A compact installation designed for the comfort of a room with extensive glazing
In Mercier, on Montreal's South Shore, we installed a FORESTAIR PTAC in a bedroom where the architectural layout required a particularly precise approach. The room is bordered by a large glazed surface overlooking the outdoors, an element that provides plenty of natural light but also strongly influences the indoor temperature.
A large window can become a significant source of heat on sunny days and create a cold-wall sensation during the winter. In a bedroom, these temperature variations are quickly noticeable, especially when the bed, furniture, or circulation space is close to the glazing. The objective of this intervention was therefore clear: to provide a self-contained unit capable of maintaining a comfortable temperature without unnecessarily occupying wall space or requiring the installation of a duct network.
The PTAC, sometimes called a packaged terminal air conditioner, combines the main components required to heat and cool the room in a single cabinet. It passes directly through the exterior wall using a suitable sleeve. This design is particularly well suited to bedrooms, apartments, hotels, residences, rental buildings, and certain commercial spaces.
In this HVAC project in Mercier, the FORESTAIR unit was positioned under the window, in a location that would effectively address the heat gains and losses associated with the glazing. The result is a compact, accessible installation suited to the room’s daily use.
Why install the PTAC directly under the window?
The location of a heating and air-conditioning unit should never be chosen solely based on available space. The natural movement of air, heat sources, exterior-facing walls, and furniture layout must also be considered.
Under a large window, the FORESTAIR PTAC can act directly on the area where temperature variations are generally greatest. In cooling mode, it helps limit the buildup of heat caused by sunlight. In heating mode, depending on the configuration and the model’s capabilities, it helps reduce the sensation of cold near the glazing.
Positioning it under the window provides several advantages:
- better air distribution in the room;
- a quick intervention to reduce heat loss through the glazing;
- efficient use of the lower part of the wall;
- convenient accessibility for use and maintenance;
- the absence of a wall-mounted unit installed near the ceiling;
- a self-contained solution for a room or specific area.
In this installation, the available space was relatively tight. The PTAC had to fit between the side wall, the window, and the passage leading to the glass door. We therefore paid particular attention to the unit’s alignment, access to the control panel, and the clearance required in front of the air circulation grilles.
An installation that must respect the building envelope
A PTAC passes through the exterior wall. The quality of the opening and its airtightness are therefore just as important as the choice of the unit itself.
An improperly prepared opening can cause several problems:
- air infiltration;
- water penetration;
- condensation formation;
- discomfort near the unit;
- vibrations transmitted to the structure;
- premature deterioration of the materials surrounding the sleeve;
- excessive noise during operation.
During our PTAC installations in Mercier, Montreal, Laval, Longueuil, on the North Shore and the South Shore, we check the structure, the sleeve’s level, the support surfaces, and the sealing points. The cabinet must be installed securely while maintaining the slope and clearances required for proper operation.
In the project presented, the PTAC is properly inserted into an opening located beneath the glazing. The front panel remains accessible from the room, while the rear section connects to the outside through the wall sleeve.
Leveling: a subtle detail that changes everything
A PTAC must not be placed approximately in its opening. Its positioning affects, among other things, condensate drainage and noise levels.
An improperly levelled unit can produce trickling noises, retain water, or transmit more vibrations to the structure. We must therefore check the sleeve’s support and the stability of the unit once inserted.
For a project like the one in Mercier, our inspections include, among other things:
- the strength of the opening;
- the alignment of the sleeve;
- the stability of the cabinet;
- the clearances around the air intakes and outlets;
- proper condensate drainage;
- the condition of the seals between the installation and the building;
- the operation of the control panel;
- the unit’s response in the various available modes.
These steps help reduce the risk of service callbacks and ensure more comfortable use over the long term.
An easy-to-access integrated control
The control panel of the FORESTAIR PTAC is located on the upper part of the unit. This configuration makes it easier to adjust the temperature and operating mode without having to access a remote thermostat.
In the project photograph, the digital display is clearly visible. The controls allow the occupant to view and adjust the settings directly on the cabinet.
