Installation of a MIDEA EVOX G3 electric furnace in Saint-Mathieu, on Montreal’s South Shore

In Saint-Mathieu, a MIDEA EVOX G3 installed at the heart of an existing mechanical room with a condensate pump, adapted ductwork, and preserved service access

This MIDEA EVOX G3 electric furnace installation in Saint-Mathieu, on Montreal’s South Shore, is an excellent example of what distinguishes appliance replacement from genuine HVAC integration work. The photograph taken during our AirGreen project shows a mechanical room that was already quite full: existing metal ductwork, the building structure, electrical connections, refrigerant piping, drainage, and limited clearance for movement. Our new unit had to be integrated into this entire environment without compromising airflow, access to components, or the ability to perform future maintenance.

The MIDEA EVOX G3 is installed vertically on a metal base prepared to ensure a stable installation and facilitate the connections located in the lower section. On the side and at the back, we can see the old galvanized ductwork, with several transitions and joints already present in the residence. At the bottom of the installation, there is also a particularly interesting component: a condensate pump with several connection ports, used when naturally draining water by gravity is not the most practical solution in the mechanical room.

The insulated ducts connecting to the unit, the controls, and the visible connections on the cabinet remind us that a modern electric furnace such as the EVOX G3 does not work alone. It is the indoor component of a central heating and cooling system that must communicate properly with the outdoor heat pump, thermostat, ductwork, and auxiliary heating.

A vertical installation in a room that was not built around the new furnace

In a new home, it is possible to design the ductwork and mechanical space around the selected equipment. In an existing residence in Saint-Mathieu, the approach is often reversed: the new appliance must adapt to infrastructure that is already in place.

In this photo, the constraint is easy to understand. The MIDEA EVOX G3 is positioned immediately beside a set of imposing metal ducts. Access to the unit is primarily through its front and visible side. The upper transitions must connect to the system without creating unnecessary restriction, and the lower connections must remain accessible enough to allow for technical servicing.

We must therefore consider several elements simultaneously:

• the actual cabinet width;
• the height required to reach the ducts;
• the clearance in front of the panels;
• the refrigerant line routing;
• condensate drainage;
• the electrical and control connections;
• the air return and supply;
• the space available for future HVAC maintenance.

That is exactly why we take detailed measurements before a central replacement.

The black fasteners visible on the cabinet: a central element of the EVOX G3 design

In the photograph, the large black fasteners located at the junction of the different cabinet sections are clearly visible. They are part of the modular construction of the MIDEA EVOX G3.

MIDEA presents this platform as a unit that can be configured in several ways: upflow, downflow, right horizontal, left horizontal, and low-boy configurations, with six possibilities in total. The manufacturer also emphasizes that the modular system facilitates handling in difficult spaces such as basements and attics.

This feature is particularly relevant in existing homes on the South Shore, where an old furnace may have been installed before the basement was fully finished.

A door added after construction, a narrow staircase, or a partition can make it difficult to bring in a one-piece cabinet. The EVOX G3’s modular design makes it possible to work with several sections and then assemble them in the mechanical room.

MIDEA also provides simplified reconfiguration for certain changes in position, as well as a low-boy application when the available height is limited.

Why the visible metal base beneath the unit is important

The furnace does not rest directly on the floor. We can clearly see a sheet metal base beneath the cabinet.

This type of support can serve several purposes depending on the project configuration: adapting to the return air, aligning with the ducts, creating a service space, or leveling the unit.

In a vertical installation, cabinet alignment is important. A poorly positioned unit can complicate:

• drainage;
• duct connections;
• panel opening;
• the fabrication of the transitions;
• mechanical stability.

A difference of a few millimeters at the bottom of the installation can translate into several centimeters of difference at the top when connecting to the main system.

A condensate pump clearly visible at the bottom of this Saint-Mathieu installation

The photograph also shows a condensate pump installed in the immediate vicinity of the lower part of the unit.

When the air conditioner is running, the indoor evaporator removes moisture from the air. This moisture turns into water and must be reliably drained.

In some mechanical rooms, creating a natural slope toward a drain is easy. In others, the drain location, equipment height, or room layout makes a condensate pump much more practical.

The device shown here collects the water and moves it to the appropriate drainage point.

