Installation of a MIDEA EVOX G3 electric furnace in Sainte-Catherine, South Shore: vertical integration into a complex ductwork system

In Sainte-Catherine, an EVOX G3 installed at the heart of an existing HVAC system that required precise adaptation

This installation, completed in Sainte-Catherine, on Montreal’s South Shore, illustrates a reality that is highly representative of central system replacements in existing homes: the new MIDEA EVOX G3 electric furnace often has to be integrated into a mechanical environment that already includes several ducts, branches, return-air paths, and physical constraints.

The photograph was taken during an advanced stage of installation and commissioning. The upper panel of the EVOX G3 is still open, making it possible to see part of the fan, electronic boards, and control wiring. Tools are still present around the unit, and some finishing elements remain accessible. This image is particularly interesting because it shows what is normally behind the panels once the work is complete.

The MIDEA unit is installed vertically, directly beside an imposing galvanized ductwork system. Above it, several round and flexible ducts run through the mechanical room. A sheet-metal transition connects the new unit to the existing system, while the refrigerant lines run down the side panel to the coil.

In a project like this, our work at AirGreen is therefore not limited to replacing an old furnace. We must make the air handler, the heat pump, the auxiliary electric heating, the existing ductwork, the return air, the filtration, and the controls work together.

A vertical installation that takes advantage of the EVOX G3’s modularity

The MIDEA EVOX G3 is designed as a modular air handler. Its construction from separable sections is clearly visible in the photo, thanks to the fasteners located between the different modules.

This configuration allows much more freedom than a traditional all-in-one furnace.

MIDEA provides, among other options, installations:

• upflow vertical;
• downflow vertical;
• horizontal to the left;
• horizontal to the right;
• as well as various compact Low-Boy configurations.

The manufacturer presents a total of six installation options and emphasizes that the Block N Lock design facilitates handling in basements, attics, and other difficult spaces.

At Sainte-Catherine, the vertical configuration made sense because it allowed direct connection to the distribution network located above and beside the unit, while preserving a service area in front of the furnace.

The open panel reveals the true heart of the furnace

A detail rarely visible in a photograph of a completed installation is fully exposed here: the upper compartment of the MIDEA EVOX G3.

We can see the ventilation system and several electronic components in particular.

This compartment plays a major role in the operation of the central system. The fan does not simply “push air.” It must provide the appropriate airflow despite the resistance created by:

• the ducts;
• the elbows;
• the dampers;
• the filter;
• the coil;
• the different branches of the network;
• and the pressure variations between the areas of the house.

A proper commissioning process therefore involves much more than simply starting up the heat pump.

We must verify that the requested airflow matches the system’s capacity and that the duct network can actually deliver it.

Computational Constant Airflow 2.0: particularly relevant on this job

The photo of Sainte-Catherine immediately shows that we are not looking at an extremely simple, brand-new duct network. Several ducts of different sizes branch off in different directions.

This is exactly the kind of situation where the EVOX G3’s Computational Constant Airflow 2.0 technology becomes particularly valuable.

MIDEA states that the fan can adjust its operation to maintain airflow under different duct and filtration conditions. The documentation indicates an operating capability of up to 1.2 in. of external static pressure, depending on the configuration.

The system also offers up to 60 airflow adjustment levels. These settings allow the technician to fine-tune operation according to the actual installation rather than using a single setting for every home.

However, this adaptability does not mean that a poorly designed duct network can be ignored.

If a branch is too small, a return is insufficient, or a filter imposes excessive restriction, we must identify the problem. Electronic blower control is an adjustment tool, not a substitute for good ventilation design.

The existing ducts required genuine integration work

The upper and right-hand parts of the photograph show several types of ducts:

• galvanized rectangular ducts;
• round metal ducts;
• flexible sections;
• insulated sections;
• branches leading to different parts of the residence.

This diversity is typical of a property that has undergone modifications over the years.

When replacing a central system, we must determine how to connect the new furnace without creating an unnecessary constriction, excessive turbulence, or significant pressure loss.

Fabricating the sheet-metal transitions is therefore an integral part of the project.

