Installation of a MIDEA EVOX G3 electric furnace in Bois-des-Filions on Montreal’s North Shore, in a basement with existing ductwork and a stone wall

A MIDEA EVOX G3 installation where the real challenge was around the furnace: substantial ductwork, stone foundation, drainage, and limited workspace

This MIDEA EVOX G3 electric furnace installation in Bois-des-Filions is an excellent example of what modernizing a central HVAC system in an existing home on the North Shore of Montreal. On paper, the project may seem simple: remove or replace an indoor unit and connect the new module to the duct network. On site, the reality is much more technical.

The photo of our worksite immediately shows several constraints: an exposed stone foundation wall, a substantial galvanized sheet-metal duct network, a large vertical section with an existing grille, round ducts at the ceiling, limited clearance around the unit, and drainage that required a clean and accessible solution.

We installed the The in a vertical position, on a suitable metal base, and then we integrated the refrigerant connections, drainage, and duct transitions without turning this already dense space into an impossible-to-maintain assembly.

It is precisely in this kind of basement that the quality of an HVAC installation also becomes just as important as the unit's technical specifications.

A photo that shows much more than a new furnace

Several interesting aspects of the project are visible at the same time.

On the left, we can see the indoor unit TheImmediately to its right is a large section of existing metal ductwork. The system then rises toward the ceiling, where several round ducts distribute air throughout the property.

The configuration also includes:

• a insulated refrigerant line descending toward the coil;
• the visible copper connections in the lower section;
• a accessible condensate trap with service caps;
• a compact condensate pump installed at the base of the system;
• a sheet-metal base and transitions fabricated to connect to the existing installation;
• a PVC drainage section;
• service clearance maintained in front of the unit;
• floor protection installed during the work.

This last part is important. In a finished or semi-finished basement, our work is not limited to the equipment. We also organize our workspace to reduce the risk of dirt, marks, or damage during handling and connections.

Why this Bois-des-Filions installation was particularly interesting

The existing system already occupied a large part of the mechanical area.

On the right side, the large vertical duct obviously could not be moved arbitrarily: it is part of the home's air-distribution system. The stone wall also limits the possibilities for modification. At the ceiling, the existing ducts determine where the new unit must ultimately connect to the air distribution.

We therefore had to work with the building, and not against it.

This is an essential distinction when a homeowner compares an installation in a new home with an electric furnace replacement in Bois-des-Filions, Laval, Montréal, or on the North Shore. In new construction, we can sometimes design the mechanical room around the equipment. In a renovation, we must design the installation around several elements that are already there.

The modular design of the MIDEA EVOX G3 makes perfect sense in a basement

One of the most relevant advantages of the The is its modular design called Block N Lock.

According to MIDEA documentation, the unit is designed to be separated into easier-to-handle modules and can be configured in six different orientations, including vertical upflow, downflow, left horizontal, right horizontal, as well as “low-boy” configurations when available height is limited.

MIDEA specifically states that this design is intended to facilitate handling in difficult locations such as basements and attics, two situations in which transporting a monolithic unit can become a problem in itself.

For our teams, this represents a very practical advantage.

A central furnace sometimes has to be taken down through:

• a narrow staircase;
• a narrow door;
• a passage with a low ceiling;
• a corridor where it is impossible to turn a fully assembled cabinet;
• an already occupied mechanical room.

The ability to handle the modules more easily reduces constraints even before the connections begin.

The large existing metal duct is not something to work around without careful thought

The most prominent part of this photograph is hardly the MIDEA unit itself: it is the adjacent ductwork.

This recalls a fundamental principle of any central ducted system : the unit and the ducts must operate as a single system.

We must take into account the required air volume, static pressure, and the resistance created by:

• transitions;
• elbows;
• filters;
• grilles;
• remote branches;
• dimensional reductions;
• the previous additions to the network.

A new unit does not automatically correct the weaknesses of an old duct system.

That is why our work always includes consideration of the connections, not just the furnace's physical location.

Constant airflow technology is particularly helpful during a replacement

R-454B: the new generation is clearly identified as A2L EVOX G3 uses the technology Computational Constant Airflow 2.0.

MIDEA indicates that this function adjusts the fan's power and speed to maintain the target airflow despite changes in system resistance. The documentation describes operation of up to approximately 1.2 in. of external static pressure and up to 60 airflow adjustment levels.

In an existing home in Bois-des-Filions, this function is particularly useful.

The system resistance can change when:

• the filter begins to accumulate dust;
• some grilles are adjusted;
• the system has different lengths;
• filtration is improved;
• the static pressure is not exactly the same as with the old furnace.

The ECM fan can then better compensate for these variations.

However, we never consider this technology permission to retain an obviously inadequate system. An undersized return, a blocked duct, or an improper transition must always be properly evaluated.

