In Sainte-Julie, an MIDEA35 installed in a space where the ceiling, window, and line routing dictated their own logic
Some wall-mounted heat pump seem simple when looking only at the final result. On this project carried out by AirGreen in Sainte-Julie, on the Montreal’s South Shore, the photo tells a much more technical story: the indoor unit had to be installed in a particularly challenging corner of the room, immediately next to a window and beneath a sloped ceiling junction, while the line routing was concentrated in the upper part of the wall.
It is precisely in this type of configuration that choosing the location becomes as important as choosing the equipment.
We installed a MIDEA MIDEA35 wall-mounted heat pump, a series designed for Quebec’s cold climate and using the refrigerant R-454B. The label A2L clearly visible on the side of the photographed indoor unit corresponds to the safety classification of the refrigerant used in this new generation of equipment.
The MIDEA35 is part of Midea’s ductless wall-mounted systems; the manufacturer’s documentation presents the MIDEA35, MIDEA28, MIDEA25, and MIDEA22 series as a range of ductless heat pumps intended for residential heating and cooling.
The main challenge: fitting the evaporator into a very limited wall area
In the photo of our installation in Sainte-Julie, several constraints are immediately apparent.
The unit is located near a corner of the building. A window occupies a significant portion of the adjacent wall. The ceiling does not provide a large, uniform horizontal surface above the unit. Finally, the lines run through the upper part of the room.
For a homeowner, the question may seem limited to finding a space wide enough to accommodate the unit. For us, a HVAC installation requires additional checks.
We must consider all of the following simultaneously:
- the evaporator’s physical dimensions;
- the required clearances around the unit;
- future access to the filters and internal components;
- the airflow direction;
- the refrigerant line routing;
- condensate drainage;
- the electrical communication between the units;
- the possibility of eventually carrying out a HVAC maintenance or a repair without having to dismantle building components.
The visible placement in this installation makes use of a section of wall that would otherwise have been difficult to use. In a room with a nearby window and limited available space, this approach keeps the main walls clear while positioning the wall-mounted air conditioner in the upper part of the room.
A line route that required different planning
The photo also shows the route of the lines in the area above the heat pump. This is not the classic scenario in which all the connections disappear immediately behind the evaporator and pass directly through the wall.
When the building configuration requires a different route, we must adapt the installation without compromising the unit's mechanical operation.
A wall-mounted heat pump uses two refrigerant lines, communication wiring, and a condensate drain. The bend radius, pipe diameters, total length of the refrigerant connection, and elevation difference between the indoor and outdoor units must remain within the limits specified for the installed combination.
The Midea brochure highlights one of the major advantages of a ductless system: the indoor and outdoor units can be connected without building a complete network of ventilation ducts. The documentation also presents significant options for line length and elevation difference, which then vary according to the specific model.
Why we never force existing piping to suit a new machine
When replacing an older heat pump, it may be tempting to automatically keep the existing copper lines because they are already in place.
This decision must always be technically validated.
For the MIDEA35, the line sizes change according to capacity. The 9,000 and 12,000 BTU/h version uses 1/4 in – 3/8 in, while the 18,000 BTU/h request of the 3/8 in – 5/8 in. The indicated maximum length is 82 ft for the two smaller capacities and 164 ft for the 18,000 BTU/h model.
It is a detail that can completely change the strategy for a replacement.
The A2L label visible in our photo is not a decorative detail
On the right side of the unit installed in Sainte-Julie, the pictogram associated with the category is clearly visible A2L.
The MIDEA35 operates on R-454B, and the Midea brochure also indicates the presence of a detection system linked to A2L refrigerant leaks, as well as associated dispersion functions on the applicable series.
The transition to A2L refrigerants means that work methods, tools, and procedures must be adapted to this new generation of systems.
For the homeowner, the end result remains an easy-to-use wall-mounted heat pump. For our technicians, the refrigerant characteristics are part of job-site preparation, refrigerant-line connections, leak testing, and commissioning.
A high-mounted installation must also remain accessible
A wall-mounted unit is generally installed high on a wall to promote air circulation. In this case, the limited space made precise positioning of the unit particularly important.
