A dual-zone installation in which technical performance also had to remain discreet in the room
At Venise-en-Québec, we completed an installation that illustrates very well what we look for at AirGreen when a homeowner chooses a dual-zone heat pump: achieving true control over two distinct spaces without unnecessarily multiplying the outdoor equipment, while integrating the indoor units cleanly into the home's architecture.
The system selected is a MIDEA 28 dual-zone system, with an outdoor 18,000 BTU compressor, based on model MO3HX-H18B-2A. This platform is particularly interesting because it can power two wall-mounted units in the configuration installed here, while belonging to a multi-zone family capable of managing up to three zones with this 18,000 BTU condenser when the indoor unit combinations comply with the manufacturer's tables. Midea's documentation also presents the multi-zone concept as the use of a single outdoor unit for several indoor units, each of which can be adjusted individually according to the desired temperature.
This independence between zones is much more important than it may seem. In a home, two rooms facing different directions, two floors, or even a living area and a bedroom almost never have the same thermal load at the same time. A properly sized dual-zone system therefore avoids treating the house as one uniform volume.
At this Venise-en-Québec job site, the photo of the indoor installation also shows a detail that matters greatly to us: the final result had to be clean. The Midea wall-mounted unit is positioned high on the wall, while the white line set cover containing the technical connections runs along the ceiling. Instead of leaving a visible piping route that immediately draws the eye, the entire installation follows the room's natural lines.
The MIDEA 28 18,000 BTU: what we actually have on our hands
For this dual-zone configuration, the outdoor reference associated with our MIDEA 28 is MO3HX-H18B-2A. Our AirGreen technical data sheet also identifies the combination by number AHRI 215471457, with ENERGY STAR® and ENERGY STAR® Cold Climate certification. The rated cooling capacity is 18,000 BTU/h, with heating operation down to -30 °C, R-454B refrigerant, optional Wi-Fi, a SEER2 of 25.0, HSPF2 of 10.4, and EER2 of 15.0.
Among the important data for a homeowner, as well as for the installer who must properly size the system, are:
- Outdoor model: MO3HX-H18B-2A
- Rated capacity: 18,000 BTU/h
- Project configuration: 2 zones
- Condenser capability: up to 3 zones depending on the approved combinations
- AHRI: 215471457
- ENERGY STAR® Cold Climate: yes
- SEER2: 25.0
- HSPF2: 10.4
- EER2: 15.0
- Heating: down to -30 °C
- Capacity indicated at -8 °C: 20,000 BTU/h
- Capacity indicated at -15 °C: 19,000 BTU/h
- Refrigerant: R-454B, A2L category
- Power supply: 208/230 V, single-phase, 60 Hz
- MCA: 16 A
- MOP: 20 A
- Indicated outdoor sound level: 62 dB(A)
- Condenser dimensions: approximately 37.25 × 16.13 × 31.88 in.
- Wi-Fi: optional
The Midea catalog also confirms that the Extreme Heat multi-zone systems of this generation use model MO3HX-H18B-2A for the 18,000 BTU capacity, with AHRI reference 215471457 in the ductless configuration.
A two-zone system is not simply “two heads on one compressor”
This is probably one of the most important distinctions to understand before purchasing a multi-zone heat pump.
A dual-zone installation is not sized by arbitrarily adding two indoor units. Midea permits several combinations for its 18,000 BTU condenser. In our MIDEA 28 configuration, capacity combinations such as 6,000 + 6,000 BTU, 6,000 + 9,000 BTU, 6,000 + 12,000 BTU, 9,000 + 9,000 BTU, 9,000 + 12,000 BTU, or 12,000 + 12,000 BTU may be encountered, depending on the building's needs and the approved combinations.
This point is essential because the capacity listed on each indoor head does not mean that all heads will simultaneously receive their full rated capacity under all circumstances.
Midea specifies in its documentation that when the total capacity of the indoor units exceeds the rated capacity of the outdoor unit, the actual capacity available to each unit may be reduced, a phenomenon that is particularly noticeable in heating mode.
That is precisely why we do not size a dual-zone heat pump solely based on the number of square feet.
