An installation in Calixa-Lavallée where outdoor positioning matters just as much as the heat pump’s performance
In Calixa-Lavallée, in Montérégie, this installation of a MIDEA MIDEA35 wall-mounted heat pump clearly illustrates a reality we regularly encounter at AirGreen: even when a heat pump is technically highly efficient, its long-term performance also depends on an outdoor installation suited to the building, Quebec’s climate, and the actual constraints of the site.
On this project, the MIDEA outdoor unit is installed against the foundation of a brick house, near an exterior door and a staircase. The available space was therefore not simply a large, unobstructed façade where the equipment could be placed anywhere. We had to preserve a functional passageway, avoid obstructing the access area, keep the unit sufficiently elevated above the ground, and create a solid installation that would remain practical for future maintenance.
The visible result in the photo is highly representative of our approach: the outdoor unit is elevated on a metal wall bracket, secured to the structural portion of the foundation. It is therefore positioned above the ground, vegetation, and normal accumulations of snow or debris. To the right of the unit, the electrical disconnect remains accessible, while the equipment connections are grouped compactly on the building side.
This type of detail may seem secondary when comparing only the prices of several wall-mounted heat pumps, but it directly affects ease of maintenance, equipment stability, and its ability to operate properly during our winters.
The MIDEA35: a wall-mounted heat pump designed for low-temperature heating
The MIDEA35 belongs to Midea’s premium wall-mounted series. The manufacturer’s technical documentation classifies it among its heat pumps capable of operating in heating mode down to -30 °C, with the refrigerant R-454B, cold-climate certification, and outputs of up to 33.3 SEER2 in cooling and 22.0 HSPF2 depending on the selected capacity.
For a residence in Calixa-Lavallée, this operating range is particularly relevant. A heat pump is not chosen solely to provide cooling for a few weeks during the summer. In a properly designed HVAC system, it must also be capable of making a meaningful contribution to heating when temperatures drop in December, January, and February.
The range MIDEA35 presented in the brochure includes three main capacities:
- 9,000 BTU : MSESU-H09B-2A / MO1SS-H09B-2A units, AHRI 215471386, up to 33.3 SEER2 and 22.0 HSPF2;
- 12,000 BTU : MSESU-H12B-2A / MO1SS-H12B-2A units, AHRI 215471387, 29.4 SEER2 and 14.5 HSPF2;
- 18,000 BTU : MSESU-H18B-2A / MO1SS-H18B-2A units, AHRI 215471388, 25.6 SEER2 and 16.2 HSPF2.
Because the unit’s nameplate was not legible enough in the project photo to confirm the exact installed capacity without ambiguity, we prefer to present the series specifications rather than arbitrarily assign a BTU rating to this installation.
This is also a useful lesson for any homeowner comparing quotes: the name MIDEA35 alone is not sufficient to determine the sizingYou must always verify the indoor model number, the outdoor model number, and the AHRI reference corresponding to the complete system.
A wall-mounted bracket that addresses a very practical site constraint
In this installation in Calixa-LavalléeThe outdoor unit was not placed directly on the ground. Instead, we used a metal wall-mounted structure that keeps the compressor at a safe height.
This method offers several advantages in a Quebec installation.
First, it reduces the unit’s base exposure to water, soil, leaves, and vegetation. Then, during winter, it helps preserve clearance beneath the equipment as snow accumulates.
A heat pump in heating mode must regularly perform defrost cycles. Water may then flow beneath the outdoor unit. If it is installed too low or in a poorly drained location, this water can freeze and gradually form an accumulation of ice around the unit.
In this case, the height of the bracket also maintains a clear separation between the heat pump and the small planted area at the base of the foundation.
An installation designed around the door and staircase
The photo also shows an important detail: the unit is located immediately next to a staircase and an exterior door.
We therefore need to consider not only the heat pump’s location, but also how the building is used on a daily basis.
A poorly positioned unit could encroach on the passageway, make the stairs uncomfortable to use, complicate snow removal, or direct the fan discharge into an area where occupants are constantly moving.
Here, the format is side discharge of the Midea outdoor unit makes it well suited to installation along a wall. The manufacturer’s documentation specifically highlights the compact design of these units and their ability to be installed on a base or bracket.
This is an important practical difference between a ductless wall-mounted heat pump and some much larger central systems.
The technical details we check before installation
A good project for a wall-mounted heat pump in Calixa-Lavallée is never simply a matter of mounting two units and turning them on.
We need to check the sizing, the distance between the units, the refrigerant line routing, the electrical supply, condensate drainage, clearances around the compressor, and the strength of the mounting point.
