Installation of a MIDEA MIDEA35 wall-mounted heat pump in Hudson, Montérégie
In Hudson, AirGreen installs a MIDEA35 wall-mounted heat pump between a staircase and a balcony: an elevated wall bracket, a discreet line-set cover, R-454B, and heating down to -30 °C in an HVAC installation designed for the available space.
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The unit’s data sheet
The range as published on airgreen.ca: pick a size to see its capacity in deep cold.
| Size | Heating at −8 °C | Heating at −15 °C | Coldest certified point | COP at −15 °C | SEER | HSPF | Indicative LogisVert aid |
|---|---|---|---|---|---|---|---|
| Midea Série 35 9 000 | 11,000 | 13,500 | −30 °C: 7,500 | 2.0 | 33.3 | 14.6 | – |
| Midea Série 35 12 000 | 11,000 | 13,500 | −30 °C: 7,500 | 2.0 | 29.4 | 12.7 | $1,320 |
| Midea Série 35 18 000 | 19,300 | 22,600 | −30 °C: 11,900 | 2.34 | 25.6 | 16.2 | $2,316 |
According to NEEP, its certified maximum capacity at −30 °C (−22 °F) is 7,500 BTU/h, 83% of its nominal 9,000 BTU size.
At 8 °C, its certified maximum capacity reaches 17,200 BTU/h, 91% more than its nominal 9,000 BTU size.
According to NEEP, its certified heating capacity at −15 °C (5 °F) is 13,500 BTU/h, 150% of its nominal 9,000 BTU size. Its COP there is 2.00.
According to NEEP, its certified maximum capacity at −30 °C (−22 °F) is 7,500 BTU/h, 62% of its nominal 12,000 BTU size.
At 8 °C, its certified maximum capacity reaches 17,200 BTU/h, 43% more than its nominal 12,000 BTU size.
According to NEEP, its certified heating capacity at −15 °C (5 °F) is 13,500 BTU/h, 112% of its nominal 12,000 BTU size. Its COP there is 2.00.
According to NEEP, its COP at −15 °C is 2.34: the highest of the Série 35 line, which ranges from 2.00 to 2.00 at that temperature.
According to NEEP, its certified maximum capacity at −30 °C (−22 °F) is 11,900 BTU/h, 66% of its nominal 18,000 BTU size.
At 8 °C, its certified maximum capacity reaches 29,700 BTU/h, 65% more than its nominal 18,000 BTU size.
Data read live from the airgreen.ca page of each size (NEEP / AHRI certified performance). When the title names the installed size, it is highlighted; otherwise the whole range is shown. The aid shown is today’s, using Hydro-Québec’s rule ($120 per 1,000 BTU/h at −8 °C); amounts quoted in the article date from its publication. Only Hydro-Québec confirms the assistance granted.A dash in the aid column: amount to be confirmed for this model.
The article, chapter by chapter
An MIDEA35 installation in a restricted outdoor space between a metal staircase, balcony, and brick wall
This MIDEA MIDEA35 wall-mounted heat pump installation in Hudson illustrates a reality we regularly encounter at AirGreen: the best location for an outdoor unit is not always a large, completely unobstructed space. On existing buildings, we often have to work around staircases, balconies, windows, masonry walls, passages used by occupants, and various architectural constraints already in place.
In the photo from this job in Hudson, the Midea outdoor unit is installed in a relatively narrow space, between an outdoor metal staircase on the left and a balcony structure with a guardrail on the right. Behind the unit is a wall made up of a foundation section and a red brick façade.
The location therefore had to account for several factors simultaneously: airflow in front of the fan, securing the unit, protection against snow, clearance for maintenance, and the routing of the refrigerant lines.
The result is a compact installation in which the outdoor unit is raised and secured on wall brackets, rather than placing it directly on the ground.
Turning a space constraint into a functional installation
The image immediately shows the project's main challenge.
The Midea unit had to fit into a sort of outdoor passage bordered by permanent structures. On the left, the steps and stringers of the metal staircase descend directly beside the machine. On the right, the balcony structure also reduces the available space.
In this type of configuration, we cannot simply place the condenser wherever seems most convenient.
We need to check:
- clearance in front of the fan;
- the space required for air intake;
- the ability to open the service panels;
- accessibility of the refrigerant connections;
- the route for the electrical supply;
- protection of the unit against impacts;
- potential snow accumulation;
- water drainage during defrost cycles.