We must always think about what comes after installation.
The filters will need to be removed and cleaned. The heat exchanger must remain accessible. After several seasons of operation, more thorough cleaning may be recommended.
The MIDEA35 series is specifically designed with an interesting feature for this type of servicing: Midea states that the blower wheel can be removed to facilitate thorough cleaning of the inside of the unit. The series also features automatic cleaning, a quiet mode, horizontal and vertical oscillation, and precise fan-speed control.
It is therefore not enough simply to fit the unit into the available space. We must preserve the possibility of servicing it properly.
MIDEA35: the technical specifications that explain our choice for a Québec installation
Page 10 of the Midea brochure classifies the MIDEA35 as a high-end wall-mounted series designed for cold climates. It advertises heating operation down to -30 °C, an efficiency of up to 33.3 SEER2 and up to 22.0 HSPF2, with refrigerant R-454B.
These maximum values are important, but they should not be applied indiscriminately to all capacities. A common mistake when comparing heat pumps is to take the best advertised value for a series and assume that all its versions deliver exactly the same performance.
Three MIDEA35 capacities, three different performance data sheets
The documented series includes the following configurations:
| Nominal cooling capacity | Indoor model | Outdoor model | AHRI | SEER2 | HSPF2 IV |
|---|---|---|---|---|---|
| 9,000 BTU/h | MSESU-H09B-2A | MO1SS-H09B-2A | 215471386 | 33,3 | 22,0 |
| 12,000 BTU/h | MSESU-H12B-2A | MO1SS-H12B-2A | 215471387 | 29,4 | 14,5 |
| 18,000 BTU/h | MSESU-H18B-2A | MO1SS-H18B-2A | 215471388 | 25,6 | 16,2 |
The brochure lists the following nominal heating capacities, respectively: 12,000, 12,000, and 20,000 BTU/h for these three configurations.
The photo of the installation site does not show the complete model number clearly enough to determine with certainty whether the Sainte-Julie unit is the 9,000, 12,000, or 18,000 BTU/h version. We therefore prefer to present the exact specifications of the series rather than artificially assigning a capacity to the system shown in the photo.
It is the same rigor we apply when a customer sends us a photo of an old heat pump: when a nameplate is not legible, we request verification rather than guessing.
Performance that remains significant as the temperature drops
For homeowners in Sainte-Julie, Longueuil, and the South Shore, winter performance is often more decisive than efficiency on a summer day.
At -15 °C, Midea indicates a nominal heating capacity of:
- 13,500 BTU/h for the MIDEA35 9,000 BTU;
- 13,500 BTU/h for the MIDEA35 12,000 BTU;
- 22,600 BTU/h for the MIDEA35 18,000 BTU.
All three configurations have an advertised heating operating range down to -30 °C.
This information explains why we place so much emphasis on the difference between the nominal capacity stated in the product name and the heating capacity actually available at different temperatures.
For a heat pump in Montreal, Laval, Longueuil, on the North Shore or the South Shore, properly sizing the unit therefore means analyzing the building’s needs rather than simply choosing “more BTUs.”
A sound level suited to occupied rooms
The location of the indoor unit in Sainte-Julie also makes acoustic comfort relevant.
Depending on capacity, the MIDEA35 can operate at particularly low indoor sound levels. The brochure indicates approximately 19 dB(A) in silent mode for the 9,000 and 12,000 BTU versions, while the 18,000 BTU version goes down to 16 dB(A) depending on the conditions and fan setting.
The series also offers up to 100 air volume settings, allowing airflow to be adjusted more precisely rather than being limited to a few fixed speeds. Midea also provides remote control through its SmartHome environment and Wi-Fi when they are configured on the system.
The “Follow Me” mode can be useful in a room with an unusual layout
In a room where the evaporator is located very high and close to a corner, there may be a difference between the temperature measured around the unit and the temperature felt elsewhere in the occupied area.
The function “Follow Me” or “Follow Me” uses the temperature sensor built into the remote control to help the unit adjust its operation according to the temperature measured where the remote control is located.
