In Saint-Denis-sur-Richelieu, the challenge was as much the outdoor location as winter performance
A wall-mounted heat pump installation successful installation is never simply a matter of mounting an indoor unit and placing a compressor outdoors. At Saint-Denis-sur-Richelieu, we worked on a masonry building where the limited space at the foundation level required careful consideration of the outdoor unit's position, its height, future maintenance access, and how to limit vibrations transmitted to the structure.
The result is immediately visible: the MIDEA MIDEA35 wall-mounted heat pump is installed on a metal wall bracket, above ground level, between two basement openings protected by metal grilles. The electrical supply is accessible on the adjacent wall, and the connections were arranged compactly around the unit. In an area like Saint-Denis-sur-Richelieu, where snow, freezing, thawing, and water accumulation are part of the realities of an outdoor installation, this location choice is genuinely important.
This project illustrates exactly how we work at AirGreen: we first analyze the building, then adapt theHVAC installation to the available space rather than imposing a standard configuration.
A narrow outdoor space that required a carefully considered installation
The jobsite photograph shows several constraints that could easily have led to a less practical installation.
We have a stuccoed foundation topped by a brick wall, two basement windows on either side of the available location, and relatively little free ground space. The heat pump therefore could not simply be placed anywhere on a pad.
The wall bracket becomes particularly useful here.
It notably allows us to:
- keep the outdoor unit above the ground and common snow accumulations;
- preserve the space in front of the basement windows;
- facilitate the drainage of water produced during defrost cycles;
- keep the equipment accessible for future HVAC maintenance;
- avoid having a ground-level pad unnecessarily occupy an already restricted passage;
- reduce the risk of contact with the ground, leaves, and certain debris accumulating around the foundation.
This installation also shows isolators beneath the outdoor unit's feet. This small detail matters greatly. A heat pump equipped with a variable-speed compressor operates for long periods at different speeds. We therefore seek to prevent the unit's normal vibrations from being transmitted directly to the bracket and then to the building wall.
Why we avoid choosing the location based solely on pipe length
When a homeowner compares quotes thermopompes muraleswall-mounted heat pumps
, the position of the outdoor compressor may sometimes seem secondary. In the field, however, it affects the installation’s service life, perceived noise, maintenance, and even the ease of servicing several years later. Saint-Denis-sur-RichelieuIn the photographed case at
, we had to work around the existing openings and the foundation wall. The compressor is positioned to preserve a work area around its connections and service panel.
Midea’s documentation specifically highlights the flexibility of ductless systems. Depending on the product line, the refrigerant lines can allow the indoor unit to be installed at a distance, and the side-discharge outdoor unit is designed for compact integration on a bracket or pad.
This flexibility does not mean, however, that excessive piping length is desirable. At AirGreen, we seek a logical route: flexible enough to position the unit correctly, but without adding metres of copper simply because the manufacturer allows a long maximum length.
A MIDEA35 designed for Quebec’s temperature swings MIDEA35 The is part of Midea’s high-end wall-mounted series. The supplied brochure presents it asan extreme heat pump using R-454B refrigerant -30 °C, capable of operating in heating mode down to . The series is available in nominal capacities of.
9,000, 12,000, and 18,000 BTU/h This is especially relevant in Saint-Denis-sur-Richelieu, but also for our installations inMontreal, Laval, Longueuil, on the North Shore and the South Shore
. A heat pump that performs very well in September is not necessarily the one we want to see outside a house on a January night.
| With the MIDEA35, the published technical data is particularly interesting: | MIDEA35 model | Nominal cooling | Nominal heating | SEER2 | HSPF2 IV |
|---|---|---|---|---|---|
| AHRI | 9,000 BTU/h | 12,000 BTU/h | 33,3 | 22,0 | 215471386 |
| MSESU/MO1SS-H12B-2A | 12,000 BTU/h | 12,000 BTU/h | 29,4 | 14,5 | 215471387 |
| MSESU/MO1SS-H18B-2A | 18,000 BTU/h | 20,000 BTU/h | 25,6 | 16,2 | 215471388 |
These values come from the MIDEA35 series documentation. It also indicates a nominal heating capacity at -15°C of 13,500 BTU/h for the 9,000 and 12,000 BTU versions, and 22,600 BTU/h for the 18,000 BTU version.
An important clarification about the capacity actually installed
The project file identifies the MIDEA35, but the exact BTU capacity is not indicated in the information provided. We therefore prefer not to turn an assumption into a technical specification.
