Installation of a MIDEA EVOX G3 electric furnace in Charlemagne

In Charlemagne, a vertical installation where the complete opening of the MIDEA EVOX G3 reveals what really makes the difference

At this installation carried out by AirGreen in Charlemagne, the photograph was taken at a particularly interesting point in the project: the panels of the new MIDEA EVOX G3 electric furnace are removed and the internal components are directly accessible. Rather than simply showing a closed and finished cabinet, this image makes it possible to see what a homeowner almost never sees once their HVAC system is in service.

We can distinguish the electronic module and its control boards in the upper-left section, the internal wiring, the large ventilation assembly in the center, the refrigeration circuit components lower down, as well as the junction between the two modular sections of the unit. Above the MIDEA EVOX G3, a galvanized sheet-metal transition connects the new unit to the home's duct network.

This vertical installation in Charlemagne, on Montreal's North Shore, illustrates an important reality very well: replacing an old furnace with a modern central system does not simply mean installing a gray cabinet between two pieces of ductwork. We must verify the mechanical integration, airflow, controls, refrigeration connections, auxiliary electric heating, and the configuration of the existing duct network before all the panels are closed.

A modern electric furnace whose interior is very different from older installations

In Quebec, we naturally use the term electric furnace to refer to the appliance that heats and circulates air through the home's ducts.

However, the MIDEA EVOX G3 belongs to a much more integrated generation of central systems. Technically, it is an air handler that can be paired with a variable-speed central heat pump and an auxiliary electric heating module.

This means that the heat can come from two complementary sources:

• the heat pump, which transfers heat through its refrigeration circuit;
• the auxiliary electric heating elements, which can operate when the heating demand increases or when the control strategy requires it.

For this range, Midea provides auxiliary heating modules capable of reaching 25 kW, with intermediate configurations and staged control to adjust the heat output to the demand.

This architecture is very different from an older electric furnace that operates mainly with heating elements and a much simpler fan.

The photo shows the MIDEA EVOX G3 during an actual stage of the work

At our Charlemagne job site, the front panels had been removed to access the components.

We can clearly observe the electronic control board, several control connectors, the wiring harnesses, as well as the compartment containing the fan. This accessibility is important for the initial installation, but it will be just as important several years later when a technician needs to perform a diagnostic or HVAC maintenance.

We can also see the modular cabinet structure. The two sections do not simply form one large monolithic box: they are connected by the mechanical system specific to the EVOX G3 design.

Midea presents this architecture as a modular, interlocking design that makes it easier to handle the different parts of the unit. The system can be configured in several ways, including upflow, downflow, right-horizontal, or left-horizontal configurations, as well as certain low-profile applications.

In Charlemagne, we were working with a vertical configuration, which matched the available ductwork and mechanical space well.

Adapt the new cabinet to the existing ductwork rather than compromising airflow

The metal transition visible above the unit is an essential part of the installation.

When the dimensions of the new unit and those of the existing system do not match perfectly, we must fabricate or adapt a transition to ensure a proper mechanical connection.

A poor transition can cause several problems:

• restricted airflow;
• turbulence;
• more noise;
• an increase in static pressure;
• uneven air distribution in the rooms.

That is why we never look only at the outside width of the new furnace.

The advantage of the EVOX G3 range is that Midea specifically worked on formats corresponding to the common widths of central systems. The documentation indicates cabinets approximately 14.5 to 21.5 inches wide, depending on the capacity, to facilitate the replacement of existing equipment.

This can reduce the modifications required, but professional adaptation of the system is often still essential.

Why we inspect the interior before closing the panels

A central system should always be inspected before it is permanently closed up.

In this photo, the unit is still in the work phase. This is precisely when we can visually confirm several elements before final commissioning.

In particular, we check:

1. the electrical and control connections;
2. the connectors for the various components;
3. the mechanical fastening of the modules;
4. the wiring layout;
5. the refrigeration connections;
6. the coil drainage;
7. the installation of the auxiliary heating when provided;
8. the compatibility of the controls and thermostat.