This consideration is essential because a wall-mounted heat pump must be able to operate properly for many years in this environment, rather than merely look satisfactory on the day of installation.
Why did we install the outdoor unit on wall brackets?
At our Hudson job site, the Midea condenser is supported by two metal brackets secured to the structure.
This solution keeps the underside of the unit clear.
For a heat pump used for heating in Quebec, this point is particularly important. During winter, the outdoor unit may run defrost cycles. The moisture and frost accumulated on the heat exchanger are then discharged as water.
If the outdoor unit is positioned too close to the ground, this water can gradually freeze beneath the unit. Accumulated snow can also reduce the available clearance.
The elevation therefore helps better prepare the installation for the winter conditions of Hudson and the Montérégie region.
It also offers a practical advantage in this specific location: the unit remains separated from the uneven ground beneath the staircase and maintains a stable position.
The existing wall required a neat route for the lines
Another visible element in the photograph is the brown vertical line set cover installed against the brick wall.
Choosing a color close to that of the masonry makes the refrigerant line set much less visually prominent than a white cover on a red façade.
This line set cover protects, in particular, the components connecting the indoor unit to the outdoor unit. In a ductless wall-mounted installation, this route generally includes insulated refrigerant lines as well as the wiring or drainage components required by the configuration.
For this project, we routed it vertically so that it would remain compact and not unnecessarily cross the entire façade.
This is a detail that matters greatly in existing buildings. A good HVAC installation is not only about achieving proper mechanical operation: it must also avoid adding a series of disorganized lines to the building.
Why the fan had to remain completely unobstructed
The large round fan visible at the front of the outdoor unit must be able to move a significant amount of air.
In both cooling and heating mode, the outdoor heat exchanger relies on this airflow to transfer heat efficiently.
In the limited space visible at our Hudson job site, we therefore had to ensure that the staircase or balcony would not be directly in front of the air outlet.
The condenser was oriented toward the open area between the two structures.
This may seem obvious once installation is complete, but the location of a heat pump must be determined before the final connections are made. A unit placed too far beneath a structure or too close to an obstacle can encourage recirculation of the air it has just discharged.
The result may then be reduced performance, especially during the most demanding outdoor temperatures.
A MIDEA35 suited to cold-weather heating
The MIDEA35 is presented in the manufacturer's documentation as a high-end ductless heat pump designed for extreme cold conditions.
Midea indicates heating operation down to -30 °C, the use of R-454B refrigerant, as well as a certification Cold Climate V6.1 for the combinations in this range. Depending on the capacity, efficiency can reach 33.3 SEER2 and 22.0 HSPF2.
For a residence in Hudson, these characteristics are much more important than simple summer cooling efficiency.
A heat pump installed in Quebec must be evaluated over its entire year of use: hot and humid days in July, cool autumn nights, freezing periods, and episodes of winter cold.
Three different capacities in the MIDEA35 family
The technical brochure presents three main MIDEA35 combinations.
MIDEA35 9,000 BTU
The combination MSESU-H09B-2A / MO1SS-H09B-2A, AHRI number 215471386, has a nominal capacity of 9,000 BTU/h in cooling and 12,000 BTU/h in heating.
Its published efficiency rating reaches 33.3 SEER2.
MIDEA35 12,000 BTU
The combination MSESU-H12B-2A / MO1SS-H12B-2A, AHRI number 215471387, provides 12,000 BTU/h nominally in both cooling and heating.
Its efficiency rating is 29.4 SEER2.
MIDEA35 18,000 BTU
The combination MSESU-H18B-2A / MO1SS-H18B-2A, AHRI reference 215471388, offers 18,000 BTU/h nominally in cooling and 20,000 BTU/h in heating, with an efficiency rating of 25.6 SEER2.
The project photograph clearly identifies the outdoor unit as a Midea unit, but it does not allow us to read the rating plate with sufficient certainty. We therefore do not present this installation as having a precise capacity without confirmation of the model number.
This is an important practice at AirGreen: we prefer verifiable technical information to an estimate based on the apparent size of the unit.
Why installation details matter as much as the heat pump's technical performance
Heating capacity that remains significant at -15 °C
One of the most relevant data points in the MIDEA35 technical sheet concerns low-temperature heating.
