Four ducts, four functions: the stage where half of installations go wrong
In the photo from this Pointe-Claire job, two details immediately stand out to a technician but go unnoticed by everyone else: the word INTAKE written with a marker on a galvanized duct, and a hand-drawn arrow showing the direction of airflow. This is not decoration. It is evidence of a method.
An air exchanger has four connections, and all four look alike. Fresh air from outside, fresh air distributed throughout the house, stale air extracted from the house, and stale air exhausted outdoors. Switching two of them triggers no alarm, makes no noise, and shuts nothing off. The unit runs, the client hears the fan, and everything seems normal—except that the house receives exhausted air or expels outdoors the air it has just tempered.
We label the four ducts with a marker on site at the time of connection. The next technician who opens this room in eight years will know what they are looking at.
The setting: a West Island split-level with no clear mechanical space
The house is a typical split-level in the area, built in the 1970s and expanded once, with a partially buried basement on the Lake Saint-Louis side. The available mechanical room was a storage room adjoining the laundry room: finished ceiling, no accessible joists, a storage wall on one side, and a door on the other.
The homeowner called us with a simple problem: the basement smelled musty year-round, and in winter, the downstairs bedroom window leaked enough to stain the frame.
Why this unit sits on the floor instead of being suspended from the ceiling
Chain suspension is the default method in an unfinished basement where the joists are accessible. Here, it was impossible: finished ceiling, insufficient headroom, and a 59 lb unit to anchor into drywall.
We mounted the HERO 200H on a metal base set on the floor, with the connections facing upward. This configuration offers three concrete advantages in this type of space:
- Service access at working height. Removing the core and filters is done standing up, without a step stool or contortion. A unit that is difficult to access is a unit that does not get maintained.
- Structural noise isolation. A housing anchored to a frame transmits its vibrations into the wood; a floor-mounted base on a concrete floor transmits nothing to the upper floor.
- Gravity condensate drainage to the floor drain, with no condensate pump and therefore no additional moving part that could fail.
The trade-off: the unit takes up floor space. We therefore verify, before proposing this approach, that sufficient clearance remains in front of the access door to remove the entire core.
Choosing the Fantech HERO 200H
After the addition, the house has nine main rooms, with three bathrooms. The airflow calculation placed the continuous requirement well above what a 100 cu. ft./min. unit can support without running continuously at full speed.
- Airflow range: 76 to 203 cu. ft./min. at 0.4 in. water column
- Connections: 6 in., round, on top
- Dimensions: 24 7/8 in. (H) x 27 7/8 in. (W) x 15 3/8 in. (D)
- Weight: 59 lb
- Power supply: 120 V, 2.0 A max.
- Power consumption: 98 W at low speed, 210 W at high speed
- Adjusted sensible recovery efficiency: 88 %
- Sensible recovery: 80% at 0 °C, 67% at -25 °C
- Defrost: by recirculation, with a mechanical backdraft damper
- Filtration: MERV 8 or optional MERV 13
The most important figure in this list is the 67% at -25 °C. Most technical specifications highlight efficiency at 0 °C, a condition that corresponds to a November month in Pointe-Claire. It is in January, at -25 °C, that heat recovery has the greatest value—and that is precisely the column that comparison charts omit.
Recirculation defrost, and why we favor it
Below approximately -5 °C, moisture in the stale air begins to freeze in the core. Fantech has two mechanisms.
Supply fan shutdown is simple and robust: the fresh-air intake stops while the core defrosts. During a week of sustained cold, the minutes add up.
Recirculation defrost closes the outdoor intake with a mechanical damper and circulates indoor air through the core. Air circulation never stops, and stagnant air that contributes to winter condensation does not settle in closed rooms. In a home where window condensation was the initial symptom, this was the decisive criterion.
Rigid or flexible: where we use each, and why
The two types of duct visible on this job are not an aesthetic choice.
Galvanized rigid duct on the interior runs
Rigid duct has a smooth wall: at the same diameter, its pressure loss is significantly lower than that of flexible duct, whose spirals create continuous turbulence. It can be cleaned, it does not sag, and it does not get punctured when it comes into contact with a storage box. On the main runs, this is what makes it possible to reach the calculated airflow without running the unit at high speed constantly.