Once the panels are closed, the appliance must operate as an integrated system. The preparation taking place behind these panels is therefore just as important as the finished work’s exterior appearance.

A fan designed to better manage existing duct networks

The large cylindrical assembly visible in the center of the unit is the ventilation system.

It is responsible for pushing or pulling enough air through the filter, coil, and the residence’s entire duct network.

Midea places particular emphasis on its Computational Constant Airflow 2.0. It is designed to adjust the capacity and fan speed according to the resistance encountered in the network. The documentation specifies operation capable of handling up to 1.2 in. of water column static pressure under certain conditions.

The system also offers up to 60 air-volume adjustment levels, making it possible to fine-tune operation according to the installation’s needs.

For us, this possibility is particularly interesting in replacement projects in Charlemagne, Repentigny, Terrebonne, Laval, or elsewhere on the North Shore, where the duct network may be several years old.

However, an important nuance must be understood: advanced ventilation technology does not turn an undersized duct into a properly sized duct.

If a significant restriction exists, we must acknowledge it and address it as such.

A range covering several residential capacities

The EVOX G3 documentation includes several central system capacities: 18,000, 24,000, 30,000, 36,000, 48,000, and 54,000 BTU/h, depending on the combination of the indoor unit and outdoor heat pump.

However, the photograph of our Charlemagne installation does not show a sufficiently legible nameplate to confirm the complete suffix of the installed model without ambiguity.

We therefore prefer not to assign a specific tonnage to this unit based solely on its apparent size.

This point is important in our installation articles: two very similar cabinets may belong to different capacity classes.

To choose the right capacity, we consider in particular:

• the heated floor area;
• the building’s insulation;
• window area;
• heat losses;
• the airflow the ducts can actually carry;
• the heating capacity required on cold days;
• the electric backup configuration.

Oversizing equipment does not automatically make it more comfortable. The capacity must match the building.

Up to 19 SEER2 depending on the EVOX G3 combination

The product specification sheet for the range lists efficiency ratings that vary depending on the equipment pairings.

Midea announces performance of up to 19 SEER2, 12.5 EER2, 10.8 HSPF2 and a COP at 5 °F, approximately -15 °C, that can reach 2,14, depending on the combination.

The technical table in the documentation clearly shows that not all capacities have exactly the same values. For example, the listed 30,000, 36,000, 48,000, or 54,000 BTU/h systems each have their own performance data.

That is why, at AirGreen, we always talk about combination of models when a customer wants to know the SEER2, HSPF2, or precise eligibility of a central heat pump.

A system intended for cold-climate heating

In the Montreal area, a central heat pump must be seriously evaluated for its winter performance.

Midea documentation indicates advertised continuous operation down to -30 °C. It also offers, for the system used in the tests cited by the manufacturer, up to 100% heating capacity around -25 °C, with a COP that can reach approximately 1,9 under these conditions.

This represents a significant change from older generations of heat pumps, which many homeowners still associate with heating that had to be shut off as soon as the weather became very cold.

With a modern system, we instead aim to operate the central heat pump as efficiently as possible while intelligently integrating electric backup heat.

Electric heating must be properly sized, not simply maximized

Because the EVOX G3 can receive up to 25 kW of auxiliary heating, it would be easy to assume that a larger module is always better.

That is not how we proceed.

A larger electric heating element also requires a power supply capable of supporting it. The following must be taken into account:

• the electrical panel;
• the available capacity;
• the conductors;
• the protection devices;
• of the home’s heating load;
• of the heat pump’s actual low-temperature capacity.

The right choice is the one that meets the building’s demand without unnecessarily adding excessive electrical load.

The details of this Charlemagne installation that continue to matter long after our technicians leave

A modern control board requires more precise commissioning

The circuit board visible in the upper part of the unit shows just how much a modern electric furnace has become both a control system and a mechanical system.

The EVOX G3 platform is designed to operate with different communication modes. Midea specifically indicates compatibility with communication 485 and with certain configurations using a conventional thermostat 24 V.

This flexibility can be very useful during a renovation.

