Installation of a Broan-NuTone V150H75NS air exchanger (AI series, Virtuo technology) in Rigaud, in Vaudreuil-Soulanges

A home without a duct network: why a fully dedicated duct network remains the best solution at the foot of Mount Rigaud

Homes in Rigaud present a problem that HVAC installation contractors know well: a significant portion of the housing stock has never had a duct network. Electric baseboard heating, a wood stove in the basement or living room, and sometimes radiant flooring in an addition. No ducts, no plenum, and no central fan to connect to.

This reality completely changes the design of a ventilation system. It also explains why so many homeowners in the area postpone the project: they believe all the ceilings have to be opened up. That is not the case when the basement is unfinished or partially finished, as in the project described here.

We installed a Broan-NuTone V150H75NS there, a heat-recovery ventilator from the AI series equipped with Virtuo technology, suspended by chains in the joist cavity, with a fully dedicated duct network made of insulated flexible ductwork. The unit was commissioned at a flow rate of approximately 65 CFM, with a measured difference of two cubic feet per minute between intake and exhaust.

The context: what we found on site

The house showed the usual signs of an airtight envelope without mechanical ventilation: persistent condensation on the north-facing windows, basement odors rising to the upper floor, and a bathroom whose exhaust fan, the only device in place, merely created negative pressure in a house that did not need it.

The basement, however, offered a decisive advantage: exposed joists over almost the entire area, with enough clearance to run insulated ductwork from one end of the house to the other. This made a fully dedicated duct network possible without demolition work.

The wood stove factor, which must be addressed before choosing the appliance

One out of every two homes in Rigaud has a combustion appliance: a wood stove, an insert fireplace, or sometimes a supplemental furnace. This detail is not incidental; it determines the system configuration.

An improperly balanced ventilation system puts the house under negative pressure. A house under negative pressure draws replacement air through the easiest path, which is often the wood stove chimney. The result is a backdraft of smoke and carbon monoxide.

That is why we systematically reject exhaust-only setups in a wood-heated home, and why balancing the two airflows is not an engineering refinement but a safety issue. A properly balanced HRV introduces as much air as it exhausts: indoor pressure remains neutral, and the chimney draft is not disturbed.

The Broan-NuTone V150H75NS in detail

• Type: heat recovery ventilator (HRV), AI series with Virtuo technology
• Adjustable airflow: 35 to 150 CFM, selected on the integrated LCD screen
• Sensible heat recovery efficiency (SHRE): 75% at 0°C (measured at 64 CFM) and 60% at -25°C
• Connections: four 5-inch side ports
• Filtration: MERV 8 (replacement filter SV66133)
• Motors: electronically commutated PMSM (ECM)
• Dimensions: 23.5 in. wide × 19.13 in. high × 16.3 in. deep (approximately 59.7 × 48.6 × 41.4 cm)
• Weight: 35 lb (approximately 15.9 kg)
• Certifications: HVI and cUL/UL
• Warranty : 10 years on the core
• Installation: suspended by chains or wall-mounted on universal brackets, both included

Why the side ports made the difference here

The choice between a unit with top connections and one with side connections is rarely explained in a quote. It should be, because it determines whether the project is feasible.

Top ports require about 30 centimetres of vertical clearance above the unit to accommodate the elbows. In a standard joist cavity, that clearance does not exist.

The V150H75NS's side ports, on the other hand, make it possible to suspend the unit flush with the joists and route all four ducts horizontally, directly along the joist cavity. That is exactly what we see in this installation: the unit hangs from its chains, and the four insulated ducts extend from each side without ever having to rise.

The trade-off is that 5-inch ports, rather than 6-inch ports, require greater attention to the length and cleanliness of the runs. A poorly tensioned section of flex duct costs proportionally more in pressure loss in a 5-inch duct.

What 75% sensible heat recovery efficiency means under Vaudreuil-Soulanges conditions

An efficiency rating means nothing until it is translated into a perceived temperature.

At 0°C, with a home at 21°C, the unit recovers 75% of the difference: fresh air is introduced at approximately 16°C. This temperature range represents most of our heating season, so this is the figure that has the greatest impact on the annual bill.

At -25 °C, the temperature difference to overcome rises to 46 degrees. With 60% ERS, fresh air enters at approximately 3 °C rather than -25 °C. The heating system supplies the remaining few degrees, and the homeowner feels no cold draft at the supply grilles.

The fully dedicated duct network design

Unlike a connection to an existing forced-air duct system, the dedicated network operates independently. It does not rely on a central fan, making it the standard configuration for homes heated by electric baseboards, hot-water heating, or radiant floors.

Its logic is simple and rigorous:

• Exhaust air is drawn from where contaminants originate: bathrooms, the laundry room, the basement, and near the kitchen—but never directly above the stove, where grease would clog the core.
• Supply air is delivered where occupants live and sleep: the living room, family room, and bedrooms.
• The airflow path thus runs throughout the house, from clean rooms to humid rooms, preventing odors from migrating in the opposite direction.

