In Saint-Bruno, a MIDEA EVOX G3 integrated between the existing ducts and the water heater in a mechanical room where every inch counted
This MIDEA EVOX G3 electric furnace installation in Saint-Bruno, on the Montreal’s South Shore, illustrates a scenario we regularly encounter at AirGreen: the new equipment has all the features sought to modernize a central system, but the available space looks nothing like a new, open mechanical room.
In the job-site photo, the situation is immediately apparent. The new indoor unit MIDEA EVOX G3 occupies a narrow space between a passage opening on the left and a substantial section of existing galvanized ducts on the right. A few inches farther away is also the home’s water heater. The MIDEA cabinet is therefore installed in a true mechanical corridor where the location of each component affects access to the others.
That is precisely what makes this project interesting.
We did not merely have to install a new electric furnace. We had to integrate it into the existing ventilation network, work around the home’s infrastructure, and maintain a configuration that was accessible enough for inspections and future HVAC maintenance work.HVAC maintenance.
The photograph also clearly shows the black fasteners connecting the different sections of the EVOX G3. They are part of the modular design of this new generation of MIDEA units, a feature that is particularly advantageous when a furnace must be installed in a space like this.
A central replacement where the room’s geometry dictated much of the work
When a homeowner compares central heat pumps and electric furnaces, attention naturally focuses on BTUs, SEER2 ratings, consumption, or heating capacity in cold weather.
On the job site, we must add another variable: the building’s actual geometry.
In this Saint-Bruno installation, we specifically had to contend with:
- very limited side clearance;
- a an immediately adjacent vertical metal duct for the new unit;
- ducts already built and integrated into the building;
- a water heater positioned nearby;
- limited clearance in front of and around the equipment;
- a connection to the existing ductwork above the unit.
This configuration requires precise planning. A difference of a few inches in cabinet width or in the position of a transition can complicate access to the furnace, water heater, or ductwork.
We therefore need to think both about current operation and about the next technician who will open the unit several years later.
The EVOX G3's modular design becomes a real advantage in this type of space
The most obvious feature in the photo is the sectional construction of the MIDEA EVOX G3.
MIDEA describes this architecture as a locking modular system that allows for several installation configurations. The documentation specifically provides for the positions upflow, downflow, right horizontal, left horizontal, as well as low-boy applications, for a total of six possible configurations. The manufacturer also emphasizes that this design makes it easier to handle the unit in basements, attics, and other hard-to-access spaces.
In our installation of Saint-Bruno, the joining fasteners between the modules are directly visible on the front.
This construction is particularly appealing to us during a replacement because a large one-piece appliance can be very difficult to transport into a finished home. Access to the mechanical room may involve a narrow door, a staircase, a tight turn, or a relatively low ceiling.
Being able to work with a modular unit makes handling easier and reduces the risk of having to unnecessarily modify the surroundings simply to get the equipment through.
MIDEA also provides simplified reconfiguration options and a layout low-boy for applications where height is limited.
Cabinet width: a detail that can completely transform a replacement project
Another interesting aspect of the EVOX G3 is its design, which is intended to make replacing certain older central furnaces easier.
According to MIDEA documentation, the different capacities use cabinets approximately 14.5 to 21.5 inches wide, with dimensions designed to better match those of several existing furnaces.
In the Saint-Bruno photo, it is immediately clear why this feature is important.
The MIDEA cabinet is practically flush with the adjacent ductwork. A few additional inches could have required a much more significant modification to the sheet metal or equipment positioning.
During an electric furnace installation on the South Shore, so we never check capacity alone. We also consider:
The unit’s width
It directly affects the required space and the type of metal transitions that must be fabricated.
The depth
This partly determines the remaining space for moving around in front of the system and removing the panels.
The total height with the transitions
A furnace does not end at the top of its cabinet: it must then connect to the plenum and the home’s ductwork.
The location of the service accesses
An installation may physically fit in the room while becoming impossible to service if the front panel is blocked.
The existing ductwork was part of the project, not merely part of its décor
To the right of the MIDEA EVOX G3, the photo shows an extensive network of existing galvanized sheet metal.
Several sections, transitions, and sealed joints can be distinguished. Some openings were also sealed or adapted over the course of the installation.
When replacing an old furnace, keeping the existing ductwork can make perfect sense if it is compatible with the new system’s requirements. However, we must verify that it can carry the required airflow.
