components;
• access the fan;
• check the coil;
• inspect the refrigerant lines;
• service the drainage;
• replace a filter;
• carry out a diagnosis several years after installation.

The Terrebonne photo makes this problem immediately clear. The unit passes through the attic, but a major structural component is located in front of the service area. Our positioning therefore had to account for this constraint from the outset.

It is much easier to plan for these clearances during installation than to discover, during a breakdown several years later, that a component cannot be removed.

The metal pan beneath the unit: a particularly important detail in an attic

Under the MIDEA EVOX G3, we can clearly see a large metal surface forming protection beneath the unit.

In an installation located above living spaces, condensate water management deserves particular attention.

When the system operates in cooling mode, the indoor coil becomes cold. Moisture in the air condenses on it and must be drained properly.

In a basement, a small leak is sometimes noticed quickly on a concrete floor. In an attic, a leak can reach:

• insulation;
• wood;
• ceiling materials;
• the finishes of the rooms below.

We therefore address the the condensate drain, its route, and the protection beneath the equipment as essential elements of the project, not accessories to be addressed at the end of the installation.

An “electric furnace” that works with a central heat pump

The term MIDEA EVOX G3 electric furnace which corresponds to how many Quebec homeowners refer to their central indoor unit.

Technically, the unit is part of a central air handler system that can be paired with a variable-speed heat pump and auxiliary electric heating.

The operating logic is important.

For much of the winter, the heat pump can produce the heat the home needs. Electric heating can then provide supplemental heat when demand exceeds what the heat pump can provide on its own or when the control strategy calls for backup.

Midea provides auxiliary heating modules that can deliver up to 25 kW, with adjustment and staged activation options depending on the configuration.

However, the availability of a 25 kW element never means that every home should receive 25 kW.

At AirGreen, we must consider the building’s heating load, the heat pump’s capacity, the available electrical supply, and the required protections.

Heating down to -30°C: why this feature matters in Terrebonne

A central heat pump in Quebec must be evaluated based on its performance under actual winter conditions.

The EVOX G3 documentation indicates continuous operation down to -30°C. Midea also indicates, based on its system testing, a capacity that can reach 100% around -25°C, with a COP that can reach approximately 1.9 under these conditions.

COP is particularly useful for understanding how a heat pump works. A COP above 1 means that the system provides more thermal energy than the amount of electricity directly consumed by its refrigeration cycle.

That is precisely what distinguishes heat pump heating from purely resistive heating.

In a residence in Terrebonne or elsewhere on the North Shore, so the objective is to operate the heat pump efficiently while maintaining the electric backup required during peak conditions.

What BTU capacity was installed here?

We might be tempted to estimate this EVOX G3’s capacity from the dimensions of its cabinet. That would not be sufficiently accurate.

The technical plate is visible in the photograph, but it is partially obscured by the technician’s position and a structural element. The full model number cannot be read with sufficient certainty to assign a precise tonnage to this installation.

Midea documentation lists several EVOX G3 sizes, including 18,000, 24,000, 30,000, 36,000, 48,000, and 54,000 BTU/h, depending on the indoor and outdoor unit combination.

For a homeowner, this distinction is important: the right capacity is not simply “the largest one that fits in the attic.”

We consider, among other factors:

• the home’s heat loss;
• the floor area;
• the insulation;
• the fenestration;
• the building’s exposure;
• the duct system’s capacity;
• the required airflow;
• the heating capacity required in very cold weather.

Variable efficiency depending on the exact combination

Depending on the combinations listed by Midea, the EVOX G3 platform achieves performance levels ranging up to 19 SEER2, 12.5 EER2, 10.8 HSPF2 and a COP at -15 °C of up to 2.14.

However, these values are range maximums.

The technical table shows that performance varies among capacities. The 18,000, 24,000, 30,000, 36,000, 48,000, and 54,000 BTU/h models do not all have exactly the same SEER2 or HSPF2.

Therefore, we must always use the exact combination indoor unit + outdoor unit to determine official performance.

This Terrebonne project reminds us that airflow and maintenance matter just as much as the specification sheet

In a central system, the furnace never works alone

A new MIDEA EVOX G3 may have an excellent blower motor, but the air still has to circulate through an entire duct system.

In a central system, we must examine:

1. the return air;
2. the filter;
3. the coil;
4. the fan;
5. metal transitions;
6. main ducts;
7. branch ducts;
8. supply grilles.

Each restriction increases the pressure the fan must overcome.

Poor performance attributed to the “heat pump” can sometimes result from an overly restrictive filter, undersized ductwork, or poorly balanced distribution.