For a bedroom, this accessibility is particularly useful. The user can quickly adjust the temperature before going to sleep, upon waking, or when outdoor conditions suddenly change.
Depending on the exact PTAC model, available functions may include air conditioning, ventilation, different fan speeds, and a heating function. We always verify the actual features of the installed appliance rather than assuming that all PTACs offer the same performance.
The power supply must precisely match the appliance
A PTAC must be powered by an electrical circuit suitable for the data listed on its rating plate. The voltage, minimum circuit ampacity, and maximum overcurrent protection must not be determined solely from the appearance of the plug.
In this room, the power cord reaches an outlet on the adjacent wall. Before starting the appliance, it is essential to verify that the outlet, circuit, and electrical protection meet the manufacturer's requirements.
Among the mistakes to avoid are:
- permanent use of an extension cord;
- plugging into a damaged outlet;
- sharing the circuit with several energy-intensive appliances;
- using an unapproved adapter;
- replacing electrical protection with a higher-capacity circuit breaker;
- installing an appliance whose voltage does not match the existing circuit.
The technical data sheet and rating plate remain the primary references. A model designed to operate at a given voltage must never be substituted for another without verifying the electrical installation.
What this PTAC installation in Mercier teaches us
The grilles must remain completely unobstructed
The photograph highlights an important point for all owners and occupants using a PTAC: textiles, curtains, and objects must not obstruct the air grilles.
The curtain is very close to the top of the appliance, and fabric has been placed on the windowsill above the PTAC. Even when they appear to be a few centimeters away, these items can move with the airflow and partially cover an intake or outlet.
An obstruction can cause:
- poor air distribution;
- longer operating cycles;
- increased electricity consumption;
- less uniform temperature;
- noisier operation;
- a buildup of dust on the heat exchanger;
- overheating or protection of the appliance in certain cases.
We recommend keeping the top and front of the PTAC completely clear. Curtains should be tied back or adjusted so they cannot be drawn toward the grille.
You should also avoid using the top of the cabinet as a shelf for clothing, towels, bags, or other items. This habit is common in rooms where space is limited, but it directly compromises airflow.
Filter maintenance affects comfort and noise
Like any heating and cooling equipment, a PTAC must be maintained. The indoor filter traps some of the dust and particles present in the room. When it becomes clogged, airflow decreases.
The unit may then run longer to reach the requested temperature. The fan may become more audible, while the actual heating or cooling capacity decreases.
Routine maintenance generally includes:
- inspection and cleaning of the filter;
- dusting the grilles;
- checking that there are no objects around the unit;
- inspection of the cabinet and sleeve;
- monitoring for any unusual noise or leaks;
- professional cleaning of the components when necessary.
The cleaning frequency depends on how the room is used, the presence of pets, the level of dust, and whether the unit operates continuously or seasonally.
In a rental property or a multi-unit building, it is best to establish a clear maintenance procedure. The filter must be accessible, and occupants should understand that a clogged unit cannot maintain its normal performance.
A PTAC Is Not a Portable Air Conditioner
A PTAC is sometimes confused with a portable air conditioner temporarily placed in a room. However, the two pieces of equipment are very different.
A portable air conditioner generally exhausts hot air through a flexible duct installed in a window. It takes up floor space and often must be moved or stored at the end of the season.
The FORESTAIR PTAC, on the other hand, remains installed in the wall. It uses a permanent opening and an outdoor grille. It does not require a flexible duct running through a window and generally leaves more available space in the room.
This solution is particularly appealing when:
- installing a central system is not possible;
- each bedroom must have its own control;
- the building already has openings for PTACs;
- the condominium association imposes restrictions on outdoor units;
- the occupant wants to avoid a wall-mounted unit near the ceiling;
- the room requires a self-contained and accessible solution.
A selection based on the room, not just on BTUs
The capacity of a PTAC must match the room’s actual heating load. Automatically choosing the most powerful unit is not a good strategy.