We also examine the layout of the rooms, insulation, windows, sun exposure, natural air circulation, ceiling height, the use of each zone, and above all what is likely to happen when it is very cold and both zones simultaneously call for heating.
The detail visible in the photo: a wall-mounted unit installed very high, with well-integrated connections
The photo taken after the installation in Venise-en-Québec is interesting because it shows precisely what the customer sees every day.
The indoor unit is installed against a light-colored wall, very close to the ceiling. The white line set cover enters the upper part of the installation and extends parallel to the ceiling. The result remains visually consistent with the room: no copper piping, electrical wiring, or condensate drain line dominates the wall.
However, the high positioning of a wall-mounted head is not solely aesthetic. It must comply with the clearances required for air circulation and maintenance work.
Another very concrete detail appears on the photographed rating plate: the unit uses R-454B and bears the A2L marking. It also shows a minimum installation height of 1.8 m, or 6 ft. With the new A2L refrigerants, this rating plate information is not decorative. It is part of the parameters the HVAC technician must consider when determining the final location of a unit.
The exact reference of the indoor head is too difficult to read in this photo for us to state it with certainty. However, the MIDEA 28 range in this capacity can accommodate different wall-mounted units depending on the sizing of each zone; our specification sheet for the 18,000 BTU configuration lists, among others, the references MSEHU-H06B-2A, MSEHU-H09B-2A and MSEHU-H12B-2A.
Why R-454B also changes certain installation practices
The R-454B belongs to a new generation of refrigerants used in many recent HVAC systems. In the case of this MIDEA 28, the A2L marking is clearly visible on the head installed in Venise-en-Québec.
For our team, this means that an installation is never simply a matter of mechanically repeating the practices used for an older R-410A appliance. The procedures, tools, manufacturer requirements, and restrictions specific to the refrigerant charge and room volume must all be taken into account.
This is also why the quality of a HVAC installation becomes just as important as the product’s technical specifications. A high SEER2 rating does not compensate for poor condensate drainage, an unsuitable location, improper preparation of the refrigerant lines, or an electrical connection that does not comply with the prescribed MCA and MOP values.
Inverter modulation is especially valuable in a two-zone home
Another interesting feature of this platform is its Inverter technology.
Midea explains that the system adapts its capacity as conditions change by modulating the compressor and fan motors. When only part of the house calls for cooling or heating, the system can operate at partial load rather than running constantly at full capacity.
In a dual-zone system, this modulation capability is particularly useful.
Consider a setup in which one unit serves a living area and the other serves another part of the residence. If the first zone is already approaching its setpoint while the second still needs heating, the system can adjust its operation instead of behaving like an older all-or-nothing appliance.
Midea also emphasizes that individual control makes it possible to heat or cool occupied spaces rather than necessarily the entire home.
For the homeowner, the benefit is therefore not simply “two remote controls.” It means getting two truly distinct thermal zones powered by a single outdoor unit.
An interesting technical point for our HVAC technicians: SynchroConnect
Multi-zone installations quickly become more complex than a single-zone heat pump because each head has its own refrigerant lines and electrical connection.
Midea’s documentation presents the SynchroConnect technology in this regard. The system can diagnose whether the wiring is matched with the lines connected to the indoor units. Midea also indicates that the system can synchronize the connections between the refrigerant lines and the wires when the manufacturer’s prescribed procedure is used.
This type of function obviously does not replace a methodical installation. Rather, it provides an additional layer of verification during commissioning, which is particularly useful when several circuits leave the same condenser.
The mistakes we want to avoid with every dual-zone installation
The first pitfall is oversizing the indoor units. Installing a large head "just to be sure" is not always preferable. It can produce too much airflow for the room or reach its setpoint too quickly without promoting long, stable operation.
The second is to choose the two indoor capacities independently of each other. With a multi-zone system, the whole system must always be considered: outdoor compressor + first head + second head + simultaneous-use profile.
The third concerns drainage. A wall-mounted unit produces water in cooling and dehumidification mode. A poorly planned condensate line can eventually cause an indoor leak long after the installation appears to be complete.