Computational Constant Airflow 2.0: an interesting technology for renovations

The EVOX G3 uses what Midea calls Computational Constant Airflow 2.0.

According to the manufacturer, this technology allows the system to adjust the motor’s power and speed to better maintain airflow despite changes in resistance throughout the duct system. The documentation indicates a capacity of up to 1.2 in. of static pressure under the stated conditions.

Midea also provides up to 60 airflow adjustment levels.

This flexibility becomes particularly interesting when we install a modern unit on an existing duct system with Terrebonne, Laval, Montréal, Longueuil, on the North Shore or South Shore.

However, it should not be used to conceal a poor duct system. If a duct is seriously restrictive, we must correct the mechanical problem rather than rely solely on the fan.

MERV 13 filtration: more filtration also requires proper pressure management

Midea provides a module that can accommodate MERV 13 filters that are 1, 2, or 4 inches thick, depending on the configuration. The documentation mentions increased capture of dust, pollen, particles, and pet hair or dander.

A more efficient filter can nevertheless create greater air resistance.

That is why we always seek a balance between:

filtration quality + airflow + filter surface area + static pressure.

Choosing only the highest MERV rating without considering the system is not a good method.

Useful control options when wiring runs through an existing home

Running a new cable through an attic is one thing. Then bringing that cable down to the thermostat through finished walls can become much more complex.

Midea has provided several control architectures for the EVOX G3, including communication 485 as well as certain configurations using a conventional third-party thermostat 24 V. The platform can also use adapted communication between certain EVOX components.

This flexibility can help during a modernization, but we always verify the actual compatibility of the components before deciding which control method to use.

R454B: the EVOX G3's A2L generation

The documentation provided for the EVOX G3 indicates the use of R454B refrigerant, classified as A2L, with a global warming potential announced by Midea of 466.

For our technicians, this development involves using methods and equipment suited to A2L refrigerants, as well as complying with the manufacturer's requirements.

In an installation like the one in Terrebonne, the refrigerant lines must also be routed carefully through a space where wooden framing and other installations limit the available path.

The mistakes we particularly aim to avoid in an attic

Installing the unit without considering the next service call

A machine may fit into the space while being virtually impossible to repair.

We therefore check the panels, clearances, and accessibility of the important components.

Neglecting water protection

An installation above a ceiling requires careful condensate management. The pan visible beneath the Terrebonne unit clearly illustrates the importance given to this area of the project.

Crushing the ducts to gain a few centimeters

An attic often lacks space, but deforming or compressing the ducts to make room can considerably reduce airflow.

Choosing too much auxiliary heating

The system can accommodate substantial electrical capacities, but these must correspond to the load calculation and the capacity of the electrical panel.

Assuming that all EVOX G3 units have the same efficiency

The SEER2, HSPF2, and heating capacity depend on the exact combination of models.

LogisVert: eligibility cannot be determined solely from the name EVOX G3

For installations carried out in Quebec as of November 26, 2025, Hydro-Québec indicates that heat pumps must, among other requirements, be ENERGY STAR certified to qualify for LogisVert financial assistance. The program uses a list and a search tool to verify eligible equipment based on the installation date and the homeowner's circumstances.

The exact combination of the indoor unit and outdoor heat pump must therefore be verified, along with the program conditions applicable to the project.

In the case of our photo from Terrebonne, the complete indoor unit number is not sufficiently legible, and the outdoor unit is not shown. Therefore, based on this image alone, we cannot reliably assign a specific LogisVert amount to this project.

This is an important distinction: MIDEA EVOX G3 refers to a product line, while eligibility and the amount are tied to the specific models and the rules in effect on the project date.

An installation that shows the real work behind a central system

This photograph from Terrebonne is interesting precisely because it was not taken after the tools had been put away and the site had been completely closed up.

We can still see the technician in the attic, the structure around them, the horizontal unit between the wooden framing members, and the various constraints that must be resolved before commissioning.

For us, it is an accurate representation of a electric furnace and central heat pump installation : the manufacturer's stated performance is only the starting point.

To obtain a truly high-performing system, we must also successfully complete:

• the equipment placement;
• the mechanical support;
• the drainage;
• the duct connection;
• the airflow;
• the refrigerant connections;
• the controls;
• auxiliary heating;
• access for servicing.

To Terrebonne, as in our projects in Montreal, Laval, Longueuil, on the North Shore and the South Shore, we seek to integrate the system into the home rather than forcing the home to adapt to a standard configuration.

It is precisely in an attic as tight as this one that the difference between simply installing a unit and carrying out a true professional HVAC installation becomes the most visible.