For the MIDEA35 series, the requirements change with capacity. The 9,000 and 12,000 BTU versions use refrigerant lines measuring 1/4 in and 3/8 in, while the 18,000 BTU version uses 3/8 in and 5/8 in. The maximum lengths indicated are 82 ft for the 9,000 and 12,000 BTU models, respectively, and 164 ft for the 18,000 BTU model.
Electrical requirements also vary. According to Midea documentation, the minimum allowable ampacity of the outdoor unit is 16 A for the 9,000 and 12,000 BTU versions, with maximum overcurrent protection of 20 A, while the 18,000 BTU model requires 24.9 A with maximum overcurrent protection of 25 A.
These figures explain why we check the electrical panel and the available circuit before confirming an installation.
A highly efficient heat pump does not need to operate in an all-or-nothing manner
Variable-speed technology is another important advantage of this family of systems.
Rather than operating only at full capacity and then shutting down completely, the compressor can adjust its operation according to the room’s heating and cooling needs. Midea states that this modulation helps reduce temperature fluctuations and maintain more consistent comfort.
In a residence, this difference is most noticeable during periods when demand is moderate. The goal is not for the heat pump to start abruptly every few minutes, but to provide precisely the amount of heating or cooling required.
A properly sized unit can therefore run longer at a reduced output, which generally promotes a more even indoor temperature.
Indoor quiet is part of comfort
For many customers in Montreal, Laval, Longueuil, the North Shore, and the South Shore, the noise from a wall-mounted heat pump becomes a criterion as important as its energy efficiency, particularly when the indoor unit is installed in a bedroom or living space.
Depending on the MIDEA35 capacity, the indoor sound level can drop to approximately 19 dB(A) on the 9,000 and 12,000 BTU models and up to 16 dB(A) on the 18,000 BTU model depending on the operating mode. The published outdoor sound levels are 57 dB(A) for the 9,000 and 12,000 BTU versions and 61.5 dB(A) for the 18,000 BTU model.
Location nevertheless remains essential. Even a relatively quiet compressor can become disruptive if it is installed against a structure that amplifies vibrations or immediately beside a sensitive window.
That is why we place as much importance on the mounting method as on the model itself.
What this MIDEA35 installation teaches before choosing a wall-mounted heat pump in Quebec
The number of BTUs must be determined by the building, not by an approximate rule
A common mistake is to choose a heat pump based solely on the home's floor area.
Two homes with exactly the same floor area may require different capacities because of their insulation, orientation, number of windows, ceiling height, room layout, and heat loss.
An oversized heat pump is not automatically superior. In cooling mode, it can reach the requested temperature quickly without having enough time to dehumidify properly. An undersized heat pump, on the other hand, may run continuously without reaching the desired comfort level during the most demanding periods.
At AirGreen, we therefore seek to select the capacity that is truly suitable for the home before focusing on the maximum figures advertised in a brochure.
Performance at -15°C provides more useful information than nominal BTU alone
The MIDEA35 series is noteworthy because its documentation also provides low-temperature heating data.
At -15°CMidea indicates a nominal heating capacity of 13,500 BTU/h for the 9,000 and 12,000 BTU configurations and 22,600 BTU/h for the 18,000 BTU model.
This point is important in Quebec.
A unit described as “12,000 BTU” generally refers to its nominal cooling capacity. This does not mean that it will produce exactly 12,000 BTU of heating at all outdoor temperatures.
To properly compare several wall-mounted heat pumps, so we evaluate performance at different temperatures rather than looking only at the number included in the product name.
R-454B requires installation suited to A2L equipment
The MIDEA35 uses R-454B refrigerant. The brochure also associates the series with a detection and dispersion system designed for A2L refrigerants.
For the homeowner, this mainly means that installation must be carried out using methods, tools, and procedures compatible with this new generation of refrigerants.
The transition to A2L refrigerants underscores the importance of working with HVAC professionals who understand current requirements, rather than treating a modern heat pump exactly like an older R-410A unit.
Practical features beyond heating and cooling
The MIDEA35 offers several features designed for everyday comfort: Wi-Fi control, sleep mode, timer, “Follow Me” function, fan adjustment from 1% to 100%, horizontal and vertical swing, automatic cleaning, quiet mode, 8°C standby heating, and an optional wired controller.
The smart sensor available on the series can also help manage comfort and energy use. Midea’s documentation specifically describes a function that allows the system to adjust its operation based on room occupancy.
