A row house, a damp basement, and an air exchanger finally installed properly
Godmanchester is the kind of municipality where houses are half a kilometre apart, the wind sweeps across the fields unhindered, and almost every basement contains a wood stove. It is also the kind of place where mechanical ventilation is treated as an accessory, even though it has become the central link in indoor comfort since homes were tightened up.
The homeowner called us in February. His description came down to three observations: the bedroom windows ran with condensation every morning, the basement subfloor smelled musty despite a dehumidifier running nonstop, and cooking odours took half a day to disappear. A single-storey home from the 1980s, approximately 1,400 sq. ft., renovated in 2016 with spray foam in the rim joists and new windows. The building envelope had been tightened. The ventilation, however, had remained in 1980.
The diagnosis: a sound unit, but an improper installation
The air exchanger was already there. A vänEE 90H, in good mechanical condition, but installed in a way that prevented it from ever delivering its rated performance.
What we found on site:
- Crushed flexible ducts for nearly three metres, pinched between a joist and a plumbing pipe. A flexible duct bent at 90 degrees can lose more than half its airflow.
- No balancing had been performed. The pressure taps had never been used: the plugs were still factory-sealed.
- No condensate drain, replaced by a bucket. On an HRV, condensate is not optional: the core produces it whenever warm stale air meets cold outdoor air.
- Unit screwed directly into the joists, without chains or springs. All the motor vibration was transmitted to the kitchen floor.
- Outdoor exhaust hood blocked by frost due to insufficient clearance above the snow line.
The unit was not at fault. The installation was. This is something we regularly see in Montreal and Laval, as well as on the North Shore, the South Shore, and in the rural areas of Montérégie.
Why choose an HRV rather than an ERV in Haut-Saint-Laurent
The distinction is poorly understood, yet it determines comfort for six months of the year.
An HRV (heat recovery ventilator) transfers heat from outgoing stale air to incoming fresh air without transferring humidity. An ERV (energy recovery ventilator) also transfers some of the humidity.
In a Godmanchester home partly heated with wood, with a partially buried basement and a well, excess indoor humidity in winter is the variable to control. An ERV would return some of that humidity indoors—the exact opposite of the desired result. An HRV is therefore the right choice in the vast majority of homes in southwestern Montérégie.
The reasoning is reversed in an air-conditioned downtown Montreal tower, where the air becomes too dry in January and an ERV is a very good option. The local climate and heating method are decisive, not the technical specifications alone.
The vänEE 90H in detail
The 90H belongs to vänEE's generation of HRVs with galvanized-steel cabinets. vänEE is an HVI-certified manufacturer and a member of HRAI. Its key installation features include:
- Removable and washable cross-flow countercurrent heat-recovery core.
- Washable interior filters on either side of the core.
- 6-inch double collars for outdoor connections, with balancing collars equipped with pressure taps on the house side.
- Thermistor-controlled motorized defrost damper: below a certain outdoor temperature, the unit periodically stops drawing in fresh air and recirculates indoor air to defrost the core.
- Drain connection for condensate drainage.
- Door switch that shuts off the unit as soon as the panel is opened.
- Chain-and-spring installation kit for vibration-isolating suspension.
A service detail few people know about
On the 90H and 190H, parts are not ordered according to the model, but according to the serial number prefix. CR… and CS… units do not use the same components as 7R…, 9R…, 7S… and 9S… units. The core, for example, is part 03322 on some series and 02507 on others. The electronic board changes from 13029 to 13034 depending on the serial-number range. Even the filter changes: 02300 or 02349, with one or two filters depending on the number.
This is precisely why we systematically photograph the nameplate before leaving a job site. A technician who arrives with the wrong part means a second visit billed to the customer. At AirGreen, this record is part of the installation file.
The installation process
The work took a full day, with two technicians.
- Complete removal and cleaning of the unit. Core washed with warm soapy water, interior filters scrubbed, cabinet dusted, and blower wheels cleaned. A dirty core loses its recovery efficiency before it loses airflow.
- New suspension. Chains and springs secured to two separate joists, with the unit leveled using a bubble level. Leveling is not cosmetic: it determines how condensate flows toward the drain connection.
