Installation of a MIDEA EVOX G3 central heat pump in Très-Saint-Sacrement, in Haut-Saint-Laurent, Montérégie

In Très-Saint-Sacrement, a central installation where every inch counted along the foundation

This installation of a MIDEA EVOX G3 central heat pump in Très-Saint-Sacrement, in Montérégie, is a good example of a project where equipment selection represented only part of the work. The home's exterior configuration imposed several visible constraints: a long vinyl façade, a relatively low foundation, a basement window located immediately behind the work area, and a side space that had to remain functional.

Rather than installing the outdoor unit directly at ground level, we carried out an installation on a raised metal support anchored to the foundation. In the site photo, the two horizontal rails supporting the heat pump, the supports beneath the unit, and the structure transferring its load to the foundation are clearly visible.

This choice offers a particularly important advantage in our climate: the base of the central heat pump remains away from the ground, snow, and ice buildup caused by defrost cycles.

The installed equipment belongs to the MIDEA EVOX G3 family, a range of inverter central heat pumps designed to work with a ducted air distribution system. The manufacturer's documentation specifically presents the EVOX G3 as a new generation of ducted central systems designed in particular to facilitate the modernization of existing installations.

An outdoor unit installed in front of a basement window without blocking the space

The photo of this installation in Très-Saint-Sacrement deserves a close look.

The heat pump is located in front of a section of the foundation where a basement window is slightly to the left. The elevated installation makes it possible to work with this configuration rather than treating the entire area as simply open space.

We also kept the front fan completely unobstructed. This is essential with the EVOX G3 since the outdoor unit uses a horizontal discharge: the volume of air passing through the heat exchanger must be able to exit toward the front without immediately encountering a wall, fence, or another obstacle.

MIDEA describes this architecture as a combination of a horizontal fan and a vertical heat exchanger, designed to promote more uniform airflow across the heat exchanger surface.

The location of this type of heat pump must therefore be evaluated in three dimensions. We must consider not only the space occupied by the unit, but also:

• the space in front of the fan;
• the clearances required for maintenance;
• the height above the ground;
• the building’s windows and other openings;
• the routing of the refrigerant lines;
• potential snow accumulation;
• defrost water drainage.

This approach is suitable in Très-Saint-Sacrement, as well as for our installations in Montreal, Laval, Longueuil, on the South Shore, and on the North Shore.

An elevated support suited to a heat pump actually used for heating

A central heat pump used only as an air conditioner could theoretically be less exposed to winter conditions. However, the EVOX G3 is designed to be used as a true heating appliance in cold weather.

During winter operation, the outdoor unit absorbs heat from the air. Frost periodically forms on its heat exchanger, and the system performs defrost cycles.

This water must be able to drain away from the unit.

If the condenser is installed very low, several freeze and defrost cycles can gradually create a mass of ice beneath the unit. Natural snow accumulation around the house adds to this.

At our Très-Saint-Sacrement installation, the space maintained beneath the unit specifically reduces this type of risk.

Clearance beneath the unit is not only a question of snow

The height also makes it easier to inspect the base, drainage, and support structure. During future HVAC maintenance, the components remain more accessible than with a unit partially buried between the ground, a slab, and winter accumulations.

We always try to think about the installation several years after it has been commissioned. An arrangement that seems acceptable on the first day can become very restrictive when a heat pump needs to be diagnosed in February.

EVOX G3 Extreme Heat: operation announced down to -30 °C

Low-temperature performance is one of the most important characteristics of this product line.

MIDEA states that the EVOX G3 provides continuous heating operation down to -30 °C. In the published results for a three-ton MIDEA system, the manufacturer also indicates up to 100% of rated heating capacity at around -25 °C, with a COP of approximately 1.9.

Compressor technology plays a central role when temperatures drop. According to MIDEA, the system uses intermediate-temperature vapor injection under extreme cold conditions to increase the total amount of compressed refrigerant and support heating capacity.

For a home in Très-Saint-Sacrement, located in an area where periods of intense cold are part of winter reality, this type of data interests us much more than a simple mention of “inverter heat pump.”

Performance varies according to the exact EVOX G3 capacity

The EVOX G3 series does not correspond to a single capacity. MIDEA offers several central configurations.

The documentation provided covers systems ranging approximately from 18,000 to 54,000 BTU/h, with efficiencies reaching:

• 19 SEER2;
• 12.5 EER2;
• 10.8 HSPF2;
• 2.14 COP at 5 °F, or approximately -15 °C.