Why we place so much importance on drainage

A drainage problem may seem minor compared with a compressor failure, but its consequences can be significant:

• water accumulation around the furnace;
• floor damage;
• condensate line blockage;
• overflow of the drain pan;
• unwanted humidity in the mechanical room;
• system shutdown when a safety device is installed.

We therefore prioritize an installation in which the pump, connections, and service points remain accessible.

A MIDEA EVOX G3 designed to more easily replace certain older furnaces

Another practical advantage of this range concerns the cabinet dimensions.

MIDEA indicates that the different EVOX G3 capacities use widths of approximately 14.5 to 21.5 inches, with a design intended in particular to directly replace several common central furnace sizes. The indoor platform is also designed for different supply voltages depending on the configuration.

This detail is much more important than it may seem.

In a mechanical room like the one shown in Saint-Mathieu, a unit that is a few inches wider may require you to:

• rebuild part of the return air system;
• move an existing duct;
• reduce the service space;
• move another piece of equipment;
• redo several sheet metal transitions.

BTU capacity is therefore never our only criterion.

We must also verify whether the equipment can be physically integrated into the home professionally.

A modern electric furnace must be selected and adjusted as part of a complete system.

“Electric furnace” and “air handler”: understanding how they work

In Quebec, the term electric furnace remains the one most homeowners use to refer to the central indoor unit.

Technically, the EVOX G3 functions as a central air handler that can operate with a heat pump and receive an auxiliary electric heating kit.

When the system is operating in heating mode, the outdoor heat pump normally produces heat through thermodynamic transfer. The electric elements can then operate as an auxiliary heat source when the demand or control parameters require it.

For the EVOX G3 range, MIDEA offers a three-stage auxiliary heating kit rated up to 25 kW. The manufacturer states that this configuration enables gradual activation and better adaptation to temperature variations.

Why we do not automatically choose the maximum electric heater

A 25 kW electric heater is not automatically preferable to a 10 or 15 kW element.

The appropriate capacity depends in particular on:

The home's heating load

A well-insulated, relatively compact home in Saint-Mathieu may require much less auxiliary heating than a larger, older property.

Available electrical capacity

Resistive heating places a significant load on the electrical panel. We must therefore verify what the electrical installation can actually support.

Outdoor heat pump performance

The more heating capacity the heat pump retains in cold weather, the less likely the auxiliary heating is to be called upon.

Our goal, therefore, is to size the system, not maximize it.

A platform designed for cold-weather heating

Winter performance is obviously essential in a region like Saint-Mathieu.

The EVOX G3 documentation states that the heat pump can operate continuously down to -30 °C. MIDEA also reports, for a three-ton system used in its testing, up to 100% heating capacity at -25 °C, with a COP reaching approximately 1.9 under the stated conditions.

The “three-ton system” detail is essential.

We must never automatically apply this result to all EVOX G3 capacities. The available heat and low-temperature efficiency depend on the exact indoor unit + outdoor unit pairing.

Several capacities are available in the EVOX G3 range

MIDEA’s technical documentation covers systems including:

• 18,000 BTU/h;
• 24,000 BTU/h;
• 30,000 BTU/h;
• 36,000 BTU/h;
• 48,000 BTU/h;
• 54,000 BTU/h.

The nameplate in our Saint-Mathieu photo is not legible enough to confirm the exact capacity of the installed unit unambiguously.

We therefore prefer not to assign a tonnage based solely on the appearance of the cabinet.

Two units of similar size may have different specifications. To determine the actual performance, you must use the complete model number.

Up to 19 SEER2 and 10.8 HSPF2, depending on the combination

The EVOX G3 range offers performance of up to 19 SEER2, 12.5 EER2, 10.8 HSPF2, and a COP of 2.14 at 5 °F, depending on the equipment combination.

However, the table on page 11 of the documentation shows that these values change according to capacity.

For example:

• the 30,000 BTU/h combination is listed at 17.2 SEER2 and 10.8 HSPF2;
• the 36,000 BTU/h combination shows 17.7 SEER2 and 10.0 HSPF2;
• the 48,000 and 54,000 BTU/h combinations are listed at 17.5 SEER2 and 9.5 HSPF2.

This distinction is important for a homeowner comparing several quotes.

A statement such as “EVOX G3 up to 19 SEER2” describes the product range. It does not replace the technical data for the combination actually installed.

The existing ductwork must be able to accommodate the new system’s airflow

The photograph shows a substantial section of the existing ductwork immediately behind the MIDEA unit.

