A country house sealed too tightly: the Franklin project, told from the inside
Franklin is the countryside of the Haut-Saint-Laurent: orchards on the slopes of Covey Hill, quiet country roads toward Rockburn and Herdman, and many older homes that have been carefully renovated over the past twenty years. This is exactly the type of building that brought us to this client: an expanded bungalow insulated with spray foam during a roof renovation, with replacement windows and new weatherstripping. On paper, an energy-efficiency success. In reality, a house that could no longer breathe.
The first call came in late fall. The symptoms described by the homeowner were the same ones we hear every year on the South Shore and the North Shore: condensation running down the bottom of the windows as soon as the mercury drops below -10 °C, a cooking smell that lingers until the next day, and two upstairs bedrooms where occupants woke up with heavy heads. Nothing was broken. The building was simply doing what an airtight building does when no one provides it with mechanical fresh air.
The diagnosis before proposing anything
At AirGreen, we do not sell an air exchanger based on a description given over the phone. Our technician came equipped with a hygrometer and a manometer and spent an hour documenting the house before discussing equipment.
What he found:
- Indoor relative humidity of 58% to 61% during the day, while the winter target in Quebec is between 30% and 40%, depending on the outdoor temperature.
- No continuous mechanical ventilation. Two bathroom fans, one of them disconnected in the attic, and a recirculating range hood—which means it exhausts nothing from the house.
- A basement dryer and a combustion fireplace: two appliances that draw air and increase the depressurization of an airtight house.
- Early signs of mold in the northeast corner of the primary bedroom, where the corner wall is coldest.
The conclusion was clear: the building produced more water vapor than its envelope could expel through infiltration. This is the classic scenario of a renovated house without ventilation. Adding a dehumidifier would have concealed the condensation without ever replacing the air. What was needed was a heat recovery ventilator.
Why we chose the vänEE 100H for this house
Choosing an air exchanger isn’t about the listed price, but about three figures: available airflow, recovery efficiency, and the power consumption of the unit that will run 24 hours a day, 365 days a year.
The vänEE 100H checked all three boxes for this floor area:
| Feature | vänEE 100H (No. 1601706) |
|---|---|
| Airflow | 66 to 150 cfm (at 0.4 in. w.g.) |
| Apparent sensible effectiveness at 0 °C | 79 % (low speed) |
| Power consumption | 67 W on low speed |
| Connection diameter | 6 in (15 cm), on the sides |
| Dimensions | 42 cm H × 89 cm W × 43.5 cm D |
| Weight | 29.5 kg |
| Certifications | ENERGY STAR, HVI-certified, and cUL |
The decisive point is the 79% apparent sensible effectiveness at 0 °C. In practical terms, the unit recovers nearly four-fifths of the heat from the stale air it exhausts to preheat the fresh air entering the home. In Franklin, where January nights regularly drop below -25 °C, this recovery is the difference between comfortable ventilation and a cold draft that the client ends up unplugging after three weeks.
HRV or ERV: the question that must be settled in the right place
We often hear the same hesitation, in Montreal, Laval, and Longueuil: should you choose an HRV (heat recovery ventilator) or an ERV (energy recovery ventilator, which also transfers moisture)?
Our position, backed by hundreds of projects in Quebec’s climate: in a house whose winter problem is excess humidity, an HRV is the right tool. An ERV returns some of the water vapor indoors, which is useful in an overly dry dwelling—a downtown high-rise condo, for example—but counterproductive in a country house where people cook, dry laundry, and heat with wood. Here, the 100H in HRV configuration was the unit that addressed the actual issue.
The real challenge of this project: installing it in the attic
The house had neither a finished basement nor a mechanical room. The only available space was the utility space built beneath the roof, above the attached garage—a 2x-framed area with OSB decking, accessible through a hatch. That’s where the 100H was installed, and this is where the details that make the difference between a fifteen-year installation and one that freezes during the first hard cold snap come into play.
1. Suspension: chains and springs, never screws directly into the joist
The unit is suspended from the joists using the supplied chain-and-spring kit. The springs decouple the unit from the framing and prevent the motor's hum from being transmitted to the ceiling of the bedroom below. Screw it directly into the wood, and the client hears the air exchanger from their bed. We also checked the unit's level in both axes: a tilted cabinet means the condensate pan will not drain.
2. Two duct families, two different treatments
This is the technical detail most homeowners overlook, and it is visible in the job-site photos.
- The exterior ducts—the fresh-air intake and stale-air exhaust that run through the attic to the wall hoods—are fully insulated and vapor-sealed. They carry air at -25 °C in winter and warm, humid air in summer. A bare duct in that location means condensation dripping onto the ceiling insulation, followed by a brown stain on the drywall in spring.
- The short interior duct connecting the unit to the home's ductwork, on the other hand, is made of uninsulated semi-rigid aluminum. It carries only room-temperature air: insulating it would add nothing, and the semi-rigid duct allows for a clean tight bend in a space where every inch counts.
We regularly see the opposite on installations taken over in Saint-Chrysostome, Ormstown, or Hemmingford: the entire system made of cheap insulated flex duct, crushed between two joists, with such a pressure drop that the unit never delivers its advertised airflow.