These maximum values vary according to the specific combination of the outdoor unit and the air handler.

The G3 generation’s technical table provides, among other things, the following data:

These figures come from the third-generation EVOX G3 technical data sheet.

The exterior photo from our project site does not allow us to read the complete model number of the unit installed in Très-Saint-Sacrement with sufficient certainty. We therefore do not arbitrarily assign it a particular capacity.

For sizing, warranty purposes, and a request for financial assistance, the actual model numbers of the indoor and outdoor units must always be used.

The number of tons should never be chosen simply based on the old unit

When replacing an old central heat pump, it is common to want to order exactly the same capacity as the one already installed.

That may be appropriate, but it is not automatically the right answer.

Several factors may have changed since the previous installation: windows, insulation, an addition, how rooms are used, or air-sealing work. It is also possible that the old system was oversized from the outset.

We therefore look at the home’s actual load, as well as what the ductwork can distribute.

A higher-capacity machine generally requires greater airflow. If the ductwork cannot carry that airflow properly, simply increasing the tonnage does not solve the problem.

The EnergyGuide label visible on the heat pump

An interesting detail in the photo is the large yellow EnergyGuide label still present on the unit’s front panel.

This label illustrates the fact that energy efficiency is an integral part of selecting a modern central system. However, it does not replace AHRI data or the precise combination of the two units.

Two configurations belonging to the same EVOX G3 family may have different SEER2 or HSPF2 ratings.

We therefore work with the complete model, not just the commercial name.

Inside the house, the ductwork system and air handler are just as important as the condenser visible outside

A central heat pump never works alone

The photograph of Très-Saint-Sacrement naturally focuses on the outdoor condenser. Yet occupant comfort depends just as much on what happens indoors.

The EVOX G3 works with a central air handler and a ductwork system. It is this indoor unit that must properly circulate air to the different rooms in the house.

Poor airflow can result in colder rooms, temperature differences between floors, more noise at the grilles, or an actual capacity different from what was expected.

That is why a central heat pump installation should not be evaluated solely based on the number of BTUs.

Computational Constant Airflow 2.0: maintaining airflow despite ductwork resistance

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

According to the documentation, the fan can adjust its output to better maintain airflow when static pressure varies. The manufacturer presents examples at 0.4 in. and 1.2 in. of water column, maintaining a reference airflow under the conditions shown.

MIDEA also provides up to 60 airflow adjustment levels, accessible through the controller’s technical settings.

This adaptability is particularly interesting when a new inverter central heat pump is integrated with existing ductwork.

However, it does not eliminate the need to inspect the ductwork. A crushed duct, insufficient return air, or a highly restrictive transition remains a mechanical problem that should be corrected.

A useful modular design for Quebec basements

The EVOX G3 indoor unit is based on a modular architecture called Block N Lock.

The MIDEA brochure shows six installation possibilities, including:

• vertical with upward airflow;
• vertical with downward airflow;
• horizontal right;
• horizontal left;
• compact “low-boy” configurations.

This versatility is designed to facilitate integration into tight spaces, particularly basements and some attics.

In our replacement projects in Montreal, Laval, Longueuil, the South Shore, the North Shore, and Montérégie, this aspect has very practical value. Older furnaces are often located in places where every inch of height or width matters.

Widths designed to facilitate the modernization of an older furnace

MIDEA advertises EVOX G3 indoor unit sizes of approximately 14.5 to 21.5 inches in width, which are close in size to many residential furnaces.

The platform also provides an indoor power supply that can accommodate 115 V or 208/230 V, depending on the model and configuration.

These are interesting features when renovating, but they do not mean that a replacement is automatically a direct swap.

We must always check:

• the plenum dimensions;
• the return air;
• the available airflow;
• the electrical supply;
• drainage;
• the space required for the filter;
• auxiliary heating.

Up to 25 kW of auxiliary electric heating

The EVOX G3 platform can be paired with a three-stage auxiliary heating kit capable of delivering up to 25 kW, depending on the selected configuration. MIDEA indicates that these stages can be activated and modulated according to temperature variations.

The adjustment of this supplemental heat deserves particular attention.

If the heating elements are programmed to come on too readily, a home may consume more electricity than necessary. Conversely, insufficient supplemental heat could become problematic when the heating load temporarily exceeds what the heat pump can provide.

We therefore seek to operate the inverter as efficiently as possible while retaining the auxiliary capacity needed when conditions require it.