An improperly sized transition can cause problems that the homeowner will then attribute to the heat pump: air noise, less comfortable rooms, insufficient airflow, or prolonged operation.

The quality of an HVAC installation in Sainte-Catherine often comes down precisely to these details.

A MIDEA EVOX G3 designed for modern central heating in Quebec

A range from 18,000 to 54,000 BTU/h

The EVOX G3 range covers several capacities to meet different residential needs.

MIDEA documentation presents systems of 18,000, 24,000, 30,000, 36,000, 48,000, and 54,000 BTU/h. Depending on the combination of the indoor and outdoor units, published performance can reach 19 SEER2, 12.5 EER2, and 10.8 HSPF2.

The detailed product range table confirms the different capacities and shows that efficiency varies according to each specific combination.

For this installation in Sainte-Catherine, the nameplate showing the exact model is not legible enough in the photograph to reliably confirm the tonnage.

We therefore avoid assigning an arbitrary capacity to the unit.

To determine the capacity and efficiency of a specific installation, you must always use:

1. the complete indoor unit number;
2. the exact model of the outdoor heat pump;
3. the corresponding combination;
4. the certified performance data for this combination.

A heat pump capable of continuing to provide heat at very low temperatures

When combined with the appropriate EVOX outdoor unit, the platform is designed to operate in a cold climate.

MIDEA documentation indicates continuous operation down to -30 °C. It also presents tests conducted on a three-ton system showing significant performance at very low temperatures, particularly around -25 °C.

This feature is particularly relevant for a home in Sainte-Catherine and the South Shore.

A central system installed in Quebec must be evaluated based on its performance during cold periods, not solely on its cooling efficiency.

The goal is generally to have the central heat pump handle as much of the heating as possible and use auxiliary electric heating when conditions require it.

Auxiliary electric heating up to 25 kW depending on the configuration

The EVOX G3 platform can accommodate several auxiliary electric heating capacities.

MIDEA offers, among other options, 10 kW, 15 kW, and up to 25 kW kits, with the option of staged control. The manufacturer indicates that this strategy makes it possible to adjust the auxiliary heating output according to temperature variations and the building's needs.

Installing the largest available capacity is not, however, a good sizing method.

Before selecting an electric heater, we must consider, among other factors:

• the home's heating load;
• the heat pump's low-temperature capacity;
• the type of thermostat or control;
• the electrical panel's capacity;
• the available conductors;
• the required circuit breaker;
• the property's total consumption.

A properly sized auxiliary heater helps maintain comfort without unnecessarily creating excessive electrical demand.

The Air Care Cube filtration system visible at the base of the unit

At the base of the new unit, the Air Care Cube module can be seen.

This type of cabinet facilitates the integration of a central filter while maintaining relatively direct access for replacement.

The EVOX G3 documentation provides filtration solutions of 1, 2, and 4 inches, including MERV 13 filters in appropriate configurations. MIDEA states that these filters can help capture more dust, pollen, particles, and pet hair while helping keep the coil cleaner.

The filter choice must nevertheless remain consistent with the system airflow.

A highly restrictive filter installed on an already limited return can increase static pressure and reduce the available airflow.

That is why we consider both filtration and ventilation when installing a central system.

Refrigerant lines remain accessible for servicing

The refrigerant lines are also clearly visible on this installation.

The larger-diameter line is covered with white insulation, while the smaller-diameter line remains visible nearby. They connect to the refrigerant connections on the lower module.

They run alongside the cabinet without completely blocking the main access points.

This detail becomes important several years later.

If a technician needs to check a valve, take a pressure reading, replace a component, or open the cabinet, the pipes should not turn a simple intervention into a major disassembly.

We therefore always seek to maintain a service-friendly design from the installation phase.

R-454B and A2L classification

This generation of the EVOX G3 uses R-454B refrigerant.

MIDEA states that it selected this refrigerant for its product line and mentions a global warming potential, or GWP, of 466.

R-454B belongs to the A2L category.

For the user, daily system operation remains simple: thermostat adjustment, heating, cooling, and ventilation.

