A MIDEA three-zone installation designed around a narrow hallway, heavily occupied walls, and three distinct comfort needs
In Saint-Sébastien, this installation of a MIDEA 28 three-zone heat pump placed us in a situation we regularly encounter in existing homes: the best location for an indoor unit is not always a large, completely unobstructed wall. Here, one of the wall-mounted units had to be integrated into a narrow hallway, directly above an opening, between two closely spaced walls, while maintaining effective airflow and reasonable access for maintenance.
The project photo clearly illustrates this constraint. The MIDEA wall-mounted unit occupies the available space above the interior opening, almost as if it had been planned during the home's construction. The ceiling already has a recessed light and a detector, the doors take up much of the side walls, and the passage must obviously remain completely clear.
Another particularly interesting detail appears on the right side of the photo: a second indoor unit is visible in the adjoining room. This image therefore perfectly summarizes the benefit of a multi-zone heat pump. We are not trying to force a single unit to serve several distant rooms; instead, we distribute heating and cooling to the areas where they are actually needed.
That is precisely the role of the MIDEA multi-zone system: a single outdoor unit can power several indoor units, each individually controllable and able to receive its own temperature setting.
Why a three-zone heat pump was particularly well suited to this Saint-Sébastien home
In a home with several separate rooms, a central hallway, or areas with different sun exposures, the temperature can vary significantly from one zone to another.
A wall-mounted unit located in a large common area can easily provide comfort on the ground floor without managing to maintain an even temperature in a closed bedroom. Conversely, oversizing a single unit in an attempt to push more air toward distant rooms rarely produces a satisfactory result.
The MIDEA 28 three-zone heat pump allows for a much more precise approach.
Each indoor unit serves its own area. A less frequently used room can be maintained at a different temperature, while a bedroom or living area can receive more heating or cooling when needed. MIDEA also indicates that its multi-zone system makes it possible to heat or cool only the spaces being used, rather than necessarily the entire home to the same level.
For our clients, this primarily translates into more logical comfort management: three zones, three needs, but a single outdoor unit.
An installation above an opening: simple in the photo, much less simple in the field
The positioning shown in this installation deserves particular attention.
A wall-mounted unit installed above a door or opening must meet several requirements simultaneously. We need enough height to properly secure the mounting plate, maintain the necessary clearances around the unit, and allow for future access to clean the filters and theHVAC maintenance.
Drainage must also be taken into account.
In cooling and dehumidification mode, the evaporator produces condensation. This water must be reliably drained. When the configuration allows it, we favor properly sloped gravity drainage, because a well-planned drain remains one of the simplest and most reliable long-term solutions.
In a corridor like the one shown in the photo, the available space is limited. Before installing the head, we must therefore establish all of the following simultaneously:
- the exact location of the indoor unit;
- the path of the refrigerant lines;
- the communication wiring route;
- the condensate drain outlet;
- access for future maintenance;
- the direction of the airflow;
- the interaction with the existing doors, trim, ceiling, and electrical components.
The final result is intentionally discreet. That is precisely the goal. A wall-mounted heat pump installation A successful installation should not give the impression that the unit was placed there simply because no other location was available.
The corridor becomes a strategic point for air circulation here
Choosing to install it above this opening also allows us to use the geometry of the corridor to our advantage.
The head is positioned high enough to project air along the path rather than directly onto a piece of furniture or into an enclosed corner. In a relatively narrow space, the direction of the louvers becomes especially important: the airflow must be able to travel through the area without creating an excessive draft for the occupants.
This question is sometimes underestimated when comparing quotes.
Two contractors can propose exactly the same MIDEA heat pump, but if the unit is installed in a less favorable location, the perceived comfort can be very different.
At AirGreen, we therefore analyze how the rooms are actually used before determining where to place the heads. We look at which doors usually remain open or closed, where occupants spend time, the furniture, windows, stairs, and the natural flow of air.
Two visible heads in the same photo: a good example of real-world zoning
The second wall-mounted air conditioner visible in the room on the right immediately helps us understand the logic behind this installation Saint-Sébastien.