Another interesting detail forHVAC maintenance : the design includes a removable indoor blower wheel to facilitate more thorough cleaning.
For us, this is particularly relevant because service accessibility directly affects the quality of the cleaning that can be carried out several years after installation.
A ductless installation limits the work required inside the building
A wall-mounted heat pump is connected to its outdoor unit by the refrigerant lines, communication cables, and drainage required by the system. There is therefore no need to install a complete air-duct network throughout the house.
Midea indicates that only a small wall opening is needed to connect the units and presents this architecture as a flexible solution for bedrooms, offices, garages, renovations, and spaces with temperature variations.
This flexibility explains the popularity of wall-mounted heat pumps in Montreal and Greater Montreal, where we often work in existing buildings for which adding ductwork would be costly, complicated, or simply impossible.
LogisVert rebates must be verified using the exact AHRI number
The rebate question deserves particular attention.
Hydro-Québec currently indicates that heat pumps installed since November 26, 2025 must be certified ENERGY STAR to be eligible for the LogisVert program. For an eligible cold-climate heat pump, the program currently provides assistance calculated at $120 per 1,000 BTU/h of heating capacity at -8 °C, when all program conditions are met.
That is precisely why the complete system’s AHRI reference number and not simply the name “MIDEA35.”
For reference, the MIDEA35 configuration 12,000 BTU, AHRI 215471387, is listed with a heating capacity of 11,000 BTU/h at -8 °C and a displayed LogisVert rebate of 1 320 $. The configuration 18,000 BTU, AHRI 215471388, is listed at 19,300 BTU/h at -8 °C, with a displayed rebate of 2 316 $.
The 9,000 BTU version, although advertised as ENERGY STAR and cold-climate rated, is currently listed with a provincial rebate of $0 on our product page.
Because programs and criteria may change, we always verify eligibility based on the actual installation date, the building, and the AHRI number selected before presenting an amount as final.
A clean installation should also make the next maintenance visit easier
The installation visible in Calixa-Lavallée has an advantage that becomes most noticeable a few years later: the unit remains accessible.
The technician can reach the compressor without having to dismantle a deck or work in a completely obstructed space. The electrical disconnect is nearby, and the unit is elevated off the ground.
During future heat pump maintenance, cleaning, or diagnostic, this accessibility can make a significant difference.
We therefore encourage homeowners not to evaluate an installation solely by its appearance on the day the work is completed. It is also important to consider how a refrigeration technician will be able to access the unit five or ten years from now.
The mistakes we systematically strive to avoid
On our installations of wall-mounted heat pumps in Montreal, Laval, Longueuil, on the South Shore, and on the North Shore, several problems can be avoided as early as the planning stage: a compressor installed too close to the ground, a blocked passageway, inadequate electrical supply, incorrectly sized lines, a poorly positioned indoor unit, or a capacity chosen solely based on floor area.
In the Calixa-Lavallée project, the wall bracket, the unit’s height, and its placement along the foundation provide a concrete example of preparation before installation.
Once the system has been selected, our job is to ensure that the installation quality matches that of the equipment.
A warranty that also deserves to be verified at the time of purchase
The Midea brochure states that, for residential applications, limited warranties may cover up to 12 years on the compressor, 12 years on parts, and 10 years on labor, according to the applicable terms.
As with subsidies, we recommend confirming the specific conditions applicable to the system purchased, particularly registration requirements and exclusions.
A heat pump represents an investment lasting several years. Choosing a contractor must therefore take into account not only the initial installation, but also the availability of after-sales service and parts.
Our AirGreen approach in Calixa-Lavallée and throughout Greater Montreal
This installation of a MIDEA MIDEA35 wall-mounted heat pump in Calixa-Lavallée best summarizes how we work: analyze the building, select an appropriate configuration, consider the positioning before drilling, ensure stable mounting, and maintain practical access to the equipment.
We apply this same approach to our HVAC in Montreal, Laval, Longueuil, the North Shore, the South Shore, and Montérégie.
For a homeowner currently comparing several heat pumps, our advice is simple: look beyond the price and the number of BTUs listed on the first line of the quote. Check the AHRI numberheating capacity in cold weather, SEER2, HSPF2, electrical requirements, refrigerant line dimensions, LogisVert eligibility, and above all how the equipment will actually be installed on your building.
The MIDEA35 offers particularly interesting technical features for Quebec’s climate. However, this Calixa-Lavallée installation shows that a good heat pump only reaches its full potential when accompanied by a Thoughtful, accessible, and site-appropriate HVAC installation.