This is a central aspect of this project.

A modern variable-speed furnace does not operate in a vacuum. It must push air through a network that may contain transitions, bends, branches, a filter, and several grilles.

If the resistance is excessive, we may observe:

• insufficient airflow;
• increased noise;
• temperature differences between certain rooms;
• excessive static pressure;
• greater strain on the fan.

Computational Constant Airflow 2.0: a particularly useful feature when replacing a system

MIDEA equips the EVOX G3 with its Computational Constant Airflow 2.0 technology.

The documentation provides examples in which the system adjusts capacity and fan speed to maintain airflow despite changes in resistance. MIDEA specifically illustrates conditions ranging from 0.4 to 1.2 in. of external static pressure.

The platform also provides up to 60 air-volume adjustment levels.

This flexibility is useful when a new furnace is connected to existing ductwork, as in Saint-Mathieu.

However, we never consider this technology an excuse to keep an inadequate duct system.

If a significant mechanical restriction exists, it must be corrected. The goal is to use the EVOX G3's adjustment capability to fine-tune a good installation, not to conceal an inadequate duct system.

R454B: the refrigerant used by this new generation of MIDEA systems

The EVOX G3 lineup operates with R454B, an A2L refrigerant.

MIDEA indicates a global warming potential, or GWP, of 466.

This new generation of refrigerant requires appropriate work methods during installation and service.

Refrigerant connections, leak tests, evacuation, and commissioning must be performed in accordance with the manufacturer's requirements.

The photograph from our worksite also shows the importance of properly organizing the connections around the cabinet: several ducts and cables converge in the same area, while still needing to remain protected and accessible.

Control compatibility: useful during modernization

MIDEA also indicates that the platform is compatible with 485 communication or traditional 24 V controls, with automatic identification of the control mode in configurations specified by the manufacturer.

In replacement projects, this flexibility can be useful when part of the existing wiring needs to be reused.

However, this does not mean that every thermostat will provide access to all functions.

The number of stages, auxiliary heat, heat pump, fan control, and smart functions must be checked as a whole.

MERV 13 filtration: efficiency and static pressure must remain balanced

The EVOX G3 can be paired with a module compatible with 1-, 2-, or 4-inch MERV 13 filters. MIDEA states that this filtration can capture more dust, pollen, particles, and pet hair or dander, while helping keep the evaporator cleaner.

However, the filter must be properly sized.

Installing a highly restrictive filter in a small filter area can increase static pressure. The filter choice must therefore be consistent with the system airflow and return configuration.

The errors illustrated by this Saint-Mathieu installation

Choosing solely based on BTUs

The tonnage must match the building, but the physical dimensions and ductwork system must also be compatible.

Neglecting drainage

A properly installed condensate pump can be essential when gravity drainage is difficult.

Blocking the panels with pipes or cables

The system must remain accessible for several years after installation.

Installing an oversized auxiliary heater without checking the electrical panel

The maximum available capacity is not automatically the appropriate capacity.

Using the highest SEER2 rating in the entire product line in a quote

Performance varies according to the exact combination.

Assuming eligibility for financial assistance based solely on the EVOX G3 name

The documentation provided by MIDEA describes the product line, but does not by itself confirm this specific installation’s eligibility for a Quebec program. The indoor model, outdoor model, and AHRI combination must be verified according to the rules in effect at the time of installation.

An AirGreen installation designed around the equipment, but also around the home

This MIDEA EVOX G3 electric furnace installation in Saint-Mathieu illustrates our philosophy at AirGreen well.

We do not consider the new furnace an independent component.

On this project, we had a modern unit to integrate into an existing ductwork system, a base to adapt, a refrigerant circuit to organize, condensate drainage requiring a pump, and several connections that needed to remain accessible.

Once the panels are closed and the project is complete, much of this work becomes almost invisible.

Yet this is precisely where the quality of an HVAC installation is determined.

We apply this same method in our installations of electric furnaces, central heat pumps, and HVAC systems in Montreal, Laval, Longueuil, the South Shore, and the North Shore: selecting the right capacity, checking the ductwork, organizing the connections, preserving technical access, and configuring the airflow according to the building’s actual conditions.

The technical potential of a MIDEA EVOX G3 is significant. But this potential is only truly useful when it is properly integrated into the home.