The condensate pump visible at the base of the unit is not a decorative accessory

One of the most interesting details of this installation is located almost at floor level: the condensate pump.

When the indoor coil operates in cooling mode, it cools the air below its dew point and produces water. This water must be drained reliably.

When the building configuration does not allow simple gravity drainage to a suitable drain, a condensate pump may be the most practical solution.

On this installation, we can see an assembly comprising:

• the drainage connection to the module;
• an accessible trap;
• plugs allowing maintenance;
• a PVC pipe;
• a condensate pump installed on the floor.

This arrangement also facilitates future servicing.

An inaccessible trap or a drain that cannot be cleaned may function perfectly for the first few weeks, then become the source of a service call several years later. We therefore prefer to consider cleaning from the day of installation.

Why the trap is important

The trap ensures proper water drainage in the presence of pressure differences created by the fan.

Depending on the configuration of the coil and fan, improper drain installation can disrupt condensate flow.

In our work, we therefore check:

The slope

The water must move in the right direction without creating an unnecessary stagnant pocket.

Accessibility

We must be able to clean the system without dismantling the entire installation.

Sealing

The connections must prevent leaks in the mechanical room.

The pump

When necessary, it must be installed in a location where it can be inspected and replaced without significantly moving the equipment.

In the Bois-des-Filions photo, the entire drainage assembly remains clearly visible and accessible.

A properly insulated refrigerant line also protects the building

The large pipe running down in front of the side of the system is covered with continuous insulation.

This is necessary because its temperature may be low enough to cause condensation on an uninsulated pipe.

In a basement, this repeated condensation could wet:

• the ducts;
• the adjacent materials;
• the floor;
• certain electrical components.

Properly installed insulation also helps limit unnecessary heat exchange between the refrigerant and the surrounding air.

In a tight space, however, we must strike a balance: protect the lines while avoiding blocking access to the panels and service valves.

What the MIDEA EVOX G3 brings to a Bois-des-Filions home when properly integrated with a central heat pump

A central platform designed for multiple capacities

The name The refers to a range rather than a single capacity.

The technical documentation presents systems ranging from approximately 18,000 to 54,000 BTU/h of nominal cooling capacity, depending on the combination of the indoor unit and the outdoor heat pump.

The nameplate of the photographed unit is not legible enough for us to reliably confirm the exact capacity installed at this site. We therefore prefer not to turn a visual estimate into a technical specification.

In our work, the appropriate capacity depends in particular on:

• the property's heat load;
• insulation level;
• heated area;
• fenestration;
• exposure;
• available duct airflow;
• heating needs in very cold weather.

The right capacity is not necessarily the largest capacity available.

Efficiency ratings that vary depending on the exact combination

According to the configurations presented by the manufacturer, the EVOX G3 range reaches up to:

• 19 SEER2;
• 12.5 EER2;
• 10.8 HSPF2;
• a COP at 5°F (-15°C) of up to 2.14.

The table on page 11 of the brochure also confirms that these values are not identical for every capacity: the 18,000, 24,000, 30,000, 36,000, 48,000, and 54,000 BTU systems have their own performance ratings and model numbers.

That’s why we always recommend comparing the indoor and outdoor model numbers, rather than merely the words “EVOX G3” on two quotes.

A heat pump designed for North Shore temperatures

When paired with a corresponding EVOX Extreme Heat heat pump, this system is designed to operate at very low temperatures.

MIDEA announces continuous operation down to -30 °C. The manufacturer also indicates up to 100% heating capacity at -25 °C, with a COP of approximately 1,9 under the conditions specified in its documentation.

These data are particularly relevant in Bois-des-Filions and on the North Shore, where a heat pump's winter capacity deserves as much attention as its summer efficiency.

When selecting a central system, we therefore do not limit ourselves to asking how many tons it produces in cooling. We also want to know what it can deliver when the outdoor temperature truly drops.

Auxiliary electric heating: up to 25 kW available, but the maximum is not always the right choice

The EVOX G3 range can accommodate a three-stage auxiliary electric heating kit rated up to 25 kW. MIDEA offers 10, 15, and 25 kW options and specifies that activation can be adjusted progressively according to temperature needs.

In a Quebec home, this auxiliary heating may be used:

• when demand temporarily exceeds the heat pump's capacity;
• during certain defrost conditions;
• as backup heating;
• during a request for rapid temperature recovery.

However, we do not automatically choose the largest element.

The power must be matched to the heating load and the property's actual electrical capacity. Oversizing the auxiliary heating can unnecessarily increase power demand.

A design intended to replace existing central equipment

Page 5 of the MIDEA documentation emphasizes renovations and replacements.

