Suspending an HRV in a 24-inch ceiling recess: the constraint that dictated the entire installation
The assignment we received in Dundee was not an ordinary HRV replacement. The home, a renovated single-story construction in rural Montérégie, had neither an unobstructed mechanical basement nor an accessible crawl space. The only viable location was in a ceiling recess built above a storage area, enclosed by a hatch and bordered by trim—a usable space approximately 24 inches deep, with a floor above it and a return-air grille less than a foot from the frame.
At AirGreen, we regularly see this type of setup, both in townhouses on the South Shore and in renovated plexes in Montreal. What makes all the difference is the method: an air exchanger installed in an enclosed space without service clearance becomes, within three years, a unit that no one maintains. The unit selection and installation geometry therefore had to solve this problem from day one.
Why the vänEE AI Series V150H75NT Was the Right Choice Here
The V150H75NT belongs to vänEE’s AI series, built on the Virtuo Air Technology platform. Three features made it the right choice for this project.
The top ports. The “T” suffix indicates a top-connection configuration. In a shallow recess, routing all four ducts out through the top completely frees the sides and front of the unit: the access door remains operable, and the ducts run directly to the attic without a 90-degree elbow pressed against a partition. A side-port model (V150H75NS) would have required at least six inches of clearance on each side, which we simply did not have.
Dimensions. The unit measures 21.5 in. high × 21 in. wide × 16.3 in. deep and weighs approximately 35 lb (15.9 kg) when empty. This compact, almost square-fronted unit fit into the recess with enough clearance to remove the core and filters from the front.
Actual performance at −25°C. This is the point we consider most important for the Montérégie and Haut-Saint-Laurent regions, where periods below −20°C are not unusual.
The technical data we validated before ordering
| Parameter | Value |
|---|---|
| Continuous airflow | 35 to 150 cfm at 0.2 in. w.c.; 35 to 140 cfm at 0.4 in. w.c. |
| SRE at 0°C | 75 % (at 64 cfm) — 66% at 131 cfm |
| SRE at −25°C | 60 % (at 64 cfm) |
| Adjusted SRE at 0°C | 78% (at 64 cfm) |
| Connections | 4 × 5-inch round, top-mounted |
| Motors | PMSM (ECM), two permanent-magnet motors |
| Defrost | By negative pressure (exhaust defrost) |
| Filtration | MERV 8, washable/replacement |
| Certifications | HVI 2100 certified, cUL/UL, ENERGY STAR® (Canada only) |
| Warranty | Limited lifetime on the heat-exchange core |
The ENERGY STAR® designation shown on the unit's bilingual label includes a nuance few clients notice: the certification applies only when the unit is used in Canada, because it is established by Natural Resources Canada according to criteria specific to the Canadian climate. We prefer to explain this rather than let it pass as a simple logo.
The installation: four chains, two rails, and a reason behind every decision
The unit is suspended by chains at all four corners, anchored into the ceiling structure of the recess, and rests on two support angles screwed into furring strips secured to the rear wall. This combination is not redundant: the chains provide vibration isolation and prevent motor noise from being transmitted through the framing; the angles prevent the unit from tipping forward when the door is opened and the core is removed.
The errors we most often correct on installations taken over in Laval, Longueuil, or on the North Shore concern precisely this point:
- A VRC rigidly screwed against a joist. The noise spreads throughout the house. The client lowers the airflow, then eventually shuts the unit off.
- Chains of unequal lengths. The unit tilts, the condensate pan no longer drains toward the intended outlet, and water accumulates at the bottom of the cabinet.
- No clearance at the front. The core cannot be removed. Annual maintenance becomes impossible.
We therefore leveled the unit with a spirit level, in both directions, before permanently securing anything.
The ducts: insulated, short, and sealed in the right places
The four 5-inch fittings exit through the top toward the attic. The two exterior ducts — fresh-air intake and stale-air exhaust — are made of insulated flexible duct with a continuous vapor barrier, which is non-negotiable in a ventilated attic in the Haut-Saint-Laurent: an uninsulated cold-air duct passing through an unheated space produces condensation, which produces mold, which produces a service call two years later.
The two interior ducts — fresh-air distribution and stale-air extraction — serve the heating system's return air and the humid areas (bathroom, kitchen), respectively. Sealing was done with aluminum tape and duct sealant on each male fitting, never with ordinary duct tape, which dries out and peels off within three winters.
