Too much indoor humidity can turn your home into a tropical greenhouse—even in the middle of winter. Persistent odors, condensation on windows, heavy or stuffy air… These familiar signs often point to an issue with your heat recovery ventilator, or more precisely, a poorly calibrated HRV. At AirGreen, specialists in HVAC in Montréal, Laval, Longueuil, North Shore and South Shore, we regularly meet clients dealing with these problems. The good news? In most cases, a simple adjustment to the airflow of the HRV is enough to restore a healthy and comfortable balance.
Excessive Humidity: Underestimated Consequences
Impacts on Health and Comfort
An indoor relative humidity above 50% can promote the growth of mold, dust mites, and bacteria. The result: allergies, respiratory irritation, and constant discomfort. This is especially common in modern homes—better insulated but often poorly ventilated—particularly in winter when windows stay shut.
Damage to the Building
Excess moisture attacks walls, ceilings, and windows. Peeling paint, swollen wood, mold in the corners… All clear warning signs. They not only indicate an imbalance in your indoor air, but also deficient ventilation that could eventually lead to expensive repairs.
The Central Role of the HRV: Ventilation and Humidity Control
An HRV (heat recovery ventilator) is a smart system designed to ensure constant renewal of indoor air while recovering heat. It removes stale, humid air (bathrooms, kitchens) and replaces it with filtered outdoor air, while minimizing energy loss.
But for the system to perform optimally, it needs to be properly balanced. A poorly calibrated HRV—too much air coming in, not enough being extracted—can completely throw off your indoor humidity levels.
Why Your HRV Is Probably Poorly Calibrated
Common Problem: Airflow Imbalance
One of the most frequent issues we see: the HRV brings in more air than it extracts. This leads to a gradual buildup of humidity, especially in high-moisture areas like bathrooms, kitchens, and laundry rooms. The imbalance may stem from poor initial calibration, clogged filters, or a faulty installation.
Installation or Configuration Errors
We recently responded to a call at a home in Boucherville (South Shore), where the client complained about constant window fog starting in October. Upon inspection, we discovered the HRV was only connected to the living room and bedrooms—no extraction in humid areas. Result: no moisture removal. We modified the ductwork, adjusted the airflow rates, and rebalanced the system. Within days, humidity levels dropped back below 45%.
How to Check if Your HRV Is Poorly Calibrated
Symptoms to Watch For
Here are the warning signs:
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Frequent condensation on windows
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Stale odors despite regular airing
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Moist or muggy air
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Humidity above 50% (use a hygrometer to verify)
Simple Tests You Can Do Yourself
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Toilet Paper Test: Hold a sheet of toilet paper up to an exhaust vent (bathroom, kitchen). If it doesn’t stick or move, the extraction is too weak.
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Hygrometer: Place a hygrometer on each floor of the home and track fluctuations. If humidity is stagnant or rising, your ventilation system likely has an issue.
What to Do If Your HRV Is Poorly Calibrated
The Importance of Professional Rebalancing
HRV rebalancing involves measuring incoming and outgoing airflow with specialized tools (balometer, anemometer), then adjusting fan speeds or manual dampers to achieve perfect balance. At AirGreen, our certified technicians carry out these operations with precision—often in under two hours.
Cleaning and Maintenance
A neglected HRV collects dust, mold, and debris, drastically reducing its performance. It’s essential to:
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Clean or replace filters every 3 to 6 months
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Inspect ducts to ensure they're not blocked
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Dust the heat exchanger at least once a year
Customer Testimonial: When a Simple Adjustment Changes Everything
In Laval, a family called us about persistent humidity despite having a new HRV. After our analysis, we found the system was bringing in more air than it was extracting. By adjusting the fan speeds, we quickly corrected the imbalance. The result: stabilized humidity at 42%, dry windows in the morning, and noticeably better air quality.
Common Mistakes to Avoid with HRVs
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Never fully close the exhaust vents
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Don’t turn off the HRV to “save energy”
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Never connect an HRV without consulting an HVAC installation expert
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Always have your system inspected and adjusted after major renovations
Why Choose AirGreen to Adjust Your HRV
At AirGreen, we understand every home is different. That’s why we tailor our service to each layout, insulation level, occupancy, and lifestyle. Our specialists in residential and commercial ventilation operate across Montréal, Laval, Longueuil, North Shore and South Shore, diagnosing, adjusting, cleaning, and optimizing your central ventilation systems.
We use professional-grade equipment, certified technicians, and deliver service that is fast, transparent, and long-lasting. Our goal: ensure your indoor air quality is as healthy as it is comfortable—all year long.
Key Tips to Remember
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Regularly measure your home’s humidity
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Have your HRV checked at least once a year
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Clean filters with each seasonal change
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Rebalance your HRV after any home renovation
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When in doubt, call our experts for a complete HVAC ventilation diagnosis
Good Ventilation Starts with Proper Calibration
A poorly adjusted HRV can turn a high-performance ventilation system into a source of discomfort. When your unit is properly calibrated, you protect both your health and your home. At AirGreen, we guide you every step of the way to guarantee balanced and efficient ventilation, perfectly adapted to your environment.
Contact us today for a complete evaluation of your HRV or to schedule a professional rebalancing of your ventilation system.