An oversized unit can quickly reach the set temperature without running long enough to provide satisfactory humidity control. It may also cause more noticeable temperature fluctuations and frequent start-up cycles.
An undersized unit may instead run almost continuously without maintaining comfort during the hottest or coldest periods.
To determine the appropriate capacity, we consider in particular:
- room area;
- ceiling height;
- the number and orientation of windows;
- insulation quality;
- sun exposure;
- the number of occupants;
- heat-generating appliances;
- the floor where the room is located;
- the desired temperature;
- the model's actual capacities under operating conditions.
The large amount of visible glazing in this Mercier installation is an important factor. Two bedrooms of the same size may require different solutions when one has a small window and the other is almost entirely glazed.
Financial assistance must never be assumed
Financial incentives available for HVAC work in Quebec depend on the program, the type of building, the technology installed, and the equipment's exact model.
A PTAC should not automatically be presented as eligible for the same assistance as a cold-climate certified wall-mounted heat pump or a central system meeting specific criteria.
For this project, we make no claims about eligibility without the complete model references and the conditions applicable at the time of application. Before basing a purchasing decision on financial assistance, obtain written confirmation and verify that the unit appears on the lists of accepted equipment, when such lists are required.
Common mistakes to avoid after installation
Even a professional installation can lose some of its efficiency if the unit is used improperly. We recommend that occupants avoid several common mistakes:
Covering the top of the PTAC
Clothing, towels, and curtains restrict airflow. The cabinet must remain unobstructed.
Constantly changing the temperature
Significant and repeated changes to the set temperature can increase operating time without improving comfort. A stable temperature is generally preferable.
Neglecting the filter
A clogged filter reduces airflow and can increase operating noise.
Placing furniture in front of the unit
A bed, chair, suitcase, or piece of furniture placed too close to the PTAC can prevent air from circulating properly throughout the room.
Ignoring a new noise
An unusual sound, vibration, or leak warrants an inspection. Waiting can turn a minor adjustment into a more significant repair.
Using an extension cord
The PTAC must be connected according to the electrical requirements specified for the equipment. An extension cord is not an appropriate permanent solution.
A practical solution for property owners and building managers
PTACs are often selected for buildings where each room or dwelling must be controlled independently. This autonomy allows an occupant to select their temperature without directly affecting the other spaces.
For a property manager, this configuration also simplifies certain tasks. Work on one unit can generally be performed without interrupting the operation of all the other units in the building.
However, consistency must be ensured in the selection, maintenance, and replacement of equipment. When an old PTAC must be replaced, we specifically check:
- the dimensions of the existing sleeve;
- the condition of the exterior grille;
- electrical voltage;
- the capacity of the old unit;
- interior clearances;
- condensation management;
- compatibility between the new cabinet and the opening;
- the room's actual needs.
A unit that appears similar may have different dimensions, power requirements, or specifications. Prior validation avoids unexpected modifications on the day of the work.
Our approach to PTAC installations on the South Shore
At AirGreen, we approach a PTAC installation as a complete project involving comfort, the building, electricity, drainage, and everyday use.
In this bedroom in Mercier, the challenge was not simply to place a unit in an opening. It had to be integrated into a narrow space near a large window and a passageway, while preserving access to the controls and airflow.
We therefore focused our attention on:
- the stability of the PTAC;
- the quality of its integration beneath the window;
- accessibility of the control panel;
- clearances around the grilles;
- electrical compatibility;
- start-up and testing;
- the operating recommendations provided to the occupant.
This method applies to our HVAC projects in Mercier, Châteauguay, Candiac, Longueuil, Boucherville, Laval, and Montreal, as well as in other areas of the South Shore and North Shore.
The visible installation demonstrates that a FORESTAIR PTAC can be an appropriate solution for a room with extensive glazing when the location, wall opening, and electrical conditions are properly assessed.
Final comfort then depends on a few simple practices: keep the grilles clear, clean the filter, avoid extension cords, maintain a reasonable setpoint, and have any unusual behavior inspected promptly.