The fourth is aesthetics. A heat pump can function perfectly and still give the impression of having been added hastily if the line sets are poorly aligned, if the routes change direction unnecessarily, or if the indoor unit is off-center for no reason. At the Venise-en-Québec project, the visible ceiling route shows precisely the opposite approach: we use the room's existing lines so that the installation remains as discreet as possible.
Finally, future maintenance must be considered. We must be able to access the filters and components without dismantling part of the building. A beautiful installation that becomes impossible to maintain is not a good installation.
What about the LogisVert subsidy for this MIDEA 28?
Here, two things must be distinguished: the equipment's technical specifications and the subsidy amount applicable on the actual date of the work.
The MIDEA 28 configuration rated at 18,000 BTU, bearing reference AHRI 215471457, is identified as ENERGY STAR® and ENERGY STAR® Cold Climate in our technical documentation.
Hydro-Québec currently indicates that, for heat pumps installed since November 26, 2025, the system must notably be certified ENERGY STAR®, include the eligible outdoor unit and indoor unit or units, and the outdoor unit must have a rated cooling capacity of at least 12,000 BTU/h.
The 18,000 BTU MIDEA 28 therefore meets the basic technical characteristics required to consider eligibility, but the LogisVert amount must never be determined solely from the name “MIDEA 28”.
At AirGreen, we prefer to verify the exact AHRI number of the installed combination in the Hydro-Québec list in effect at the time of the work. This approach avoids announcing an amount today based on an old subsidy schedule. Programs, amounts, and recognized combinations can change; the AHRI number is much more reliable than a simple commercial name.
Why this Venise-en-Québec installation represents the way we work
This project is not spectacular in any exaggerated way, and that is precisely what makes it interesting.
An excellent heat pump installation should ultimately integrate naturally into the home. The homeowner should not have to work around poorly placed lines or accept an indoor head installed in an illogical location simply because it was faster for the installer to put it there.
In Venise-en-Québec, we installed a MIDEA 28 dual-zone heat pump capable of managing two spaces separately, with an especially efficient 18,000 BTU platform, certified for cold climates and using R-454B. But the product is only part of the equation.
The other part is the work surrounding the product: sizing, choosing the two indoor capacities, head placement, line-set routing, water drainage, electrical supply, preparation of the refrigerant connections, testing, and commissioning.
This is exactly the same approach we apply to our HVAC installations in Montreal, Laval, Longueuil, on the South Shore and on the North Shore. A high-performance heat pump must be selected for the actual building, not just because a capacity or SEER2 rating looks impressive on a specification sheet.
MIDEA 28 dual-zone: what type of project is it particularly well suited for?
This 18,000 BTU configuration becomes relevant when you want to serve two zones with different needs without installing two separate outdoor compressors.
It could be a ground floor and an upper floor, an open-concept area and a primary bedroom, a house where certain rooms overheat in summer, or a renovated space that does not receive enough air from an existing system.
The option of using indoor heads with different capacities provides considerable flexibility. A small room does not need to receive the same unit as a large open-concept area. This is precisely where studying the project before installation makes a difference.
The Midea lineup also offers different types of indoor units - wall-mounted, ducted, cassette, console, and other solutions - allowing the multi-zone platform to adapt to very different residential configurations. The manufacturer presents this compatibility between ducted and ductless systems as one of the lineup's main advantages.
An HVAC installation that can be assessed as much by its specifications as by its finish
The MIDEA 28 dual-zone 18,000 BTU offers particularly strong specifications: SEER2 25.0, HSPF2 10.4, heating capacity down to -30 °C, ENERGY STAR® Cold Climate certification, R-454B refrigerant, and the ability to manage multiple zones from a single compressor.
But our photo from Venise-en-Québec highlights an equally important point: occupants live with the installation, not the brochure.
The head height, clearance around the unit, airflow direction, line-set routing, and ease of maintenance are all integral to the result.
At AirGreen, it is this combination of technical selection, careful installation, and methodical commissioning that we strive to reproduce on every job site, whether it is located in Venise-en-Québec, Montreal, Laval, Longueuil, on the North Shore, or on the South Shore.
For a dual-zone heat pump project, we can assess the load of each space, select the appropriate indoor capacities, confirm the approved Midea combination, and verify the AHRI listing as well as the applicable LogisVert financial assistance before finalizing the project.