The detail clearly shown in the photo: the condensate drains
Under the unit, two drainage tubes descend, join through a T-fitting, and then run to a drain. This setup deserves an explanation because it is often done carelessly.
- Each outlet must have a trap or P-trap loop. Without a trap, the negative pressure generated by the exhaust fan draws air through the drain instead of allowing the water to drain.
- The junction T must be downstream of both traps, never upstream.
- The slope must be continuous. A sag in the flexible tubing retains water, freezes if the room is cold, and blocks drainage at precisely the time of year when the HRV produces the most condensate.
The V150H75NT's exhaust defrost reduces the amount of water compared with recirculation defrost, but does not eliminate it: in January, a properly adjusted 150 cfm HRV produces a clearly visible amount of condensate.
Power supply and controls
The unit is powered by a 120 V cord plugged into a dedicated outlet installed in the recess—not an extension cord and not a lighting circuit. The V150H75NT's PMSM ECM motors consume little power, but a dedicated outlet remains best practice and simplifies isolating the unit during maintenance.
The low-voltage wiring to the wall control was connected with wire caps in the recess, then routed to the backlit control box visible to the left of the unit. This control provides access to the ventilation modes—continuous, intermittent (20/40/60 minutes per hour), and high speed—as well as the diagnostic menus.
Balancing: what Virtuo Air Technology changes in practical terms
On an HRV from an earlier generation, balancing was done with a balometer or manometer, using adjustment plates, a technician, about an hour, and a real margin of error. The Virtuo Air Technology platform incorporates electronic airflow measurement and an LCD screen directly on the unit: the HRV calibrates its two fans itself to achieve a balance between the incoming and outgoing air, then displays the resulting airflow.
This balance is not a theoretical refinement. An unbalanced unit creates:
- a negative pressure, which draws unconditioned air in through cracks, increases the risk of backdrafting from a combustion appliance, and drives up the heating bill;
- a positive pressure, which pushes moist indoor air into the walls and insulation, where it condenses.
In Dundee, calibration was started after the ducts had been fully connected—never before, since the measurement takes into account the actual resistance of the system. Any subsequent modification to the ducts requires the test to be run again, as is also stated clearly on the unit's installation label.
Maintenance: the schedule we leave with the customer
- Every 3 months: remove and wash the MERV 8 filters in warm water, and let them dry completely before reinstalling them.
- Once a year, in the fall: remove the heat-exchange core, vacuum it, and rinse it with warm soapy water without using a high-pressure jet.
- Once a year: check that the drains flow freely and that the traps are primed.
- Twice a year: inspect the exterior hoods (intake and exhaust)—a bird's nest or snow buildup blocks them more often than one might imagine in rural areas.
Programs and rebates: what you need to know before counting on them
We prefer to be precise rather than optimistic. In Quebec, a standalone air exchanger is generally not a measure eligible for direct financial assistance: provincial programs such as Rénoclimat assess the house as a whole and provide assistance for insulation and air-sealing measures, while ventilation is generally treated as an indoor-air-quality requirement associated with this work. The amounts, eligible measures, and conditions change from year to year. We therefore verify eligibility on a case-by-case basis at the time of the quote, rather than promising an amount.
Our service area
This project in Dundee is at the western edge of our service area, but the logic remains identical to what we apply in Montreal, Laval, Longueuil, on the North Shore, and on the South Shore: a unit sized for the home's actual volume, an installation that keeps maintenance possible, an insulated duct system wherever insulation is required, a trapped drain, and balancing that is verified and documented before we leave the site.
What the Dundee installation illustrates about residential ventilation in Quebec
The choice of the vänEE AI Series V150H75NT was not dictated by a specification sheet read in isolation, but by the combination of a physical constraint—24 inches of depth and no side clearance—and a climate that requires an ERV of 60% at −25 °C as an acceptable minimum. The top ports, PMSM ECM motors, exhaust defrost, and Virtuo Air Technology self-balancing form a coherent package for this specific case.
In a house with a clear mechanical room in Brossard or Terrebonne, our recommendation might have been a model with side ports or a higher airflow rate. The house determines the unit, never the other way around. To assess your need for HVAC installation or HVAC maintenance, our team visits the site and takes measurements before proposing anything.