- 6-inch galvanized rigid-duct system. We replaced the crushed flexible sections with rigid ducting, using long-radius elbows and joints sealed with mastic, then covered with aluminum tape. Insulated flexible ducting was retained only on the short sections leading to the exterior penetrations, where the insulation prevents condensation on the duct wall.
- Restoration of the two wall penetrations. Exterior hoods repositioned with a minimum separation of 1.8 m (6 ft) between the fresh-air intake and the exhaust, and raised high enough to clear the typical snow level during a Haut-Saint-Laurent winter. Rodent screens checked on both.
- Condensate drain connected to the floor drain, with a trap and a continuous slope.
- Power supply connected to a dedicated outlet, with the cord clear of the cabinet's sharp edges.
- Wall control installed on the main floor, with programmed intermittent mode and a dehumidistat override.
- Final balancing.
Balancing: the step that separates an installation from a hookup
An unbalanced air exchanger creates negative or positive pressure in the house. Under negative pressure, air infiltrates through cracks, the heating bill increases, and above all, a combustion appliance can backdraft. In a house with a wood stove, this is not merely theoretical.
We balance the system with a differential manometer at the original pressure taps until the supply and exhaust are within a 10% difference, in accordance with the approach of the CSA F326 standard. The measured airflow rates are recorded on a label affixed inside the unit door, along with the date. The next technician will know where to start.
The mistakes we see most often
- Connect the exhaust to the dryer or range hood. Never. Grease and lint destroy the core.
- Use uninsulated flexible ducting for outdoor sections: condensation builds up in the folds and eventually drips into the ceiling insulation.
- Install exhaust grilles anywhere other than in humid rooms. Bathrooms, laundry rooms, and kitchens: that is where stale air should be extracted.
- Forget about the drain trap, allowing the unit to draw air from the floor drain.
- Set the unit to run continuously at high speed all winter, which dries out the house and unnecessarily increases energy consumption. Programmed intermittent mode produces better results.
Maintenance: three tasks, three frequencies
- Indoor filters: wash with lukewarm water every 2 to 3 months. More often if you have pets.
- Core: remove and wash once a year, ideally in the fall before the heating season.
- Outdoor hoods: inspect twice a year. In rural areas, the screens become clogged with seeds, insects, and powdery snow.
Grants and compliance: what is true in 2026
Let's be precise, because many articles cause confusion. Residential air exchangers are not eligible for direct financial assistance under current Quebec programs intended for existing homes. What ventilation does influence, however:
- In Novoclimat-certified new construction, a heat-recovery ventilation system meeting the program's criteria is required. The air exchanger is an integral part of the certification.
- As part of a Rénoclimat evaluation, the building envelope's airtightness is measured. The more airtight the building, the more necessary mechanical ventilation becomes to maintain air quality. These two projects should be planned together.
- The Quebec Construction Code requires mechanical ventilation in new homes, with airflow rates calculated room by room.
We verify eligibility on a case-by-case basis before the work begins, rather than promising amounts that do not exist.
What Godmanchester Reminds Us About Ventilation in Rural Montérégie
Homes in Haut-Saint-Laurent present constraints that we do not encounter in a Longueuil condo: long duct runs through unheated crawl spaces, combustion appliances in operation, more frequent power outages, and local wildlife that finds outdoor exhaust hoods very inviting. Each of these factors affects the duct layout, the choice of materials, and the final adjustment.
We use the same method everywhere we install air exchangers: a complete assessment, airflow calculations, rigid ducts whenever the configuration allows, documented balancing, and a file provided to the customer. This applies in Montreal, Laval, Longueuil, on the North Shore, on the South Shore, in Salaberry-de-Valleyfield, Huntingdon, and Ormstown.
Let's talk about your home
If your windows leak in January, your basement smells musty despite using a dehumidifier, or your air exchanger has never been balanced since it was installed, the unit is probably not the problem. We come to your home, take measurements, and provide you with a quantified assessment before proposing anything.
AirGreen — Air conditioning, heating and ventilation. RBQ 5645-9605-01. (514) 316-2973 | sales@airgreen.ca