A compact mechanical room where every connection had to be planned before commissioning
In Lorraine, on Montreal’s North Shore, we installed an MIDEA EVOX G3 electric furnace in a mechanical room that perfectly sums up one of the most common challenges in residential renovations: integrating a new generation of central equipment into a space already occupied by ductwork, drainage plumbing, refrigerant lines, and the electrical panel.
The photograph taken during our work clearly shows the result. The new MIDEA indoor unit is positioned vertically against the existing duct network. To its left, a large metal duct rises practically from floor to ceiling. To its right, the copper lines were routed vertically along the wall, while the electrical panel is located in the immediate vicinity. At the bottom of the unit, we installed a rigid drainage connection leading to the floor drain.
This is an installation in which quality is measured not only by the appearance of the new equipment. The challenge was to make the entire HVAC system : airflow, heating, cooling, condensate drainage, service access, electrical power, and integration with the duct network already present in the home.
MIDEA’s documentation classifies the EVOX G3 among its Inverter central ducted systems, developed in particular to facilitate the modernization of existing heating systems.
A vertical installation that makes efficient use of the available space
In this home in Lorraine, the geometry of the mechanical room required a very precise configuration.
The furnace is installed upright, directly beside the imposing existing metal duct. It was not merely a matter of finding enough floor space. It was also necessary to consider:
- of the unit’s actual width;
- of the height available beneath the ductwork;
- of the position of the refrigerant connections;
- of the clearance required in front of the panels;
- of the condensate drain route;
- of the proximity of the electrical panel;
- of the return and supply air connections;
- of future access forHVAC maintenance.
It is precisely these details that can make the difference between a well-planned compact installation and one in which replacing a component a few years later becomes almost impossible.
The latches visible on the side of the EVOX G3 have a very specific function
An interesting detail appears directly in the photo: several black latches are visible on the side of the unit.
They are related to the modular design of the EVOX G3. MIDEA uses an assembly system that allows certain sections of the unit to be separated and reconfigured to facilitate transport and installation in hard-to-access locations.
The manufacturer's documentation presents this modular architecture as a solution particularly suited to basements and attics. The EVOX G3 can be configured in several positions: upflow, downflow, horizontal right, horizontal left, as well as certain configurations known as “low-boy.”
This feature may seem secondary when looking at a brochure. In the field, it becomes much more interesting.
In many homes in Lorraine, Rosemère, Blainville, Laval, and the North Shore, access to the mechanical room is through a narrow staircase or a door whose dimensions date back several decades. A unit that can be handled more flexibly provides many more options during replacement.
A new furnace connected to the ducts already present in the home
The large sheet-metal network immediately to the left of the MIDEA was one of the elements we had to work with.
When replacing a central system, we almost never start with an entirely new network. The ducts were often sized for an old furnace and then modified during successive renovations.
We must therefore verify whether the ducts can handle the airflow required by the new equipment.
A poorly designed transition can notably cause:
- noise in the ducts;
- an increase in static pressure;
- a reduction in airflow;
- less even temperatures between rooms;
- excessive strain on the blower motor;
- less efficient heating or cooling cycles.
We therefore pay particular attention to the sheet-metal connections, the tightness of the joints, and the path the air must travel before reaching the different rooms.
Why constant-airflow technology is particularly interesting in this type of renovation
The MIDEA EVOX G3 incorporates a technology that the manufacturer calls Computational Constant Airflow 2.0.
Its purpose is to allow the blower motor to adapt its operation when the system resistance changes. MIDEA documentation presents conditions of up to 1.2 in. of external static pressure, depending on the application.
The system also offers up to 60 airflow adjustment levels among the settings available to the installer.
For an existing home in Lorraine, this adjustment capability is particularly relevant.
However, this does not mean that the machine can correct every duct problem. A return duct that is much too small remains too small. A blocked damper remains a restriction. An excessively loaded filter must be replaced.
Technology gives us more tools to adjust the system correctly; it does not replace analysis of the duct network.
The rigid drainage visible at floor level: an essential component of central air conditioning
The lower part of this installation deserves particular attention.
We can clearly see a rigid drainage system connected to the unit and directed to the floor drain. It is much less spectacular than a new heat pump, but it plays an essential role every summer.