At -15 °C, the values published by Midea are:
- 13,500 BTU/h for the 9,000 BTU configuration;
- 13,500 BTU/h for the 12,000 BTU configuration;
- 22,600 BTU/h for the 18,000 BTU configuration.
The COPs indicated at this temperature are respectively 3.60, 3.60, and 4.40 under the published test conditions.
For us, this type of data is essential when a homeowner is looking for a heat pump for heating in Hudson.
It is not enough to know that a machine can start at -30 °C. You also need to understand how it performs when the building actually requires a great deal of heating.
Inverter technology helps maintain a more stable temperature
Midea uses variable-speed technology that allows the compressor to modulate its operation according to demand.
Rather than operating continuously in a full-capacity-shutdown-full-capacity cycle, the system can gradually adjust its output.
The documentation indicates that this technology reduces temperature fluctuations and provides more stable comfort compared with traditional on-off operation.
This also explains why heat pump sizing remains important.
Automatically choosing the model with the highest BTU rating is not necessarily the best strategy. A properly sized machine can use its modulation range more efficiently and provide more consistent comfort.
Refrigerant lines vary according to capacity
This Hudson installation shows a significant vertical run between the outdoor unit's location and the upper parts of the building.
Line compatibility therefore becomes essential.
For the MIDEA35, the 9,000 and 12,000 BTU versions use 1/4 in and 3/8 in.
The 18,000 BTU version instead uses 3/8 in and 5/8 in.
The specified maximum lengths are 82 ft for the two smaller capacities and 164 ft for the 18,000 BTU version. The published maximum height difference ranges from 49.2 ft to 82 ft depending on the model.
These specifications are particularly important when replacing an older heat pump.
A pre-installed line must never be considered compatible solely because it can be physically connected to the new machine.
A new generation using R-454B
The MIDEA35 uses R-454B refrigerant, classified as A2L.
Midea's documentation also lists an A2L refrigerant leak detection sensor among the features of this equipment family.
For a professional installation, this means that work practices must match the refrigerant being used.
The connections, leak tests, evacuation procedures, tools, and commissioning methods must all be adapted.
This is particularly relevant for homeowners replacing an older R-410A system. A new generation of heat pumps must not be treated as a simple cosmetic replacement for the old machine.
The electrical system must be suited to the selected capacity
All three MIDEA35 configurations operate at 208/230 V, single-phase, 60 Hz.
For the 9,000 and 12,000 BTU versions, the manufacturer specifies a minimum allowable ampacity of 16 A and a maximum protection of 20 A.
For the 18,000 BTU model, the minimum allowable ampacity is 24.9 A, with a maximum protection of 25 A.
When replacing a unit, we therefore check the existing circuit before confirming the compatibility of the new equipment.
An older heat pump with a different capacity may have been powered by a circuit that no longer meets the requirements of the new unit.
An installation under a staircase requires special consideration for maintenance
Hudson's project presents another very practical challenge: future access.
The metal staircase is immediately adjacent to the left side of the heat pump. The balcony is on the other side.
We are therefore dealing with a space that must remain functional enough to allow technical service work.
In the long term, a technician may need to:
- clean the outdoor heat exchanger;
- inspect the connections;
- measure electrical parameters;
- check the fan;
- access the service valves;
- investigate a fault;
- work on an internal component.
An HVAC installation should not merely be possible to assemble. It must remain possible to service.
This is a nuance that often makes all the difference between a quick installation and a thoughtful one.
The outdoor unit’s weight justifies sturdy mounting
The MIDEA35 9,000 and 12,000 BTU versions are listed at approximately 99.65 lb, while the 18,000 BTU outdoor unit weighs approximately 130.29 lb.
With a wall mount like the one at the Hudson job site, the support and its anchoring are therefore not secondary accessories.
The structure must support the machine’s static weight, as well as the forces and vibrations produced during operation.
We must also consider the support on which the mounting is installed. A foundation wall, a brick wall, and lightweight siding cannot be treated the same way.
Noise levels also depend on installation quality
Depending on capacity, Midea publishes indoor sound levels as low as 19 dB(A) for the 9,000 and 12,000 BTU models and up to 16 dB(A) for the 18,000 BTU model under certain operating conditions.
