At Pointe-des-Cascades, an elevated MIDEA28 rooftop installation designed to accommodate snow, defrosting, and an already crowded mechanical environment
This MIDEA28 wall-mounted heat pump installation in Pointe-des-Cascades has a very different outdoor configuration from a standard residential installation against a house wall. Here, the outdoor unit was installed on a flat gravel-covered roof, amid an environment where several roof elements were already present: parapets, ventilation outlets, a chimney, and other mechanical structures.
The photograph taken on site makes the main challenge immediately apparent. We could not simply place the heat pump at roof level. We therefore chose an installation on a raised metal support, with visible distribution elements beneath the structure to keep the unit elevated above the roof.
This positioning addresses several very practical needs for a heat pump intended to operate through Quebec’s four seasons: maintaining space beneath the unit, facilitating drainage during defrost cycles, reducing the risk of snow-related blockage, and allowing adequate access around the equipment.
The MIDEA28 installed here is a side-discharge heat pump. This compact design is specifically presented by MIDEA as a solution that can suit different configurations, including on a roof, deck, or balcony, when the installation is adapted to the building.
In a project like this one in Pointe-des-Cascades, the model choice is important, but how the unit is installed is just as important.
A roof is never simply “an empty space”
A photo of a heat pump installed on a roof can give the impression that there is plenty of space. In practice, the opposite is often true.
Every element already in place influences our decision:
- ventilation outlets must remain accessible;
- parapets can alter airflow;
- lines must be protected and organized;
- traffic areas used for maintenance must remain accessible;
- mechanical equipment must not interfere with one another;
- snow and ice must be anticipated;
- the roof itself must be taken into account.
For this installation Pointe-des-Cascades, we can notably see a curved metal outlet near the unit, as well as several mechanical components farther away. The heat pump was therefore positioned in an area that keeps its immediate surroundings relatively clear.
This is an important decision because an outdoor unit must be able to draw in and discharge large quantities of air.
Why did we install the MIDEA28 well above the gravel?
The support visible beneath the heat pump is one of the most important elements of this project.
When a heat pump operates in heating mode, its outdoor heat exchanger can accumulate frost. The unit periodically initiates a defrost cycle to remove this accumulation.
During this process, water drains from the unit.
In winter, this water can obviously refreeze on a cold roof. If a heat pump is installed too close to the surface, the space available beneath the unit can gradually become insufficient.
Snow is an additional factor.
A very low installation can become much more vulnerable to significant accumulation around the heat exchanger or underneath the machine.
By raising the MIDEA28, we create a much greater physical separation between the unit and the roof.
The structure visible in the photo is an integral part of the HVAC installation
The unit rests here on a metal frame on legs.
Under this structure, the photograph shows wooden pieces and load-distribution elements placed on the roof. Our goal in this type of configuration is to create a stable base while taking the roof environment and the installation's load distribution into account.
A heat pump should not be viewed as simply an object placed wherever space is available.
During operation, it contains:
- a compressor;
- a fan motor;
- changes in operating speed;
- start-up and modulation cycles;
- mechanical vibrations.
On a roof, we must therefore pay particular attention to stability and vibration control.
The goal is to avoid unnecessarily transmitting noise to the building while maintaining a structure that is sufficiently rigid to properly support the unit.
MIDEA28: a cold-climate heat pump that can operate down to -30 °C
The MIDEA28 belongs to MIDEA's premium wall-mounted series.
According to the documentation provided, this series uses R-454B refrigerant, carries the rating Cold Climate V6.1 and can operate in heating mode when the outdoor temperature drops as low as -30 °C. The range reaches up to 27.4 SEER2 in cooling and up to 13.5 HSPF2, depending on the selected combination.
These characteristics explain why preparing the outdoor installation is so important.
Installing a heat pump capable of operating at -30 °C without accounting for snow accumulation or defrosting conditions around its outdoor unit would be contradictory.
The unit’s performance and the quality of its location must go hand in hand.
Five available capacities in the MIDEA28 range
Unlike the MIDEA35, which is offered in a more limited range of capacities in the brochure provided, the MIDEA28 is offered in five sizes: 9,000, 12,000, 18,000, 24,000, and 33,000 BTU/h in cooling.
The documented combinations are as follows:
| MIDEA28 configuration | Cooling | Rated heating | SEER2 | HSPF2 IV | AHRI reference |
|---|---|---|---|---|---|
| MSEHU-H09B-2A / MO1HS-H09B-2A | 9,000 BTU/h | 12,000 BTU/h | 27,4 | 12,5 | 215471380 |
| MSEHU-H12B-2A / MO1HS-H12B-2A | 12,000 BTU/h | 12,000 BTU/h | 25,4 | 10,5 | 215471381 |
| MSEHU-H18B-2A / MO1HS-H18B-2A | 18,000 BTU/h | 18,000 BTU/h | 21,4 | 11,0 | 215471382 |
| MSEHU-H24B-2A / MO1HS-H24B-2A | 24,000 BTU/h | 29,000 BTU/h | 21,0 | 13,5 | 215471383 |
| MSEHU-H33B-2A / MO1HS-H33B-2A | 33,000 BTU/h | 36,000 BTU/h | 19,5 | 10,5 | 215471384 |
These figures clearly show why it is important to avoid referring to “the performance of the MIDEA28” as though there were only one combination. Performance, BTUs, electrical requirements, dimensions, and refrigerant lines vary depending on the selected capacity.
