Installation of a vänEE AI Series V160H75RT air exchanger in Ormstown, in the Châteauguay Valley

Replacing a 25-year-old air exchanger in Ormstown: the connection matters as much as the unit

A home in Ormstown, on a quiet country road a few minutes from the Châteauguay River, with a finished basement, an existing forced-air heating system, a central vacuum, and a duct network installed properly when the house was built. Nothing unusual. What prompted the call: the original air exchanger, installed in the mid-1990s, was no longer delivering any airflow. The owner held a hand in front of the bathroom grille and felt no suction.

We replaced this unit with a vänEE Série AI V160H75RT, an HRV with top-mounted ports. But the real work that day was not suspending the cabinet. It was redoing the connection to the existing duct network, because that is where the actual performance of a heat exchanger in a forced-air-heated home is determined.

The condition of the system: a working but useless unit

The original unit was running. Both motors worked, the indicator light was on, and the owner therefore believed it was in good condition. Our inspection revealed something else:

• The core was clogged across two-thirds of its surface by 25 years of compacted dust. Heat recovery had become marginal, while the pressure drop was enormous.
• The original interior filters, made of foam, had never been replaced and were disintegrating at the touch.
• The outdoor fresh-air intake was partially blocked by a nest.
• More importantly, the unit had been connected using what is known as a simplified setup: both the stale-air exhaust and the fresh-air intake were tapped into the furnace return duct, less than 18 inches apart.

This last point is what made the unit useless even when it was new. Two connections placed too close together on the same return duct create a short circuit: the heat exchanger draws in the air it has just blown out, passes it through its core, exhausts it outside, and starts over. The house barely benefits. On paper, it is ventilated. In practice, the air in the bedrooms and bathrooms does not move.

The forced-air network: three ways to connect an HRV, and the only one we recommend

In Quebec, a heat recovery ventilator can be paired with a forced-air system in three ways. They are not equally effective.

The fully dedicated setup

The exchanger has its own network: exhaust grilles in the bathrooms and laundry room, supply grilles in the bedrooms and living areas, with no connection to the heating ducts. This is the highest-performing and most independent configuration. It also requires the most openings and ductwork, so it is rarely practical in an already finished home.

The simplified setup

Both connections are made to the return duct of the forced-air system. It is quick, economical, and the configuration we most often see executed incorrectly. It requires two conditions without exception: sufficient separation between the two takeoffs, generally at least one metre, and mandatory operation of the furnace fan whenever the exchanger is running. Without the central system's fan, the fresh air remains trapped in the return duct and goes nowhere.

The partially dedicated setup, our choice in Ormstown

This is the compromise we recommend in the vast majority of existing homes in Montérégie, Rive-Sud, and Rive-Nord:

• The exhaust is completely dedicated. We draw stale air directly from where it deteriorates: the two bathrooms and the laundry room, using adjustable wall grilles.
• The fresh air supply is injected into the forced-air system's return duct, allowing it to be distributed throughout the house without opening a single additional ceiling.

Short-circuiting becomes impossible because the two circuits no longer share the same duct. The bathrooms are genuinely ventilated. Comfort also improves because the January outdoor air, already warmed by the core to approximately 15 °C, is tempered further as it passes through the central system before reaching the grilles.

We also added fan interlocking between the heating unit and the air exchanger, so both start at the same time. It is a simple control connection that is often overlooked, and without it, half the benefit of the installation is lost.

Why the vänEE AI Series V160H75RT in this home

The choice was not made out of habit. Three site constraints guided the selection.

The layout of the space. The ducts came in from above, between the joists. A unit with side outlets would have required two additional tight bends in a space already occupied by the central vacuum and plumbing. The V160H75RT is the version with top outlets, with four 6 in. collars oriented upward: the ducts run straight into the joists, without unnecessary bends.

Airflow. The unit covers 35 to 159 CFM, with continuous modulation across the entire range. For this four-bedroom house with a finished basement, our total ventilation capacity calculation placed the need at around 60 CFM in continuous operation, with higher-speed peaks during showers. The unit’s useful range places this setting in the quiet zone.

Cold-weather performance. Sensible recovery efficiency (SRE) reaches 77% at 0°C and remains at 65% at -25°C. In the Châteauguay Valley, where January nights regularly fall below -25°C with wind moving up the river corridor, it is the second figure that determines the electricity bill and comfort.

The rest of the technical data:

• PMSM ECM motors on both fans, for contained energy consumption during continuous operation.
• Recirculation defrost, which protects the core without ever depressurizing the house.
• Built-in LCD screen on the unit, allowing you to select the target airflow directly in CFM and read the measurement in real time, with self-diagnostics.
• Standard MERV 8 interior filters, with the option to upgrade to MERV 13—an option we selected here for an agricultural reason explained below.
• Casing measuring 21 1/2 in. high, 21 in. wide, and 16 3/8 in. deep, weighing 35 lb, suspended by universal brackets and chains.
• HVI-certified and ENERGY STAR-qualified unit.
• Wall-mounted touchscreen controls and a dehumidistat are available separately.

The Ormstown factor: air in an agricultural municipality

Ormstown is sustained by agriculture: dairy farms, cash crops, and equestrian operations. Twice a year, in spring and late summer, the neighboring fields are sprayed. During these periods, the outdoor air carries odors and particles that no one wants entering through the fresh-air intake for three days.