But a heat pump that is quiet on paper can become unpleasant if vibrations are transmitted to the building structure.
Stable mounting, properly positioned lines, and careful mechanical installation therefore directly contribute to acoustic comfort.
This is particularly important when an outdoor unit is mounted near a window or occupied room.
Useful everyday comfort features
The MIDEA35 also offers several features designed to improve everyday use: ECO mode, night mode, Wi-Fi control, timer, horizontal and vertical swing, silent mode, 8°C heating, and “Follow Me” function.
The documentation also indicates up to 100 fan speed settings and the ability to use the SmartHome app for remote control in applicable configurations.
These features make it possible to fine-tune comfort more precisely than with older generations of wall-mounted air conditioners with a few fixed speeds.
A design that also makes cleaning easier
For maintenance of the indoor unit, Midea indicates that the fan wheel can be removed to facilitate thorough cleaning and access to the inside of the unit.
This is an interesting detail over several years of use.
One wall-mounted heat pump gradually accumulates dust on the filters, evaporator, blower wheel, and certain internal surfaces.
Proper maintenance helps maintain good airflow and prevent a high-performing unit from gradually becoming less efficient after installation.
Subsidies: always verify the precise AHRI number
For a homeowner checking eligibility for a financial assistance program, the exact installed combination must be used.
The three MIDEA35 units described in the brochure bear the AHRI reference numbers 215471386, 215471387 and 215471388, with Cold Climate V6.1 certification indicated in the documentation.
Eligibility for LogisVert or another program must nevertheless be confirmed according to the criteria applicable when the application is submitted.
The trade name “MIDEA35” should not be used alone to determine a subsidy amount.
A warranty that must be documented at the time of installation
The Midea brochure mentions a residential limited warranty program of up to 12 years for the compressor, 12 years for parts, and 10 years for labor, according to the applicable terms.
We always recommend keeping the serial numbers, exact model numbers, invoice, and associated system registration documents.
A warranty lasting several years is truly useful when installation information can still be easily retrieved long after the work is completed.
What this Hudson installation shows about our approach at AirGreen
This installation is interesting because the main challenge was not visible on a technical specification sheet.
We had a narrow outdoor space narrow, framed by a metal staircase and a balcony, with a brick façade, an existing foundation, and a vertical route to be arranged for the lines.
Our task was therefore to use this space intelligently without compromising the heat pump’s technical requirements.
The visible result in the photo shows:
- an outdoor unit a Midea unit securely mounted on wall brackets;
- an unobstructed front fan;
- clearance beneath the unit;
- a vertical pipe cover matching the façade;
- a compact installation that fits between the existing structures;
- access maintained for servicing.
This is the approach we also apply to our heat pump and air conditioning in Montreal, Laval, Longueuil, on the North Shore and the South Shore.
The MIDEA MIDEA35 offers technical features particularly well suited to Quebec: heating operation down to -30 °Cinverter technology, refrigerant R-454Bhigh efficiency, precise ventilation control, and cold-climate certification.
But this Hudson project above all highlights an essential rule: A heat pump’s performance depends as much on how it is installed as on the figures listed in its brochure..
The job tools
Two quick checks with real numbers: what heat costs, and what your current heaters add up to in BTU/h.
Baseboards and electric furnaces turn 1 kWh of electricity into 1 kWh of heat. A heat pump delivers more: that is its COP. At Hydro-Québec’s rate D (11.142¢/kWh above 40 kWh a day, since 1 April 2026):
Hydro-Québec: a heat pump can be up to three times more efficient than baseboards for heating in the colder months.
Estimate per kWh of heat, at the chosen temperature, using the certified COP from the product page. Taxes, access charge and backup heat not included.
Conversion: 1 W = 3.412 BTU/h. An indication, not a load calculation: baseboards and furnaces are often stronger than the real need, and they can stay as backup. AirGreen confirms the capacity on site.
How the job unfolds
The main steps of this kind of job at AirGreen. Every house has its quirks: the estimate brings them out.
We look at the room, the outside wall, the line route and where the outdoor unit will go. That is where the capacity gets chosen.
Model, capacity and price, in writing. We also check whether the model qualifies for assistance programs.
Floors and furniture protected, wall plate position marked level, wall opening located.
A single opening, with the slope the drain needs to flow outside.