This is all the more important because the versions The 9,000 and 12,000 BTU MIDEA35 models use an outdoor unit with the same dimensions, approximately 35.04 inches wide, 13.46 inches deep, and 26.50 inches high. A photograph of the compressor therefore cannot reliably distinguish between these two capacities. The 18,000 BTU version is larger.
That is precisely why we always verify the model number and AHRI number based on the project documents rather than estimating capacity from the appearance of the equipment.
R-454B: an installation that requires compliance with the new work methods
The MIDEA35 operates with R-454B, an A2L refrigerant. This changes certain design and service details compared with older generations of heat pumps.
Midea’s documentation notably indicates the presence of components related to A2L refrigerant leak detection as well as its dispersion system. The MIDEA35 series also includes features such as humidity control, quiet mode, automatic cleaning, horizontal and vertical swing, ECO mode, and various control options.
For us, switching to R-454B does not simply mean listing a new type of refrigerant on the invoice. Installation practices, refrigeration connections, evacuation, testing, and commissioning must be carried out according to the equipment actually installed and the applicable guidelines.
Connections that must exactly match the selected capacity
A detail often overlooked when replacing a heat pump is the diameter of the existing copper lines.
For the MIDEA35, the documentation states:
9,000 and 12,000 BTU:
1/4 in. for the liquid line and 3/8 in. for the gas line.
18,000 BTU:
3/8 in. for the liquid line and 5/8 in. for the gas line.
The published maximum lengths also differ: approximately 82 ft for the 9,000 and 12,000 BTU versions and 164 ft for the 18,000 BTU version.
That is why an “equipment-for-equipment” replacement must always begin with a verification of the copper lines. An old wall-mounted air conditioner may appear visually compatible even though its lines do not meet the requirements of the new system.
At AirGreen, we prefer to resolve this type of issue before installation rather than create a compromise that could affect compressor reliability.
An accessible and organized electrical installation
To the right of the outdoor unit visible in the photo, the electrical device installed on the foundation can be seen. Organizing this area is important to allow the heat pump to be electrically isolated during maintenance or repair.
The MIDEA35 series operates at 208/230 V single-phase, 60 Hz. Depending on the capacity, the brochure indicates a minimum allowable ampacity of 16 A for the 9,000 and 12,000 BTU models and 24.9 A for the 18,000 BTU, with maximum protection of 20 A or 25 A depending on the model.
These are parameters we never replace with an estimate based on the old heat pump. The exact model determines the required electrical protection.
Wall mounting: advantageous, but only when properly executed
Mounting the unit on the foundation is particularly relevant in several Quebec installations, but this method requires more than a pair of brackets.
We must consider the support’s structural capacity, the quality of the anchors, vibration, ground clearance, the space available around the outdoor heat exchanger, and how defrost water will be drained.
The photograph of our installation in Saint-Denis-sur-Richelieu shows precisely a configuration where the support keeps the heat pump off the ground while using space that would have been difficult to utilize with a large base.
In a narrow yard Montreal, an alley Longueuil, a duplex Laval or a South Shore, a few inches can completely change the best possible configuration.
Modulation that avoids harsh on-off operation
The other advantage of the MIDEA35 lies inside the machine. Midea uses variable-speed technology: the compressor adjusts its operation to thermal demand rather than operating only at full capacity before shutting down completely.
The documentation explains that this modulation reduces temperature fluctuations and provides a more stable indoor temperature. It states up to 33.3 SEER2 for the series and up to 22.0 HSPF2, depending on the selected combination.
For a homeowner, the practical consequence is important. A properly sized heat pump can maintain the temperature more consistently without multiplying uncomfortable fluctuations.
This is also why heat pump sizing remains essential. Automatically installing the largest model available is not an improvement. Excess capacity can lead to less favorable cycles, less effective humidity management in summer, and less consistent comfort.
Sound level matters particularly near windows
On this project, the outdoor unit is located between two basement windows. Choosing suitable equipment and a suitable location is therefore even more important.
According to the MIDEA35 brochure, the published outdoor sound level is 57 dB(A) for the 9,000 and 12,000 BTU models and 61.5 dB(A) for the 18,000 BTU model. Indoors, some quiet speeds drop to approximately 19 dB(A) for the 9,000 and 12,000 BTU models, and up to 16 dB(A) for the 18,000 BTU model.
The manufacturer’s figures are only part of the equation. Poor fastening or a resonating support can make a good heat pump unpleasant. That is why we pay as much attention to the installation mechanics as we do to the technical specifications.