For the HVAC contractor, the A2L classification nevertheless requires the use of procedures, tools, and methods compatible with this type of refrigerant, particularly during installation, leak detection, recovery, and servicing.

Compatibility with different control systems

The EVOX G3 can also operate with different control strategies.

MIDEA documentation mentions compatibility with 485 control as well as with certain configurations using a 24 V thermostat. It also describes possible wireless communication between certain compatible components to reduce the need to run new wires in some renovations.

In an existing home in Sainte-Catherine, this flexibility can be useful.

The thermostat wiring was not always designed for a modern communicating system. Being able to work with different control architectures therefore facilitates certain upgrades.

Why the system is photographed with the panel open

The image clearly shows that this installation was not simply “installed and forgotten.”

With the panel open, it is possible to access:

• the electronic boards;
• the connections;
• the fan;
• configuration settings;
• and the points required for commissioning.

This step is essential for a modern furnace.

After the mechanical installation, we still need to check the system's operation, the controls, the airflow, and the various heating and cooling sequences.

A poorly configured highly modulating unit can produce a less satisfactory result than a simpler unit that is properly adjusted.

The ventilation network must be assessed as a whole

The photograph also makes it possible to observe several branches extending around the system.

A home can have a perfectly sized unit and still have a room that is too hot or too cold if the ducts are improperly balanced.

During our interventions, we therefore pay attention to several points:

• return-air size;
• dimensions of the main ducts;
• branches leading to the rooms;
• registers;
• static pressure;
• total airflow;
• filtration;
• aerodynamic noise;
• overall condition of the ductwork.

The MIDEA EVOX G3 electric furnace has a high degree of adjustability, but it still operates within the physical limits of the system to which it is connected.

LogisVert: eligibility must be confirmed using both exact models

An installation using an EVOX G3 central heat pump could potentially be part of a combination eligible for financial assistance in Quebec.

However, eligibility must never be determined solely from the commercial name MIDEA EVOX G3.

The manufacturer's documentation presents a high-efficiency range and indicates that its product line exceeds the ENERGY STAR Most Efficient specifications mentioned in the document.

For an actual LogisVert grant application, however, we verify the information applicable in Quebec at the time of the project, including:

• the exact indoor model;
• the exact outdoor model;
• the certified combination;
• the recognized heating capacity;
• the required certification;
• the program rules in effect on the installation date.

This verification prevents promising an amount based solely on the nominal tonnage or the series name.

The mistakes this Sainte-Catherine installation helps avoid

This installation is a good example of the points that should be checked during a central system replacement.

Among the common mistakes:

• choose a furnace solely based on the dimensions of the old one;
• neglect the network’s static pressure;
• automatically keep all the old ducts without checking their dimensions;
• install an auxiliary electric heater that is too powerful for the electrical panel;
• select a filter that is too restrictive;
• block access to the panels with the refrigerant lines;
• neglect the airtightness of sheet-metal transitions;
• adjust the fan without considering the network’s actual requirements;
• promise a rebate before verifying the exact combination;
• close the unit without performing a complete commissioning.

What we take away from this AirGreen installation in Sainte-Catherine

This job clearly illustrates what it means to modernize an existing HVAC system.

The MIDEA EVOX G3 was installed in a mechanical room already occupied by a complex duct network. The new unit had to be connected to several existing sections, accessible filtration had to be maintained, the refrigerant lines had to be routed correctly, and above all, the fan had to be adjusted to reflect the actual network conditions.

The photograph taken with the panel open also shows a step that homeowners rarely see: commissioning and technical checks before closing the unit.

For us, this is an essential part of the work.

A successful central installation must be mechanically, from a refrigeration standpoint, electrically, and aerodynamically correct.

At AirGreen, we apply this method in Sainte-Catherine, throughout the South Shore, as well as in Montreal, Laval, Longueuil, and on the North Shore.

The MIDEA EVOX G3 offers an architecture particularly well suited to renovations thanks to its multiple configurations, adjustable airflow, modularity, and compatibility with different control strategies. However, the final result always depends on the quality of its integration into the building.

On this Sainte-Catherine job, it was precisely this integration that formed the heart of the project.