The site photo does not allow us to read the complete model number of the unit installed in Pointe-des-Cascades with certainty. We therefore do not assign it a specific capacity based solely on its appearance.
A properly sized heat pump is preferable to a machine selected solely according to its maximum BTU rating
When a homeowner compares heat pumps, it may be tempting to think that a higher capacity will automatically provide greater comfort.
That is not our approach at AirGreen.
Proper selection depends on several factors:
- the area actually served;
- insulation level;
- the quantity and quality of the windows;
- heat loss;
- solar exposure;
- room layout;
- air circulation;
- use of space;
- heating needs during cold periods.
A wall-mounted heat pump when properly sized, it can make better use of its modulation capacity.
MIDEA uses variable-speed technology that allows the compressor to adjust its operation to the heating and cooling demand rather than operating only through full on-and-off cycles. The manufacturer associates this technology with reduced indoor temperature variations.
A rooftop installation also affects the selection of the refrigerant lines
The routing of the lines between the indoor unit and the outdoor unit becomes even more important when a heat pump is installed on a roof.
The MIDEA28 has several requirements depending on its capacity.
For the configurations of 9,000 and 12,000 BTU/h, the liquid and gas lines are 1/4 in. and 3/8 in..
The 18,000 BTU/h uses 1/4 in. and 1/2 in..
The 24,000 BTU/h requires 3/8 in. and 5/8 in..
Finally, the 33,000 BTU/h uses 3/8 in. and 3/4 in..
This is a significant variation.
Therefore, when replacing an old heat pump, it is never enough to see that an existing line set is already in place to conclude that it can be reused.
We always check the exact model.
Up to 164 feet of piping for certain configurations
The maximum lengths also vary with capacity.
MIDEA states:
- 82 ft maximum for the 9,000 and 12,000 BTU/h versions;
- 98.4 ft for the 18,000 BTU/h version;
- 164 ft for the 24,000 and 33,000 BTU/h versions.
The maximum height difference ranges from 49.2 ft to 82 ft, depending on the combination.
These values are particularly relevant for a rooftop HVAC installation.
When the outdoor unit is several floors above the indoor unit, the actual route and elevation difference must be measured before confirming that the configuration complies with the equipment's limits.
Electrical requirements can range from 15 A to 35 A
The same principle applies to the electrical system.
The MIDEA28 uses a 208/230 V, single-phase, 60 Hz, but the outdoor unit's requirements vary significantly according to its capacity.
The documentation specifies, among other things:
- 9,000 BTU: minimum ampacity 15 A, maximum protection 15 A;
- 12,000 BTU: minimum ampacity 15 A, maximum protection 15 A;
- 18,000 BTU: minimum ampacity 19 A, maximum protection 20 A;
- 24,000 BTU: minimum ampacity 24.9 A, maximum protection 25 A;
- 33,000 BTU: minimum ampacity 34 A, maximum protection 35 A.
That is why we always check the nameplate and the exact combination of equipment before determining the circuit requirements.
BTUs are important information, but they never replace the manufacturer's electrical data.
A successful rooftop installation depends as much on mechanical details as on the performance of the MIDEA28
In the photo, the side of the heat exchanger remains accessible
This view from the back or side of the MIDEA28 shows a series of openings that allow air to circulate through the outdoor unit.
This heat exchanger must remain clear.
On a roof, various objects can gradually accumulate around equipment: leaves, debris, maintenance materials, or snow buildup.
We therefore choose the location with the future in mind.
A technician must be able to inspect the heat exchanger, reach the service panel, and move around the unit without constantly having to move obstacles.
The proximity of a ventilation outlet requires precise planning
To the right of the heat pump, we can clearly see a metal ventilation outlet already present on the roof.
This is exactly the kind of constraint we must consider before installing the support.
An outdoor unit must not be positioned arbitrarily in the middle of existing equipment.
We must maintain the necessary clearances around:
- fan;
- heat exchanger;
- technical access points;
- building exits;
- traffic areas.
The objective is for each piece of equipment to continue fulfilling its function.
The R-454B refrigerant and A2L technology
The entire MIDEA28 range presented in the brochure operates with R-454B.
The MIDEA documentation also mentions, among the features of the MIDEA35, MIDEA28, and MIDEA25 series, an A2L dispersion system as well as an A2L refrigerant leak detection sensor.
For the owner, daily operation remains simple.
For us, as HVAC professionals, the nature of the refrigerant nevertheless influences the procedures and equipment used during installation and service.