A wall-mounted heat pump that is easy to control every day
The MIDEA35 offers an extensive range of settings designed for everyday comfort: adjustable fan speeds, night and quiet modes, a “Follow Me” function, timer, air oscillation, 8°C hold heating, automatic cleaning, and smart control options.
The brochure also indicates that the SmartHome app and Wi-Fi allow, depending on the configuration, remote control of the system. It mentions up to 100 airflow adjustment levels, allowing for more gradual adjustment than simply choosing between a few fixed speeds.
In a residence occupied year-round, this level of control is more useful than a large number of rarely used features: it mainly helps adapt airflow and temperature to the room’s actual use.
LogisVert subsidy: the AHRI number must be verified before announcing an amount
The question of the heat pump subsidy comes up almost systematically in our quotes.
For the MIDEA35, the published AHRI numbers are 215471386, 215471387 and 215471388, depending on the capacity. These references are essential for confirming the exact equipment and checking the applicable programs.
Hydro-Québec specifies that, for heat pumps installed as of November 26, 2025the equipment must notably be ENERGY STAR certified to qualify for the LogisVert program, and that the lists and amounts may change.
Since the exact capacity of the MIDEA35 installed on this job is not provided here, we are deliberately not publishing any subsidy amount associated with this installation. At AirGreen, we verify the the exact indoor model, outdoor model, and AHRI number before presenting a financial incentive as applicable.
This is a simple precaution that prevents choosing a heat pump based on a subsidy that ultimately does not correspond to the combination actually installed.
This project sums up our AirGreen approach to durable HVAC installation in Quebec
We are already thinking about the next winter and the next maintenance visit
At the end of an installation, our goal is not simply for the heat pump to start. We want the technician who returns several years from now to still be able to work properly around the unit.
For this project in Saint-Denis-sur-RichelieuThe elevated position, side access to the connections, and the nearby electrical device create a well-organized installation in a space that is nevertheless limited.
Snow and ice are also taken into account. In heating mode, an outdoor heat pump periodically enters defrost mode. Water may then drain beneath the unit. A unit installed too close to the ground can eventually become surrounded by ice during the winter, particularly when an initial layer of water freezes before the next cycle.
The clearance beneath the unit shown here provides more space to deal with this winter reality.
Errors This Installation Helps Prevent
Many of the problems we encounter during service calls stem less from the heat pump itself than from decisions made at the time of installation.
A compressor installed too low may be exposed to snow accumulation. An outdoor unit placed too close to an obstacle becomes difficult to maintain. A support without vibration isolation may transmit more noise to the building. An incompatible copper diameter may compromise operation. An electrical protection selected based on the old unit may not meet the requirements of the new model.
Finally, selecting a capacity based solely on the home's total area can lead to improper sizing. The building's orientation, insulation, windows, room layout, floors, and the way air circulates must also be considered.
It is this combination of details that distinguishes a simple installation from a truly professional wall-mounted heat pump installation.
A warranty that must also be read carefully
The Midea brochure states that, for residential use, there is a 12-year limited warranty on the compressor, 12 years on parts, and 10 years on labor, subject to the terms applicable to the warranty program.
As with a rebate, we always recommend keeping the invoice, model numbers, serial number, and registration documents. A generous warranty is only truly useful when the equipment is properly identified and the necessary conditions have been met.
An approach we apply in Saint-Denis-sur-Richelieu as well as throughout Greater Montreal
This installation of the MIDEA35 in Saint-Denis-sur-Richelieu clearly shows why two projects using the same heat pump may require completely different solutions.
Here, the central issue was integrating the outdoor unit onto a foundation with several openings and little ground space. On a house in the North Shore, the challenge may instead be a terrace. On the Montreal, we regularly work in narrow yards and passageways. In Laval, a project may require a long refrigerant line to keep the façade clean. In Longueuil or elsewhere on the South Shore, we often have to reconcile site access, neighboring properties, snow, and existing architecture.
Our job is to bring all these constraints together in a coherent installation.
For the MIDEA35, this means enjoying a wall-mounted heat pump capable of heating down to -30 °C, using the R-454B, offering excellent seasonal efficiency and several available capacities, while giving as much attention to the support, electrical system, copper piping, drainage, and accessibility as to the machine itself.
It is this attention to visible and invisible details that allows a HVAC installation to remain clean, practical, and easy to maintain long after our team has left.