This function obviously does not replace proper sizing or positioning, but it provides an additional tool for fine-tuning comfort.
Electrical supply: the machine’s capacity also changes the requirements
Choosing a 9,000, 12,000, or 18,000 BTU heat pump does not only change the amount of heating available.
The MIDEA35 units shown in the brochure operate at 208/230 V single-phase, 60 Hz. For the outdoor unit, the manufacturer specifies a minimum ampacity of 16 A and a maximum overcurrent protection of 20 A for the 9,000 and 12,000 BTU versions. The 18,000 BTU version requires a minimum ampacity of 24.9 A and maximum protection of 25 A.
During our installations, the electrical check is therefore part of the project. We do not choose a circuit breaker solely based on the number of BTUs: we follow the specifications prescribed for the exact equipment combination.
LogisVert: a very important detail for the 9,000 BTU MIDEA35
At the time this article was written, Hydro-Québec offers through its LogisVert a rebate of $120 per 1,000 BTU/h of heating capacity at -8 °C for a certified heat pump ENERGY STAR – Cold Climate, when all program requirements are met.
However, one current rule deserves particular attention: the outdoor unit must have a nominal cooling capacity of at least 12,000 BTU/h to be eligible.
This means that you should not look only at the “cold climate” label.
The MIDEA35 9,000 BTU, despite its excellent performance data and its cold-climate certification indicated in the documentation, falls below this nominal minimum of 12,000 BTU/h. For the 12,000 or 18,000 BTU, eligibility and the rebate amount must be confirmed using the exact combination of models, the AHRI number, the capacity at -8 °C, the installation date, and the LogisVert terms applicable to the project.
This is a particularly important distinction when two quotes wall-mounted heat pumps are compared solely based on the post-rebate price.
The mistakes this Sainte-Julie installation reminds us to avoid
This installation is a good example of the checks we perform before and during a project:
- Do not choose the location based solely on aesthetics. In an area near a window, corner, or unusual ceiling, you must also consider airflow, connections, and service access.
- Do not assume that all MIDEA35 units have the same lines. An 18,000 BTU MIDEA35 does not use the same line-set diameters as the 9,000 and 12,000 BTU versions.
- Do not size solely based on square footage. The windows, insulation, room layout, floors, and heat loss all change the requirements.
- Do not confuse minimum operating temperature with available capacity. A heat pump capable of operating at -30 °C does not necessarily provide its full rated capacity at that temperature.
- Do not assume that certification automatically entitles you to a rebate. The LogisVert rules include, among other things, a minimum rated capacity and several conditions concerning the equipment, the home, and the installation.
What the homeowner gets after a well-planned installation
Once commissioning is complete, all the work hidden behind the project should translate into something very simple: a room that heats properly in winter, cools efficiently in summer, and maintains a more stable temperature.
Midea’s variable-speed technology allows the compressor to adjust its operation to demand rather than relying solely on complete on-off cycles. The manufacturer associates this modulation with a more stable indoor temperature and better-controlled energy consumption.
For us, this installation in Sainte-Julie primarily illustrates a real-world reality: even a heat pump with excellent technical specifications must be adapted to the building in which it is installed.
Here, the visible challenge was space. The ceiling, wall corner, window, and routing of the lines left little room for improvisation. Our job was therefore to integrate the MIDEA35 to this particular geometry while retaining the elements essential to its operation and maintenance.
This is the same method we apply to heat pump installations heat pumps in Montreal, Laval, Longueuil, on the North Shore, and on the South Shore : inspect the equipment, understand the building, plan the mechanical and electrical routes, then install the system according to the site’s actual constraints.
The Midea brochure also presents, for residential applications, an advertised warranty program of up to 12 years on the compressor, 12 years on parts, and 10 years on labor, subject to the terms applicable to the product and the warranty program.
A HVAC installation successful installation is therefore not simply a heat pump mounted on the wall. It is the complete combination of sizing, placement, piping, electrical work, drainage, commissioning, and future access for maintenance. On this Sainte-Julie project, the room’s very tight configuration made each of these decisions particularly important.