Rather than asking the hallway unit to compensate for the heat loss of the entire section of the house, another zone has its own unit.
This is one of the main advantages of a multi-zone system.
According to MIDEA documentation, occupants can adjust the temperatures and operation of several spaces according to how they are used, including bedrooms, the living room, or an office.
This makes it possible, for example, to keep one bedroom slightly cooler at night while maintaining a different temperature in the common area. The same principle applies in summer when solar exposure varies from one facade to another.
MIDEA 28: an especially flexible multi-zone architecture
The MIDEA range presented in the technical documentation is not limited to wall-mounted units. It allows different types of indoor units to be combined, including wall-mounted heads, consoles, cassettes, and ducted units. The manufacturer presents the system as compatible with configurations ducted and ductless.
This flexibility becomes particularly valuable when working in existing buildings.
A house may, for example, offer an ideal location for a wall-mounted unit in the living room, but have an area where a ducted solution would be preferable. Even when the selected project uses three wall-mounted heads, working with a platform that offers several options makes it easier to design installations adapted to the building’s actual layout rather than to a single standard scenario.
The documentation also mentions systems that can be configured for up to six zones, depending on the outdoor unit’s capacity.
For this Saint-Sébastien residence, three zones were sufficient to meet the project’s needs, which makes it possible to maintain a simpler installation while achieving the desired control in the areas concerned.
The technical details behind a proper installation: sizing, Inverter technology, and commissioning
Three indoor units do not mean three independently operating compressors
It is important to understand how a triple-zone heat pump.
The three indoor units share the capacity of the same outdoor unit. They can receive different settings, but the heating or cooling output always comes from the same outdoor circuit.
That is why sizing is not simply a matter of adding three BTU figures.
MIDEA specifies in its combination rules that when the total capacity of the indoor units exceeds the outdoor unit’s rated capacity, the available output for each unit may be reduced when multiple zones simultaneously demand their full capacity, a phenomenon that is particularly noticeable in heating.
This concept directly influences how we design an installation.
We want each zone to be adequately sized, but we also avoid unnecessarily multiplying oversized indoor units. A bedroom, a corridor, and a large open area do not have the same heating and cooling load.
The capacity of each indoor unit must correspond to the room, not just its area
To select an appropriate capacity, we consider, among other things:
the room’s area and volumebut also the quality of the insulation, sun exposure, the number of windows, whether there is an upper floor, exterior-facing walls, air leakage, and how the occupants use the space.
This is particularly important for homeowners comparing a 9,000 BTU, 12,000 BTU, or 18,000 BTU heat pump.
The highest number is not automatically the best choice.
MIDEA documentation also shows that multi-zone systems support different combinations of indoor units. For three-connection configurations, the range includes several capacities of wall-mounted units, as well as options with cassettes, ducted units, or consoles.
The goal, therefore, is to build a coherent combinationrather than simply installing the maximum possible BTU capacity in each room.
Inverter technology: adjusting output rather than operating only in on-off mode
Inverter technology is another important difference.
MIDEA states that its multi-zone system can adjust its capacity as conditions change by modulating the operation of the compressor and fan motors. When not all rooms require their full capacity, the unit can operate at partial load.
In a three-zone home, this modulation capacity is particularly useful.
In the morning, one zone may require more heating. Later, sunlight may reduce demand in that room while another area begins to require heat. The outdoor unit then adjusts its operation to the system’s overall load.
This modulation logic also helps explain why a heat pump should not be selected based solely on its maximum capacity.
SynchroConnect: an interesting MIDEA feature during multi-zone commissioning
A multi-zone installation has more connections than a single-zone system. Each indoor unit has its own refrigeration lines and electrical or communication connections to the outdoor unit.
MIDEA documentation presents the technology SynchroConnectdesigned to help verify and synchronize the connections between the wiring and the refrigeration circuits of the indoor units.
For the homeowner, this technology is obviously not visible once the work is complete.
However, it illustrates an important aspect of installing a three-zone heat pump: commissioning must be carried out methodically. We check each zone individually, the operation of the controls, communication between the units, drainage, fan behavior, and the system’s overall performance.