When the heat pump operates in cooling mode, the indoor coil becomes cold. The moisture in the air then condenses on this coil, exactly as water forms on the outside of a cold glass.
This water must be continuously drained.
On this site, the room’s layout made it possible to direct the condensate toward the floor drain. The system is therefore installed permanently rather than leaving an improvised flexible line running across the room.
Improper drainage can cause:
- water around the furnace;
- floor damage;
- moisture in the mechanical room;
- odors;
- blockages;
- system interruptions when an overflow protection device is present.
For us, drainage is an integral part of thecentral heat pump installation, just like the refrigerant lines or electrical connections.
The refrigerant lines follow the wall without blocking access to the system
To the right of the furnace, we can also follow the path of the copper lines.
They are routed vertically along the wall before reaching the indoor unit connections. The line that must be insulated is protected to limit condensation and unwanted heat transfer.
Positioning is important: we want to avoid having a refrigerant line run directly in front of a panel that will need to be opened for future servicing.
This is a simple principle we apply during our installations in Montreal, Laval, Longueuil, on the North Shore and the South Shore : what is convenient for the installer today must not become an obstacle for the service technician tomorrow.
The electrical panel is nearby, but this does not determine the auxiliary heating capacity
The photograph also shows the electrical panel on the wall to the right.
Its proximity to the equipment may potentially simplify the routing of certain connections, but it absolutely does not allow us to determine, from the photo alone, what auxiliary electric heating capacity can be installed.
The calculation must account for the available power supply, conductors, electrical protection, nameplate, and the home’s load.
MIDEA provides different auxiliary heating kits for the EVOX G3 and specifies configurations of up to 25 kW, with operation in several stages depending on the application.
Installing the greatest possible capacity is not our objective.
We are instead trying to determine the actual supplementary capacity required so that the heat pump remains the main heating source as long as its operation is advantageous.
A modern electric furnace does not operate like a simple resistance-heating appliance
The term electric furnace can sometimes cause some confusion.
In a traditional central installation, an electric furnace essentially heats the air using electric resistance elements before distributing it through the ducts.
With an EVOX G3 system paired with a heat pump, the logic is different.
The heat pump extracts heat from outdoors and transfers it indoors. The furnace or air handler circulates this heat throughout the home. Auxiliary electric heating then comes into play when the building’s needs or the control settings require it.
This strategy can significantly reduce the number of hours during which the home depends solely on electric resistance heating.
Designed to continue providing heat during extreme cold
This aspect is particularly relevant in Lorraine, where winter temperatures can drop very low.
MIDEA states that the EVOX G3 line can operate the heat pump down to -30°C. The manufacturer also reports, under certain test conditions, significant heating capacity at -25°C, with a COP of approximately 1.9. Some of these figures were obtained on a three-ton system.
In other words, this generation of central heat pump is not designed only for fall and spring.
It is also intended to operate in severe winter temperatures.
That said, the capacity actually available at a specific temperature always depends on the exact outdoor model and the pairing with the indoor unit.
What is the BTU capacity of this installation in Lorraine?
MIDEA documentation covers a wide range of capacities.
The EVOX G3 configurations presented in the technical data sheet range from 18,000 to 54,000 BTU/h, with several intermediate models. Performance varies depending on the pairing.
The nameplate is visible in our photograph, but the model number characters are not legible enough for us to assign a precise tonnage to this installation with certainty based on the image alone.
We therefore prefer not to make up a capacity.
This is an important point for homeowners shopping for a heat pump: “MIDEA EVOX G3” is a product line, not a capacity.
To properly compare two quotes, you need to obtain:
- the exact model number of the indoor unit;
- the exact model number of the outdoor unit;
- rated capacity;
- low-temperature heating capacity;
- the corresponding AHRI reference number.
Up to 19 SEER2 depending on the selected combination
MIDEA documentation presents efficiencies of up to 19 SEER2, 12.5 EER2 and 10.8 HSPF2 depending on the pairing. The COP advertised at 5°F, or approximately -15°C, can reach 2,14 for certain configurations.
It is important to read these figures correctly.
The phrase “up to” means that this is the best value in the range, not a universal value for all tonnages.