Set on a stand raised above the snow, with the clearances the manufacturer requires.
Connected, insulated and protected. The opening is then sealed against water, cold air and insects.
A dedicated circuit and an accessible disconnect near the outdoor unit.
Leak test, vacuum, then start-up and a check of heating and cooling.
Remote, modes, filters: we show you the essentials before we leave.
- The on-site estimateWe look at the room, the outside wall, the line route and where the outdoor unit will go. That is where the capacity gets chosen.
- The quoteModel, capacity and price, in writing. We also check whether the model qualifies for assistance programs.
- Getting readyFloors and furniture protected, wall plate position marked level, wall opening located.
- The wall openingA single opening, with the slope the drain needs to flow outside.
- The outdoor unitSet on a stand raised above the snow, with the clearances the manufacturer requires.
- Lines, cable and drainConnected, insulated and protected. The opening is then sealed against water, cold air and insects.
- The electrical workA dedicated circuit and an accessible disconnect near the outdoor unit.
- Tests and start-upLeak test, vacuum, then start-up and a check of heating and cooling.
- The walkthroughRemote, modes, filters: we show you the essentials before we leave.
What we check on a job like this one
Each number is a point we check on site. Switch between summer and winter to watch air and heat move.
In summer, the outdoor unit rejects the house's heat outside.
Generic illustration of this type of installation, not a survey of this job site. Tap a number.
Mounted level on a wall plate, high enough for the air to reach the whole room, with enough space around it to slide the filters out easily.
The refrigerant lines, the communication cable and the drain go through the wall in a single opening, sealed against water, cold air and insects.
Two insulated copper pipes connect the two units. Outside, a line cover can protect them from sun, knocks and weather.
A shut-off switch near the outdoor unit isolates it safely for service. It must stay accessible at all times.
The compressor and the fan. In heating mode it captures heat from the outdoor air, even in winter, and moves it inside.
On the ground or on the wall, it keeps the unit above accumulated snow. The unit stays clear and defrost water can drain away.
The fan needs to blow freely. Storage, a fence or a wall too close, and efficiency drops while noise goes up.
Is your home ready?
Check what applies at your place. A "no" is not a refusal: it is what we sort out during the estimate.
Good habits, once the unit is in place
Six simple habits that keep the unit going. Your list stays on this device.
What to do, season by season
Three habits per season for this unit. They take a few minutes and prevent many calls.
- Clean the indoor unit's filters.
- Clear leaves and debris left on the outdoor unit by winter.
- Test cooling before the first hot days.
- Clean the filters more often when the unit runs a lot.
- Keep plants away from the outdoor unit.
- Check that no water drips from the indoor unit.
- Rake the leaves around the outdoor unit.
- Test heating before the first cold days.
- Book periodic maintenance before winter.
- Keep snow away from the stand and the front of the unit.
- Let the unit defrost: it is normal.
- Never hit the ice on the fins; call us if the unit stays iced up.
The right pages, at the right time
Four statements: true or false?
It all comes down to details you have just seen.
1. In heating mode, the outdoor unit can produce water.
During defrost cycles. That water must drain away without forming ice.
2. You pick the capacity with a simple square-footage rule.
Windows, insulation, orientation and how the room is used all count. Capacity is chosen on site.
3. A multi-zone connects several indoor heads to a single condenser.
One head per room, all on the same condenser. Each room keeps its own temperature.
4. The disconnect can sit behind the patio furniture.
It must stay accessible: it is what shuts the unit off for service.
0 / 4 right answers
What people ask us about this kind of work
Does a wall-mounted heat pump heat in winter?
Wall-mounted or multi-zone: how do I choose?
Where does the outdoor unit go?
Are there grants?
Do I need a permit?
How cold can it heat?
How much can I save?
How is the LogisVert assistance calculated?
Is it noisy?
The outdoor unit is covered in ice: is that normal?
Does AirGreen hold the required licences?
Is the estimate free?
No question matches. Write to us: we answer.
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Text and photo: a real AirGreen Climatisation & Chauffage job. The diagrams are generic illustrations of the type of installation, not a survey of this job site. Sources of the added figures: airgreen.ca product pages (NEEP / AHRI performance), Hydro-Québec (Heat pumps page, LogisVert, read on 13 October 2026), Régie de l’énergie (rate D as of 1 April 2026).