This is a fundamental point.
Installing a modern central heat pump on overly restrictive ductwork can lead to:
- high static pressure;
- insufficient airflow;
- more noise;
- poor distribution between rooms;
- less efficient blower operation;
- less uniform temperatures;
- unnecessary motor strain.
The system’s new technology must therefore be adjusted to the existing infrastructure, rather than simply connected to it.
Computational Constant Airflow 2.0: a feature that is particularly relevant in renovations
The MIDEA EVOX G3 incorporates what the manufacturer calls Computational Constant Airflow 2.0.
The principle is to allow the blower to adjust its operation according to the resistance encountered in the ductwork. MIDEA documentation illustrates situations in which the system maintains a target airflow despite a change in external static pressure of 0.4 to 1.2 in. of water column.
The system also allows up to 60 air-volume adjustment levels, giving us much finer configuration control than many older furnaces with only a few fixed speeds.
In an existing home Saint-Bruno, this flexibility is valuable because the ductwork was not built specifically for the new unit.
But we insist on an important distinction: the motor's ability to compensate for a certain amount of pressure never justifies neglecting the ductwork.
If a return-air duct is genuinely too small or a transition has a significant restriction, that restriction must be corrected.
The goal is not to ask the motor to compensate for a poor installation. The goal is to allow it to optimize a properly adapted duct system.
Why the unit is called an electric furnace even though it also operates with a heat pump
In common Quebec terminology, the indoor unit installed in a ducted home is often called an electric furnace.
The MIDEA EVOX G3 is technically a central air-handling unit that can incorporate auxiliary electric heating and operate with a heat pump.
When a complete central system is installed, the heat pump can provide the primary heating across a large portion of outdoor conditions. Electric heating supplements the capacity when the system control calls for it.
MIDEA offers a three-stage auxiliary assembly for the EVOX G3 range, reaching up to 25 kW three stages reaching up to 25 kW. The manufacturer states that this configuration allows for gradual activation based on temperature changes and better modulation of the use of resistance heating.
Why a 25 kW element is not automatically the best choice
The maximum available output in a product range should never automatically become the installed output.
We must take into account:
- of the home's electrical capacity;
- of the calculated heating load;
- of the outdoor heat pump model;
- of its low-temperature performance;
- of the number of configured stages;
- of the auxiliary heating strategy.
An oversized electric element may require a much larger electrical supply, even though that additional power will almost never be needed.
At AirGreen, we therefore consider the system as a whole rather than simply using the highest value because it exists in the catalog.
A platform developed for cold-climate heating
For a Saint-Bruno and the South Shore, cold-weather heating capacity is obviously a major consideration.
MIDEA announces for the EVOX G3 a continuous heat pump operation down to -30 °CIts documentation also shows, in the tests mentioned for a three-ton system, up to 100% heating capacity at -25 °C, with a COP reaching approximately 1.9 under those conditions.
This precision about the tested system is important.
The value must not be automatically applied to every EVOX G3 capacity. An 18,000 BTU combination and a 54,000 BTU combination do not necessarily have the same capacity curve or efficiency ratings.
We must always examine the exact indoor unit/outdoor unit pairing.
A range from 18,000 to 54,000 BTU/h
The documentation provided by MIDEA lists several nominal capacities for this generation:
- 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 photograph of our Saint-Bruno installation does not show a rating plate that is legible enough to identify the exact model with certainty.
We therefore do not publish a capacity estimated from the cabinet size.
Two units of relatively similar dimensions may belong to different capacities. To confirm an installation, always use the rating plate and full model number.
Efficiency really does vary from one capacity to another
Depending on the combinations presented in the documentation, the EVOX G3 range reaches up to 19 SEER2, 12.5 EER2, 10.8 HSPF2 and a COP of up to 2.14 at 5°F, or approximately -15°C.
However, the manufacturer’s technical table shows significant variations.
For example, the listed 30,000 BTU combination shows 17.2 SEER2 and 10.8 HSPF2, while the 36,000 BTU capacity is listed at 17.7 SEER2 and 10.0 HSPF2. The 48,000 and 54,000 BTU capacities, meanwhile, show 17.5 SEER2 and 9.5 HSPF2 in the provided table.
That is why we avoid simply saying that an EVOX G3 is “a 19 SEER2 furnace.”
The precise figure belongs to a precise combination.