An attractive but poorly configured installation remains a poor installation.
Indoor noise level: an important detail in a hallway and near bedrooms
The photo shows that one of the units is located in a relatively compact indoor traffic area. Noise level is therefore a relevant criterion.
The MIDEA wall-mounted units from the All Easy Pro family shown in the brochure offer several fan speeds. Depending on the capacity, some versions go down to approximately 16 to 20 dB(A) at the quietest settings indicated by the manufacturer.
However, we point out that the photo alone does not make it possible to confirm the exact reference of the installed head. These figures therefore represent the characteristics of the unit family documented by MIDEA, not a reading of the nameplate of the visible unit.
This distinction is important when comparing equipment: the exact model always matters.
ENERGY STAR, AHRI reference, and subsidies in Quebec
For homeowners in Saint-Sébastien, Montreal, Laval, Longueuil, the North Shore, or the South Shore, the amount of financial assistance can influence the choice of a heat pump.
However, a common mistake must be avoided: assuming that a brand or an entire product line automatically qualifies for the same subsidy.
MIDEA documentation contains specific tables for ENERGY STAR combinations, which shows that qualification depends on the precise pairing of the outdoor unit and the indoor units.
The manufacturer also provides AHRI reference numbers for different configurations. For example, the documentation presents a three-zone Extreme Heat combination with the outdoor unit MO3HX-H18B-2A and three 6,000 BTU/h All Easy Pro units, associated with reference AHRI 215471457.
This does not mean that this combination is necessarily the one pictured in Saint-Sébastien. The outdoor unit’s nameplate and the complete references for the three indoor heads are not visible in the image provided.
At AirGreen, we therefore prefer to verify the actual combination being proposed before confirming certified performance or eligibility for a subsidy program.
What this Saint-Sébastien installation demonstrates particularly well
This installation is interesting because it does not rely on an ideal situation created specifically for the heat pump.
We worked with the existing architecture.
The corridor is narrow. Several openings occupy the walls. The ceiling already contains electrical devices. The areas to be treated are not all in the same place. Despite this, we were able to integrate an indoor unit above an opening and distribute other heads throughout the relevant areas without unnecessarily cluttering the living spaces.
The second unit visible through the door on the right also immediately illustrates the system’s logic: each zone receives its own treatment while sharing a single outdoor heat pump.
That is exactly what makes a multi-zone heat pump relevant in many existing homes.
An HVAC installation must remain easy to maintain after we leave
The final stage of our planning is not limited to the day of installation.
A wall-mounted unit will need to be cleaned. Its filters will need to be removed. The heat exchanger and blower wheel will eventually require more thorough HVAC maintenance more thorough maintenance.
Therefore, whenever the configuration allows, we avoid placing a head in a space that would make opening or cleaning it nearly impossible.
Even in this very tight area of the Saint-Sébastien home, positioning must take this reality into account.
For us, the quality of an HVAC installation is also measured several years later: stable operation, reliable drainage, reasonable access for maintenance, and consistent comfort in the intended zones.
AirGreen and multi-zone heat pump installations in Québec
This installation of a MIDEA 28 triple-zone heat pump in Saint-Sébastien is a good reflection of how we work: analyzing the building before deciding where to place the equipment, using the system’s capacity consistently, and seeking a finish that blends naturally into the home.
We carry out the same type of projects in Montréal, Laval, Longueuil, on the North Shore and on the South Shore, with configurations that vary according to the architecture of each property.
Some homes offer large, unobstructed walls. Others require an installation above an opening, in a stairwell, or in a corridor. Some need two zones; others need three, four, or more.
What does not change is our method: size the system correctly, plan the routes before drilling, position the units for good air circulation, and check each zone during commissioning.
In this project in Saint-Sébastien, the triple-zone heat pump makes it possible to serve several areas without sacrificing floor space or requiring a complete duct network. The main unit visible in the photo fits into a particularly constrained area and demonstrates that a clean installation often depends more on planning than on the amount of space available.