In some homes, the thermostat wiring is easily replaceable. In others, it runs behind several finished walls, making replacement much more complex.

The ability to adapt the control strategy to the existing installation can therefore reduce unnecessary work, provided that the selected equipment combination is compatible.

R454B: a new reality for central systems

The EVOX G3 range described in this documentation uses R454B refrigerant, classified as A2L.

Midea states that R454B has a global warming potential of 466 and states that it selected it for its range of equipment presented.

For the homeowner, day-to-day operation remains familiar. For an HVAC contractor, however, using an A2L refrigerant requires appropriate practices, equipment, and procedures.

This includes work on the refrigeration circuit, the tools used, and the manufacturer’s instructions.

More advanced filtration can be integrated into the system

The range also includes a module compatible with filters 1-, 2-, or 4-inch MERV 13, depending on the configuration. Midea states that these filters can capture more dust, pollen, and particles, as well as pet hair and dander.

However, filtration should never be selected independently of airflow.

A more restrictive filter can increase static pressure. We therefore always check whether the system, return air, and fan can operate properly with the selected filtration.

What this installation reminds us about service access

The photograph from Charlemagne also provides an excellent example of what “service access” really means.

The panels are open, and the main components are visible from the front. A technician can reach the circuit boards, fan, and other internal components without having to dismantle part of the building.

This aspect may seem secondary when purchasing a new heat pump, but it becomes extremely important during a future service call.

We recommend never blocking the front of a furnace with:

• permanent shelving;
• walls built too close;
• water heaters or appliances added later;
• boxes and stored items;
• ductwork installed in front of the panels.

A good HVAC installation must remain serviceable.

Mistakes we avoid when replacing a central furnace

On this type of project, several mistakes can compromise excellent equipment.

Relying solely on the old unit’s tonnage

An old furnace may be oversized. We must not automatically reproduce a sizing error from several decades ago.

Installing a transition that is too restrictive

A nice sheet-metal component is not enough. Its geometry must allow air to flow properly.

Neglecting the fan settings

A variable-airflow unit must be configured. Leaving unsuitable settings can cause noise, poor distribution, or reduced performance.

Installing the maximum amount of electric heating without calculations

A high-capacity module places a significant load on the electrical panel. The capacity must match the actual requirements.

Closing the unit without a complete inspection

The connections, controls, and components must be inspected before the panels are permanently closed.

This is precisely the stage of the installation shown in our photograph from Charlemagne.

And what about rebates for a MIDEA EVOX G3?

A common mistake is to assume that a complete series is automatically eligible for financial assistance as soon as a heat pump from that family has good performance ratings.

In reality, eligibility for a central system must be verified based on the exact combination of the indoor and outdoor units.

The technical documentation itself presents several different pairings, including the indoor units MAUSE associated with the outdoor units MO1HE of different capacities.

The complete model numbers of both units must therefore be used to verify certification and the applicable program criteria in Quebec at the time of installation.

Furthermore, the financial incentives described at the beginning of the supplied brochure concern programs American in California, New York State, and Oregon; they must not be used to determine the subsidy applicable to an installation in Charlemagne.

We therefore provide no specific amount for this project without the exact combination of models and validation of the applicable Quebec program.

A central installation whose quality is determined behind the panels

The photo of this MIDEA EVOX G3 in Charlemagne represents a stage that the owner will probably no longer see once the system is complete: the inside of the open machine, accessible components, and the technical work still visible.

Yet this is where much of the installation's quality is determined.

The transition to the ductwork must be correct. The modules must be properly assembled. The fan must be configured for the network. The auxiliary heating must match the building. The controls must communicate properly, and the components must remain accessible.

At AirGreen, we apply this approach to our electric furnaces, central heat pumps, and HVAC systems to Charlemagne, Montreal, Laval, Longueuil, on the North Shore and the South Shore.

A successful installation is not simply one that produces warm air when we turn on the thermostat.

It is the one that combines sizing, airflow, low-temperature heating, duct integration, connection quality, and ease of maintenance so that the system continues to operate properly long after the work is complete.