The EVOX G3 is available in widths of approximately 14.5 to 21.5 inches, corresponding to the standard dimensions of existing central units. The range also uses a multivoltage architecture on the relevant modules to facilitate integration with different installations.

On a project like the one in Bois-des-Filions, this compactness is valuable.

The photo clearly shows that we did not have an empty four-by-four-meter room. We had a space already structured by the ductwork, foundation, and existing installations.

24 V control or communication: valuable flexibility for renovations

MIDEA offers several control methods for the EVOX platform.

The documentation mentions communication 485 ainsi que la compatibilité avec des systèmes as well as compatibility with systems 24 V

and certain third-party thermostats. The system can also recognize the type of control in certain configurations.

During renovations, this can prevent unnecessary work.

If an existing cable is suitable and compatible with the selected configuration, we can sometimes retain part of the infrastructure instead of opening several finished walls.

• Each case is nevertheless different. We always check:
• the number of conductors;
• the thermostat type;
• the heating stages;
• the heat pump functions;

the auxiliary heating strategy.

R-454B: the new generation is clearly identified as A2L The MIDEA EVOX G3 uses the refrigerant R-454B 466 in the documented range. MIDEA indicates a global warming potential of

and classifies this refrigerant as A2L.

For the homeowner, this change has little impact on daily use.

For our technicians, however, it requires following procedures and practices suited to A2L refrigerants.

We therefore do not treat a new R-454B system exactly like an older R-410A installation.

MERV 13 filtration can be worthwhile, but only with a system capable of supporting it The range includes filtration modules that can accommodate filters of, including media MERV 13. MIDEA highlights their ability to capture more dust, pollen, particles, and pet-related contaminants.

Nevertheless, we always check static pressure before recommending more restrictive filtration.

A higher-performance filter installed on a surface that is too small can reduce airflow. In an existing system like the one seen in Bois-des-Filions, analyzing the complete system therefore remains essential.

LogisVert: the complete heat pump must be eligible, not just the furnace

For a homeowner of Bois-des-Filions, the question of the Hydro-Québec rebate often comes up very quickly when replacing a central system.

In 2026, Hydro-Québec requires that heat pumps installed since November 26, 2025 are certified ENERGY STAR to be eligible for the Heat Pump measure under the LogisVert program. When all conditions are met, the incentive is $50 per 1,000 BTU/h at -8°C for an ENERGY STAR heat pump and $120 per 1,000 BTU/h at -8°C for an ENERGY STAR Cold Climate heat pump.

The amount is therefore not calculated based simply on the nominal capacity listed as “3 tons” or “36,000 BTU.” Hydro-Québec uses the recognized capacity at -8°C for the eligible system.

The indoor furnace must also be distinguished from the complete system. Hydro-Québec notably indicates that Replacing only one indoor or outdoor unit is not eligible. to this measure.

That is why we verify the exact match, ideally using the corresponding AHRI number or ENERGY STAR identifier, rather than promising a rebate simply because the equipment bears the name MIDEA EVOX G3. Hydro-Québec also recommends using AHRI to quickly search for an eligible combination.

What we would absolutely avoid on a similar installation

Installing the furnace before planning the drainage

In this space, the pump and trap occupy a specific area at the base of the system. If we had waited until the end to think about the drain, its routing could have become unnecessarily complicated.

Blocking access to the connections with the refrigerant lines

Insulated lines must be protected, but they must also leave technical access points usable.

Reducing the ductwork abruptly to connect to the new unit

An improvised transition can increase noise and static pressure.

Choosing the capacity solely based on the old unit

Replacement equipment must be sized according to the building’s current needs.

Installing maximum electric heating without checking the panel

The availability of a 25 kW kit does not mean it is suitable for every home.

Confusing product performance with installation performance

Even the best central unit cannot compensate for poor return air, an improperly built drain, or neglected commissioning.

An HVAC renovation where the existing system becomes part of the project, not an obstacle to ignore

This MIDEA EVOX G3 installation in Bois-des-Filions perfectly sums up our approach at AirGreen.

We had to integrate a next-generation unit into an environment where the main ductwork, stone wall, and physical constraints already existed. The solution therefore required much more than a simple electrical connection.

We focused our attention on:

• the positioning of the indoor unit;
• integration into the ductwork;
• airflow;
• the refrigerant line routing;
• insulation;
• the trap;
• the condensate pump;
• service access;
• the possibility of carrying out HVAC maintenance future without having to rebuild the installation.

This is the kind of detail that makes the difference between a machine that is simply installed and a a central system properly integrated into the home.

At AirGreen, we carry out electric furnace, central heat pump, and HVAC installation to Bois-des-Filionsthroughout the North Shoreas well as the Montréal, Laval, Longueuil, and the South ShoreFor each project, we adapt the equipment to the actual building: its ductwork, mechanical space, electrical supply, and heating needs.