Insulated flexible duct on the exterior runs
The two black ducts in the photo connect the unit to the exterior hoods. They are insulated with a continuous vapor barrier, and this insulation is non-negotiable. An uninsulated fresh-air duct passing through a heated space becomes covered in condensation along its entire length; the water accumulates, stains the ceiling, and then rots the drywall. This is the most common repair we perform on installations taken over in the West Island.
The flexible duct is justified here because it absorbs misalignment and dampens some of the fan noise before the air reaches the exterior wall.
Electrical connection and control wiring
The unit plugs into a 120 V outlet—visible behind it on the wall. A dedicated outlet remains best practice: sharing the circuit with a freezer, washing machine, or sump pump causes sporadic trips that are difficult to diagnose six months later.
The low-voltage cable connected to the terminal block on top of the cabinet links the unit to its wall control and, depending on the configuration, to bathroom timers. This wiring determines what the client will actually be able to do with the system: switch to high speed during a shower, change to recirculation mode, or let a control with volatile organic compound detection, such as the ECO-Touch IAQ, adjust the airflow automatically.
Commissioning: measure, do not estimate
The label affixed to the unit establishes the relationship between the airflow in cfm and the measured pressure at the designated test ports. We measure at Normal speed using a differential manometer, then adjust the dampers until the supply and exhaust are balanced within a 10% tolerance.
What an unbalanced unit causes is tangible. With excessive exhaust, the house becomes depressurized and draws air in through the foundation, crawl space, and floor drain—in a partially below-grade basement near the lake, that is exactly the air we do not want to bring inside. With excessive supply, humid indoor air is pushed into the wall cavities, where it condenses against the exterior cladding.
The readings are recorded and provided to the client. Without a record, no one can know three years later whether the unit has drifted.
Regarding subsidies
The current Quebec programs—LogisVert, Rénoclimat, and Chauffez vert—target heat pumps, insulation, air sealing, and the replacement of oil-fired systems. To our knowledge, none directly subsidizes the addition of an HRV during a renovation. Balanced mechanical ventilation, however, is a requirement for Novoclimat certification in new construction. We prefer to state this clearly rather than let a client hope for a reimbursement that will not come. Programs change, so we verify eligibility when preparing the quote instead of relying on a dated web page.
Errors specific to this type of installation
- Reversing two of the four ducts. Nothing indicates the mistake, and the system operates backward for years. Labeling them with a marker during the connection takes thirty seconds.
- Making everything flexible ductwork to save time. The airflow measured during commissioning ends up 20 to 30% below the target, and the unit must run at high speed continuously to compensate.
- Installing the unit on the floor without access clearance. The core must be able to be removed completely.
- Failing to insulate the exterior sections.
- Placing the exterior hoods too close together. A separation of at least 6 feet prevents expelled air from being immediately drawn back in.
- Never cleaning it. Filters checked every three months, the core washed once a year, and exterior hoods cleared of snow and lint. In Pointe-Claire, spring pollen from wooded areas and shorelines clogs filters faster than the Montreal average.
Our ventilation practice in the West Island and Greater Montreal
At AirGreen, we design and install residential ventilation systems in Pointe-Claire, Beaconsfield, Kirkland, Dollard-des-Ormeaux, and Dorval, as well as in Montreal, Laval, Longueuil, on the North Shore, and on the South Shore. Homes in the West Island present particular constraints: split-levels with challenging duct routes, partially buried basements, proximity to the lake, and high soil moisture.
Our method remains the same from one job to the next. We calculate the airflow before selecting the unit. We verify that the chosen model physically fits in the available space, including service clearances. We prioritize rigid ductwork where airflow matters most. We identify the connections. We balance the system with a manometer and provide the readings.
For an assessment of a HVAC installation or the addition of an air exchanger in Pointe-Claire, the West Island, or elsewhere in Greater Montreal, our team comes to your home, takes measurements, and recommends a system sized for the actual house.