A platform compatible with several control strategies

The EVOX G3 documentation provides for compatibility with 485 communication, 24 V thermostats, and Sub-1 GHz wireless communication between certain compatible MIDEA components.

For a renovation, this versatility can limit the work required when routing a new communication cable between the thermostat, indoor unit, and outdoor unit would be complicated.

The thermostat choice must nevertheless be based on the desired functions. A communicating controller may offer greater access to modulation and diagnostics than a conventional thermostat.

MERV 13 filtration: useful, but it must be properly integrated with the airflow

The EVOX G3 also includes a module that can accept 1-, 2-, or 4-inch MERV 13 filters. MIDEA indicates that they can capture more dust, pollen, particles, and dander while helping keep the coil cleaner.

However, we avoid treating “higher MERV” as a universal rule.

An efficient filter creates resistance to airflow. The filter's surface area and thickness, as well as the return-air configuration, must therefore be consistent with the required airflow.

SmartHome, scheduling and consumption monitoring

With the MIDEA communicating thermostat and the SmartHome app, the documentation includes, among other things:

• schedule programming;
• temperature control;
• certain comfort- and humidity-related adjustments;
• consumption monitoring;
• diagnostic functions;
• certain remote software updates.

These possibilities are presented in the EVOX G3 brochure with the SmartHome and iCheck functions.

For a homeowner replacing an old furnace or a one- or two-stage heat pump, it is also important to understand that inverter operation is different: a long cycle at low power can be perfectly normal.

The system aims to maintain comfort with fewer fluctuations rather than constantly alternating between a complete shutdown and full capacity.

R-454B: the refrigerant selected by MIDEA for this generation

The EVOX G3 range uses R-454B, an A2L-classified refrigerant.

MIDEA states in its documentation a global warming potential, or GWP, of 466 for this refrigerant.

For the customer, this transition is seamless. For our technicians, however, it requires installation methods adapted to R-454B and compliance with the procedures prescribed for A2L refrigerants.

This includes preparing the lines, leak testing, evacuation, commissioning, and using appropriate tools.

LogisVert in 2026: the exact model and its capacity at -8 °C determine the rebate

For a residential installation completed in Québec in 2026, Hydro-Québec indicates that a heat pump installed since November 26, 2025 must be ENERGY STAR certified to qualify for LogisVert financial assistance.

When the heat pump is certified ENERGY STAR – Cold Climate, the current rebate is $120 per 1,000 BTU/h of heating capacity at -8 °C, provided that all other program requirements are met. The rebate is calculated based on the installation date.

It would be incorrect to automatically calculate the rebate for an EVOX G3 based on its nominal tonnage. Hydro-Québec bases it on the recognized capacity at -8 °C of the eligible combination.

For our Très-Saint-Sacrement project, we therefore do not publish a specific amount without the complete AHRI reference corresponding to both units.

The mistakes this installation specifically helps avoid

This project highlights several mistakes we seek to avoid in a central heat pump installation.

Installing the unit too close to the ground

A low installation can become problematic with snow and defrost water. The raised structure visible here creates clearance much better suited to winter.

Ignoring a basement window

A window, air outlet, or building opening must be taken into account from the moment the location is selected. It is much more difficult to correct this type of problem after the ducts and supports have been installed.

Obstructing the front of the fan

The EVOX G3 discharges its air forward. The front clearance visible in our installation is therefore not wasted: it is necessary for the machine to operate.

Choosing the tonnage without analyzing the ductwork

An oversized heat pump connected to a network unable to provide the required airflow is not an improvement.

Neglecting future HVAC maintenance

We want to be able to access the service panels, connections, and base of the unit without having to rebuild part of the installation.

This Très-Saint-Sacrement project sums up our approach to a central heat pump

The result visible in the photo appears deliberately simple: a MIDEA EVOX G3, a clearly defined metal support, and a façade that remains functional around the unit.

This simplicity is precisely the result of a series of technical decisions.

We had to integrate the unit into an area containing a basement window, a foundation, an exterior passageway, and the house siding. We kept substantial clearance in front of the fan and raised the condenser to better adapt it to winter use.

Inside, this type of installation must then be completed by an equally thorough check of the airflow, ductwork, filtration, auxiliary heating, and controls.

This is the comprehensive approach we apply at AirGreen when we install a central heat pump in Très-Saint-Sacrement, elsewhere in Montérégie, in Montréal, Laval, Longueuil, on the South Shore and on the North Shore.

A good installation is not only intended to make the equipment work on the day it is commissioned. It must also remain logical after several winters, several defrost cycles, and several years of maintenance.