The visible details in Saint-Bruno show why the installation matters as much as the equipment
The nearby water heater also imposes access limitations
To the right of the duct section, we can see the home’s water heater.
It is not directly related to the heat pump’s operation, but it is part of the reality of the mechanical room.
A proper installation must preserve reasonable access to existing equipment.
We do not want a future water heater replacement to require dismantling part of the furnace, nor do we want work on the ductwork to make the furnace inaccessible.
When several pieces of equipment occupy a small room, The spatial organization itself becomes an element of HVAC workmanship quality.
Sheet metal joints: small details, major consequences
The various joints in the duct visible in the photo are sealed.
A duct system that leaks unnecessarily into the mechanical room sends some of the conditioned air where it is not needed and can disrupt the intended pressure in the ductwork.
We therefore pay attention to:
- transition connections;
- joints between sections;
- old openings;
- points where the sheet metal has been modified;
- areas that may produce vibrations or air leaks.
A perfectly sealed joint does not change the machine’s SEER2 rating, but it directly contributes to ensuring that the home actually benefits from the air produced by the equipment.
MERV 13 filtration: useful provided the ductwork is suitable
MIDEA provides a module that can accommodate 1-, 2-, or 4-inch MERV 13. The manufacturer indicates that this filtration can capture more dust, pollen, particles, and pet hair or dander, while helping keep the evaporator cleaner.
However, we must select the filtration based on the available surface area and airflow.
In an installation where space is as limited as the one shown in Saint-Bruno, we must also ensure that the filter remains accessible enough to be replaced regularly.
An excellent filter that is difficult to remove easily often ends up being replaced less frequently than it should be.
A new generation operating with R454B
The EVOX G3 product line presented by MIDEA uses R454B refrigerant.
For this A2L refrigerant, the manufacturer indicates a global warming potential, or GWP, of 466.
This transition to R454B involves adapted installation and service procedures.
The refrigeration connections, leak tests, evacuation, and commissioning must be carried out in accordance with the manufacturer’s requirements and applicable practices for A2L refrigerants.
The quality of this part of the work is critical: even the best equipment cannot perform as intended if the refrigeration circuit is improperly prepared.
Can you get a rebate with a MIDEA EVOX G3 in Saint-Bruno?
The MIDEA documentation provided describes the performance and features of the product line, but it does not confirm this specific installation’s eligibility for Québec financial assistance programs.
For an installation in Saint-Bruno, eligibility for a program such as LogisVert must be verified based on the complete equipment combination, in particular:
- the exact indoor unit model;
- the outdoor heat pump model;
- the AHRI combination;
- the program criteria applicable at the time of installation.
The indoor furnace alone is therefore not sufficient to provide a reliable subsidy amount.
What we recommend checking before replacing a central furnace
Do not choose based solely on the number of BTUs
Sizing affects comfort, dehumidification, noise, and operating cycles.
Look at the equipment's physical dimensions
This Saint-Bruno installation clearly shows why a few inches of width or depth can make all the difference.
Have the ductwork inspected
A variable-speed unit still depends on the air-distribution system to which it is connected.
Check the electrical capacity before choosing auxiliary heating
A larger heating kit significantly increases the potential electrical load.
Plan for maintenance from the day of installation
The panels, filter, and main components must remain accessible.
Ask for the exact models
“MIDEA EVOX G3” identifies a product line, not a specific combination. The BTUs and efficiency ratings must be associated with the model numbers actually installed.
Why this Saint-Bruno installation reflects the way we work at AirGreen
This project does not stand out because of a spectacular mechanical room or an immense space. It is interesting precisely for the opposite reason: we had to successfully modernize the central system in a location already entirely occupied by the home's infrastructure.
The MIDEA EVOX G3 is positioned immediately beside the existing ductwork. The water heater occupies the adjacent space. The sheet-metal transitions had to be adapted and sealed. The modular cabinet makes it possible to use a space that we had to work with very precisely.
For us, this is where a professional HVAC installation in Saint-Bruno makes perfect sense.
We are not simply looking to replace an old box with a new one.
We must make them work together:
the heat pump, electric furnace, blower motor, auxiliary heating, ductwork, return air, filtration, controls, and electrical installation.
This is the same method we apply to our projects involving electric furnaces and central heat pumps in Montreal, Laval, Longueuil, on the South Shore and the North Shore.
The technical specifications determine what the equipment can do. The quality of the installation determines how much of that potential will actually be used in the home.