On this job, the entire interior duct network was installed using insulated flexible duct with a vapor barrier in the joist cavity, with the necessary precautions: ducts stretched tight and free of sags, closely spaced supports to prevent sagging between joists, wide bend radii, the vapor barrier closed and sealed with aluminum tape at every connection, and rigid-collar transitions at the unit’s four outlets.

The installation process

1. Suspending the unit from the joists with chains, verifying that it is level on both axes, and ensuring full clearance in front of the service door for future filter and core maintenance.
2. Installation of the four takeoffs on the side outlets, using sealed rigid collars before connecting the flexible duct sections.
3. Interior duct routing through the joist cavity to the exhaust and supply grilles.
4. Exterior penetrations with two separate hoods, spaced apart to prevent exhaust air from being drawn back in, and kept away from the dryer vent and wood-stove chimney.
5. Condensate drain connection with a continuous slope and a water test—an essential requirement for an HRV that produces water every cold day.
6. Electrical power supply from a dedicated 120 V outlet located in the immediate vicinity of the unit.
7. Target airflow selection on the integrated LCD screen, followed by the Virtuo self-balancing sequence.
8. Commissioning verification: the displayed airflow rates stabilized at around 65 CFM supply and 63 CFM exhaust, a difference of three percent. This reading, visible on the display, confirms that the house is neither pressurized nor depressurized.

Commissioning is a deliverable, not a formality

A number displayed on the screen has value only if it is recorded. We give each client the measured airflow readings, the selected setpoint, and the commissioning date. This allows the homeowner to check for themselves, two winters later, whether the unit is still maintaining its airflow rates, and allows the next technician to know where the system was set and why.

Air quality in Rigaud: two points we raise systematically

Basement humidity in areas near the river. Properties located near the Ottawa River have a complicated history with water. An HRV is an excellent tool for controlling winter humidity because it exhausts the moisture produced by occupants. It does not replace a dehumidifier in summer, when outdoor air is more humid than indoor air. We state this clearly in the quote rather than during a service call in July.

Radon. The region's bedrock makes testing worthwhile, and a test is inexpensive. On this point, precision matters: an air exchanger dilutes indoor air and may help reduce a concentration, but it is not a radon mitigation system. The recognized solution remains sub-slab depressurization. A contractor who sells you an HRV while promising to solve a radon problem is selling you a half-measure.

The mistakes we correct most often in flexible duct systems

• Leaving flex duct sagging between two joists. Each sag acts as a drag on airflow and becomes a dust trap.
• Using twenty feet of flex duct where eight would have been enough. The shortest route always wins.
• Crushing the duct against a beam or pipe instead of routing it around the obstruction.
• Not resealing the vapor barrier. The fresh-air duct is cold: an open vapor barrier causes moisture from the room to condense directly on the insulation.
• Placing an exhaust vent above the stove. Grease migrates into the core and fouls it irreversibly.
• Installing the two exterior hoods side by side. The unit eventually draws back in the air it has just expelled.
• Leaving the wood stove out of the equation. This is the mistake with the most serious consequences.

V150H75NS Maintenance

• Every 3 months: check and clean or replace the MERV 8 filters (SV66133). In a wooded area such as Rigaud, the pollen load in spring warrants a shorter interval.
• Every 6 months: remove the core, vacuum it, rinse it with warm soapy water, and let it dry completely before reinstalling it.
• Every 12 months: inspect both outdoor hoods, check the drain flow, and reread the airflow rates shown on the display to compare them with those recorded during commissioning.
• Every fall: lower the humidity setpoint as the outdoor temperature drops.

The HVAC maintenance of the air exchanger is included in the annual service visit for the heat pump or central system, when there is one, avoiding a separate service call.

Regulations and programs

Residential mechanical ventilation in Quebec is governed by the Building Code and the CSA F326 standard, which sets the required total capacity according to the number and type of rooms in a dwelling. New Novoclimat-certified homes require balanced ventilation, for which an HRV is the usual solution.

Financially, an air exchanger is rarely eligible as a standalone piece of equipment. Instead, it is generally considered as part of an overall energy assessment, in which the building envelope's airtightness and ventilation are analyzed together. Programs change regularly, so we verify eligibility with each client when preparing the quote rather than announcing an amount that may no longer exist when the contract is signed.

Have your Broan-NuTone air exchanger installed with AirGreen

We design, install, and maintain residential ventilation systems in Rigaud, Hudson, Saint-Lazare, Sainte-Marthe, Vaudreuil-Dorion, Pointe-Fortune, the West Island, as well as Montreal, Laval, Longueuil, the North Shore, and the South Shore.

Our method does not change from one job site to another. We record the conditioned floor area, the number and type of rooms, the presence of combustion appliances, and the actual basement clearances before recommending a unit. We install short, taut, sealed, and supported ductwork. We commission the system, read the airflow rates, and document them.

For an assessment of your ventilation needs or a quote for a Broan-NuTone air exchanger, contact our team. We come to your home, take measurements, and explain what you are buying before you buy it.