A good support must also take the actual weight of the unit into account
The different MIDEA28 units do not all weigh the same.
According to the brochure, the net weight of the outdoor unit varies from approximately 72.75 lb for the smallest configurations to 156.97 lb for the 33,000 BTU/h model.
That is a considerable difference.
A roof support must therefore be adapted to the equipment actually installed.
The stability of the system as a whole must also be considered, rather than only the metal’s capacity to support the machine’s static weight.
Future maintenance begins on the day of installation
We place great importance on the ability to carry out HVAC maintenance several years after installation.
On a roof, this issue becomes particularly important.
An installation too close to a parapet, too low, or wedged between two pieces of equipment can make service work unnecessarily difficult.
Here, the MIDEA28 remains elevated and visible from several sides.
This makes it possible to maintain more logical access for future operations such as:
- visual inspection;
- heat exchanger cleaning;
- electrical diagnosis;
- connection inspection;
- operational check;
- work on the refrigerant circuit.
The comfort features available indoors
Even though this installation is particularly noteworthy from the outdoor perspective, the MIDEA28 also offers a complete set of features inside the property.
MIDEA lists the following features, among others, for the 35, 28, and 25 series:
- ECO mode;
- Turbo;
- night mode;
- timer;
- child lock;
- function Follow Me;
- automatic cleaning;
- silent mode;
- 8°C heating;
- horizontal swing;
- vertical swing;
- smart sensor;
- humidity control;
- Wi-Fi and wired control options depending on the configuration.
The documentation also indicates up to 100 air volume adjustment levels, allowing much more precise modulation of the indoor fan than a few fixed speeds.
The sound level varies with capacity
For the outdoor unit, the brochure indicates the following maximum sound levels during high operation:
- 56 dB(A) for the 9,000 and 12,000 BTU versions;
- 59 dB(A) for the 18,000 BTU version;
- 61.5 dB(A) for the 24,000 BTU version;
- 63.5 dB(A) for the 33,000 BTU version.
On a roof, we pay extra attention to vibration transmission to the structure, since the noise perceived inside a dwelling does not depend solely on the dB(A) figure listed in the technical specifications.
The support, its stability, and the building itself also play a role.
MIDEA28 and financial assistance: verification must be done using the AHRI number
The brochure provided identifies the five MIDEA28 combinations by their AHRI numbers and classifies them in the category Cold Climate V6.1.
However, it does not provide any LogisVert financial assistance amount for this specific installation in Pointe-des-Cascades.
We therefore avoid announcing a subsidy solely because the unit bears the name MIDEA28.
To determine a heat pump’s actual eligibility and the potential applicable amount, we must verify at least:
- the exact indoor model;
- the exact outdoor model;
- the AHRI number;
- the capacity recognized by the program;
- the required certifications;
- the actual installation date;
- the criteria applicable to the building.
This is particularly important with a range containing five capacities and five different AHRI references.
Mistakes to avoid when installing a heat pump on a roof
Our project of Pointe-des-Cascades allows several errors to be highlighted that may seem minor at first but become problematic after a few seasons:
- install the heat pump too close to the roof surface;
- overlook snow accumulation;
- fail to plan for water from defrosting;
- block one side of the heat exchanger with a nearby structure;
- place the unit too close to a mechanical outlet;
- underestimate vibrations;
- select a support without knowing the unit’s actual weight;
- use refrigerant lines incompatible with the capacity;
- exceed the permitted elevation difference or piping length;
- make the service panel inaccessible;
- choose the electrical circuit based on an approximate BTU rating;
- leave a piping route unnecessarily exposed to high-traffic areas.
A good wall-mounted heat pump installation therefore never consists solely of starting up the machine.
This project in Pointe-des-Cascades illustrates our AirGreen approach
The final photograph mainly shows a MIDEA unit installed on a support in the middle of a flat roof.
But this result summarizes several technical decisions.
We had to take into account the the unit’s height, its surroundings, access to other equipment, clearance beneath the heat pump, airflow, and future maintenance.
The MIDEA28 is designed to provide heating and cooling even in harsh winter conditions. To truly benefit from these capabilities, its outdoor installation must be compatible with the reality of a Quebec roof.
This is the approach we apply in our installations in Pointe-des-Cascades, but also in our projects in wall-mounted heat pumps in Montreal, Laval, Longueuil, on the North Shore and South Shore.
Each building has its own constraints.
In a house, we may need to work around a window or terrace. In a condo, regulations and balconies influence the solution. On a roof like the one pictured here, snow, mechanical equipment, stability, and access guide our work instead.
Our role is to adapt theHVAC installation to the building rather than applying the same solution everywhere.
In Pointe-des-Cascades, this elevated installation gives the MIDEA28 a much better-suited environment for year-round use: clearance beneath the unit, side access, separation from the roof, and sufficient space around the main components.
This is precisely the kind of detail that does not appear on an energy-efficiency rating sheet but makes a tangible difference throughout the years the heat pump is in use.