3. The condensate drain, the number-one enemy in an attic
A HRV produces water. A lot of it in January. In an unheated space, a poorly designed drain freezes, water backs up into the unit, and the motor eventually fails. We connected the built-in “snap-in” drain on the 100H to a filled trap, then routed the line as directly as possible toward a heated space, with a continuous slope and no horizontal section where water could become trapped. The exposed section was insulated along its entire length.
4. Service access, planned from the very first sketch
The unit's access door opens toward the front. We therefore positioned the cabinet to maintain full clearance in front of the door, with an OSB service platform installed over the joists and a light nearby. The client must be able to remove the interior filters and core without acrobatics. An installation that cannot be serviced becomes, in practice, an installation that is not serviced.
5. Exterior wall caps: distance, orientation, and snow clearance
The two wall caps were installed more than 1.8 m apart to prevent the expelled stale air from being immediately drawn back in through the fresh-air intake. They were placed on the sheltered side, away from the prevailing winds, at a safe distance from the dryer vent and range hood exhaust, and most importantly, high enough above the ground — in rural areas such as Franklin, a three-foot accumulation of snow against a north-facing wall is nothing unusual, and a buried air intake is useless.
Balancing: the step too many installers skip
An air exchanger must expel exactly as much air as it introduces. That's the basic rule, and it's also the one we most often find neglected during our inspections.
The 100H is equipped with integrated pressure ports and balancing dampers. Our technician connected his manometer to both ports, compared the readings with the manufacturer's performance curves, and then adjusted the dampers until the intake and exhaust airflow rates were identical.
Without this step:
- A negative imbalance depressurizes the house. Air infiltrates through the walls, moisture migrates into the insulation, and above all, a combustion appliance — the client's fireplace, in this case — is at risk of combustion-gas backdrafting. This is not a comfort issue; it is a safety issue.
- A positive imbalance pushes warm, humid air from the house into the wall cavities, where it condenses against the cold siding.
The balancing was documented in writing and provided to the client along with the measured airflow rates. We do the same thing for every HVAC installation in the ventilation system, from Montreal to the far reaches of the South Shore.
What this project reminds us of, and what we apply throughout Greater Montreal
Six weeks after commissioning, the home's relative humidity stabilized between 34% and 38% during the cold season. The windows remained dry during the first cold snap in January. The homeowner particularly noticed one detail she had not expected: the musty smell that used to greet her when she came home from work had disappeared.
The mistakes we correct most often
Here, in order of frequency, is what we find when reworking existing installations:
- No balancing performed. The dampers remained in their factory positions, and the unit has been operating out of balance for ten years.
- Uninsulated exterior ducts in an attic or crawl space.
- Exterior hoods installed too close together, causing direct recirculation of stale air.
- Dryer or range hood connected to the air exchanger. Lint and grease destroy the core. These two appliances require dedicated exhaust systems.
- Excessive lengths of flexible duct, with sagging between supports.
- Indoor filters never cleaned. This is the number one cause of reduced airflow that we measure in the field.
- Improperly configured wall control, left in “intermittent” mode when the house would require continuous operation at low speed.
Applicable subsidies in Quebec
The Quebec government's Rénoclimat program provides financial assistance for installing or replacing a heat recovery ventilator (HRV) or an ERV, in the amount of approximately $500, provided that the unit appears in section 3 of the Home Ventilating Institute (HVI) certified products directory—which is the case for the Bronze series vänEE models, including the 100H.
Two practical conditions to know before planning your work:
- The assistance requires a pre-work energy assessment and a post-work assessment by a recognized advisor. The initial assessment must be completed before work begins; otherwise, the application will be refused.
- Program amounts and criteria are reviewed periodically. We systematically confirm eligibility with the customer when the application is submitted rather than promising an amount blindly.
Our administrative team assists clients with preparing their applications, whether in Franklin and the Haut-Saint-Laurent area, or in Laval, Longueuil, or on the North Shore.
Maintenance: fifteen minutes, three times a year
A well-maintained air exchanger preserves its airflow and efficiency. The schedule we provide to our clients is simple:
- Every 3 months: remove and wash the interior filters in warm, soapy water, and let them dry completely before reinstalling them.
- Once a year: remove and rinse the recovery core, check the drain trap and the condition of the suspension straps.
- Twice a year: inspect the exterior hoods and remove leaves, insect nests, and accumulated ice.
- Every 2 to 3 years: have the airflow balance checked, especially if work has modified the duct network.
Why entrust your ventilation to AirGreen
We have been installing ventilation, heating, and air conditioning systems in Greater Montreal for years, with more than fifteen teams on the road and a fleet of trucks covering Montreal, Laval, Longueuil, the North Shore, the South Shore, and all of Montérégie, reaching rural municipalities such as Franklin, Hemmingford, Ormstown, and Saint-Chrysostome.
What we bring to a residential ventilation project:
- A measured diagnosis before making a recommendation, not a visual estimate.
- Sizing based on floor area and number of bedrooms, in accordance with current ventilation requirements.
- A documented air balancing report provided to the client, with actual airflow rates.
- A team holding an RBQ licence and providing comprehensive assistance with subsidy applications.
- A HVAC maintenance and repair service for years to come, for the brands we install as well as those we inherit.
If your home shows condensation on the windows, lingering odors, or stuffy air in the morning, these signs deserve measurement rather than guesswork. Contact us: we come to your home, take measurements, and explain exactly what your building needs — even if the answer is that it needs nothing.