For example, the manufacturer’s technical data shows different values for capacities of 18,000, 24,000, 30,000, 36,000, 48,000, and 54,000 BTU/h.
At AirGreen, we therefore prefer to discuss the performance of the actual installed pairing rather than presenting only the best advertised rating for the product family.
The R-454B and A2L designation visible on the equipment
The unit’s nameplate also displays the labeling associated with the refrigerant A2L.
The EVOX G3 range uses R-454B. MIDEA indicates a global warming potential, or GWP, of 466 for this refrigerant.
For a homeowner, this primarily means that the system belongs to a generation of equipment requiring adapted service practices.
For us, this means using the procedures, tools, and methods appropriate for R-454B when working on the refrigeration circuit.
High-performance filtration must always remain compatible with the airflow
The EVOX G3 range can accommodate different filtration solutions. MIDEA mentions modules that allow the use of filters measuring 1, 2, or 4 inches, including MERV 13 configurations.
A higher-performance filter can capture more dust and particles, but it also creates resistance to airflow.
We must therefore consider the filter together with:
- the return size;
- the blower airflow;
- the static pressure;
- the heat pump capacity;
- the filter cabinet size.
Choosing only the highest MERV rating without checking the ductwork is a mistake we seek to avoid.
This project in Lorraine shows why a proper central installation is the sum of dozens of technical decisions
A modern machine is not enough if the surrounding details are neglected
This project is interesting because several essential elements are visible in a single photograph.
We can see simultaneously:
- the MIDEA EVOX G3;
- the existing large metal duct;
- the refrigerant lines;
- the condensate drain;
- the floor drain;
- the electrical panel;
- the base and sheet-metal connections;
- the unit’s access panels.
None of these elements operates independently of the others.
An installation can use a highly efficient heat pump and still deliver mediocre results if the airflow is insufficient. It can be perfectly sized and cause problems if the drainage is poorly designed. It can operate efficiently for several years but become unnecessarily expensive to repair if the service access points have been sealed off.
Our role is precisely to consider these interactions before startup.
Mistakes we want to avoid when replacing an electric furnace
When a homeowner in Lorraine or on the North Shore plans to replace their central system, several points should be checked even before choosing a brand.
Sizing based solely on floor area
Two homes of the same size can have very different heating loads. Windows, insulation, exposure, ceiling height, and air infiltration also matter.
Choosing auxiliary heating without checking the electrical panel
The available electrical capacity must be determined before selecting the heating kit.
Ignoring the system’s static pressure
A new blower does not automatically mean that the old ductwork is adequate.
Improvising condensate drainage
Drainage must be planned as a permanent component of the installation.
Routing the lines in front of the panels
A very tight installation must remain serviceable.
Confusing nominal capacity with winter capacity
The BTUs shown on a quote do not, on their own, indicate how much heat the heat pump will provide at -15 °C or -25 °C.
Rebate: why we need to know the exact pairing before confirming eligibility
When a homeowner asks us whether a MIDEA EVOX G3 heat pump can qualify for financial assistance in Québec, the product line name alone is not enough.
The different capacities listed by MIDEA correspond to different combinations of indoor and outdoor units.
Eligibility and the applicable amount must therefore be verified based on the exact pairing and AHRI reference, according to the program rules in effect at the time of installation.
For a project in Lorraine, we particularly recommend checking the current eligibility criteria for Hydro-Québec’s LogisVert program before considering a rebate guaranteed.
Our approach at AirGreen for central system replacements in Lorraine and Greater Montréal
This project highlights an important aspect of our work: a proper HVAC modernization is not simply a matter of replacing an old box with a new one.
We must understand the system around the machine.
In this Lorraine home Lorraine, this meant installing the furnace in a tight space, maintaining a good connection with the existing ductwork, routing rigid drainage to the floor, neatly organizing the refrigerant lines, and preserving convenient access to the components.
The result is a central system designed to provide heating, cooling, and air circulation throughout the home while using heat pump technology suited to our region’s winter temperatures.
This is the method we apply during our HVAC installations in Lorraine, Laval, Montréal, Longueuil, on the North Shore, and on the South Shore first inspect the building, ductwork, and technical constraints, then select and install the equipment so that everything operates as a single system.