That is exactly why we chose the MERV 13 interior filters instead of the standard MERV 8. MERV 13 captures a significant share of the fine particles, grass pollen, and harvest dust circulating along the road in August. We also showed the homeowner how to temporarily lower the airflow to its minimum from the LCD screen during spraying days, then return to the normal setting afterward.

The second local consideration is that the house has a central vacuum whose motor unit exhausts outdoors. Whenever it operates, it removes air and puts the house under slight negative pressure. In a well-sealed home with a combustion appliance, this negative pressure adds to that created by range hoods and dryers. A balanced HRV, which supplies as much air as it exhausts, does not correct everything, but it prevents the situation from getting worse, unlike an exhaust-only system.

The work, completed in one day

1. Removal of the old unit. Electrical disconnection, duct removal, lowering the cabinet, and recycling the metal.
2. Correction of the existing ductwork. The old 5-inch connections were replaced with 6-inch ducts along all four runs. Reusing 5-inch ductwork on a unit designed for 6 inches amounts to deliberately strangling the appliance you just paid for.
3. Suspension. Universal supports and four chains anchored to the joists, with the unit level in both axes. Leveling is not cosmetic: a tilted cabinet retains water in its pan instead of directing it to the drain.
4. Reworking the supply connection on the return duct, at a suitable distance from all other connections, with screwed and sealed collars.
5. Dedicated exhaust network to both bathrooms and the laundry room, using insulated ductwork in sections passing through cold spaces.
6. Condensate drain connected with a trap and a continuous slope toward the floor drain.
7. Control wiring: connecting the ventilator to the heating appliance for fan control, and installing a wall control on the main floor.
8. Commissioning and balancing: measuring supply and exhaust airflow, adjusting them until they are equal, setting the continuous operating speed, and checking the defrost cycle.
9. Owner training: reading the display, maintaining the core, and following the indoor filter replacement schedule.

Leaving in the late afternoon, with the house properly ventilated.

HRV or ERV: our decision framework for Québec homes

The question comes up with every heat-recovery ventilator quote, whether in Montréal, Laval, Longueuil, or the Montérégie region. Here is how we decide.

HRV, our default recommendation

The heat recovery ventilator (HRV) transfers heat but not humidity. It therefore exhausts excess water vapour outdoors. In a typical Quebec home—showers, cooking, laundry drying, plants, and occupants—that is precisely what we want in winter. The vast majority of single-family homes we equip are better served by an HRV.

The ERV, in specific cases

The energy recovery ventilator (ERV) also transfers some humidity. It is useful in three situations:

• A home where the air becomes excessively dry in January despite moderate ventilation, often because it is lightly occupied or very large.
• A home with heavy air conditioning in summer, where an ERV limits the entry of outdoor humidity.
• Certain condos and apartments where occupancy is low relative to the volume.

An ERV is not a “superior” appliance; it behaves differently. Installing an ERV in an already humid home means retaining indoors what you were trying to exhaust.

The connection errors we correct most often

1. Two takeoffs positioned too close together on the return duct, creating the short-circuit described above.
2. No interlock with the heating appliance's fan, allowing fresh air to stagnate in the ductwork.
3. Exhaust air connected to the central system's return, sending bathroom air throughout the house.
4. 5-inch ducts retained on a 6-inch unit, resulting in reduced airflow.
5. Old wall control left in place, incompatible with the new unit's electronics.
6. Unit installed in an unheated garage or a cold crawl space, where condensate freezes in the drain pan.
7. No airflow measurement during commissioning, which amounts to delivering an appliance whose performance no one knows.

The applicable financial assistance

The Rénoclimat program provides a $500 grant for installing or replacing an HRV or ERV, provided that the model appears in section 3 of the certified products directory of the Home Ventilating Institute (HVI). The AI Series is listed there. Two practical points: an energy assessment is required before and after the work, and the home's EnerGuide rating must improve between the two visits. An air exchanger installed on its own rarely achieves this; combined with basement insulation, air sealing, or replacement of a heating system, it strengthens an eligible application. We help our clients plan this sequence before getting started.

Our air exchanger installations throughout Greater Montreal

The Ormstown case is repeated in different forms elsewhere. In Howick and Sainte-Martine, the work mainly involves replacing units from the 1990s in townhouses. In Saint-Rémi and Châteauguay, suburban homes often require rethinking the original simplified installation. On the North Shore, in Mascouche and Sainte-Thérèse, we often work in certified homes where the unit exists but has never been balanced. In Longueuil and Brossard, condominiums present the challenge of sharing duct runs between units. In Montreal, in Ahuntsic and Villeray, the issue is almost always available space and future access to the core. In Laval, renovated bungalows regularly fall into the category of homes that have become too airtight to ventilate on their own.

Entrust your air exchanger installation or replacement to AirGreen

We are an HVAC company based in Montreal, licensed under RBQ 5645-9605-01, with more than fifteen teams on the road and coverage extending from downtown to the municipalities of the Haut-Saint-Laurent: Ormstown, Howick, Très-Saint-Sacrement, Godmanchester, Saint-Chrysostome, Huntingdon, and the surrounding areas. We measure airflow before recommending a unit, systematically balance systems during commissioning, and provide the recorded values in writing.

For an air exchanger installation, replacing an aging HRV, reconnecting to a forced-air system, balancing, or complete HVAC maintenance in Montreal, Laval, Longueuil, the North Shore, the South Shore, or Montérégie, email us at sales@airgreen.ca or call (514) 316-2973. We assess your home on-site and provide you with a detailed quote.