Understanding the Hidden Dangers to Better Protect Your Health and Home
In the field of HVAC for residential and commercial spaces in Montreal, Laval, Longueuil, the North Shore, and the South Shore, one of the most overlooked yet potentially hazardous issues is undoubtedly the presence of mold in ventilation systems. Too often, this problem remains unseen until symptoms appear: allergies, persistent odors, excessive humidity, or even chronic respiratory issues. At AirGreen, our daily experience in maintenance and installation of air exchangers has taught us one thing: what you don’t see can seriously harm your comfort, your health, and even the integrity of your property.
Why Does Mold Develop in a Ventilation System?
Moisture is the primary trigger for mold growth. In an improperly designed, poorly maintained, or obstructed ventilation system, moisture can stagnate in the ducts. This can come from several sources:
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Moist air infiltration from the outside (especially in areas like basements or bathrooms).
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Lack of proper ventilation in high-humidity areas.
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Condensation in poorly insulated air ducts.
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An improperly calibrated or malfunctioning air exchanger.
Mold will then develop on the internal surfaces of the ducts, in filters, or on the mechanical components of the air exchanger.
What We Often See in the Field
At AirGreen, we regularly work in homes across Laval, Longueuil, and even Saint-Eustache, where clients contact us for odor issues, allergic reactions, or stale air, never suspecting mold. In a recent case in Boucherville, an air exchanger from Zehnder installed over 8 years ago had never been maintained. The result: established mold colonies, which had contaminated the entire duct system.
Signs That Should Raise Red Flags
Even if mold is invisible, certain signs are clear indicators:
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Persistent, slightly earthy odor in the house.
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Black or greenish stains visible on ventilation grilles.
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Excessive condensation on windows.
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Worsening of allergy symptoms or asthma.
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Discolored or deteriorated air exchanger filter.
If you live in Laval, Repentigny, or Saint-Hubert, where humidity is higher during the winter and spring, be especially vigilant.
The Health Impact
Ignoring mold in a ventilation system means exposing the occupants to an unhealthy environment, continuously. Contaminated air circulates and redistributes mold spores throughout the house. This can lead to:
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Chronic allergic reactions (coughing, sneezing, nasal congestion).
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Respiratory problems for sensitive individuals, including children and the elderly.
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Worsening of asthma and other lung diseases.
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Chronic fatigue or unexplained headaches.
What We Do Differently at AirGreen
We don’t just clean — we diagnose and address the root of the problem. Here’s our typical approach when handling a mold issue:
Comprehensive HVAC System Inspection
Using specialized cameras, we inspect the inside of the ducts to locate the affected areas. We also evaluate the performance of your air exchanger (HRV or ERV), its calibration, and the condition of the filters.
Professional Cleaning and Decontamination
We use approved products and HEPA equipment to remove mold without releasing spores back into the air. Every duct is thoroughly cleaned, including the return vents and internal fans.
Customized Recommendations
We analyze your ventilation habits, indoor humidity levels, and the overall state of your insulation. This allows us to recommend practical solutions, such as adding a dehumidifier, calibrating the airflow, or replacing the air exchanger with a more efficient model, like the Venmar AVS or Broan AI units available at AirGreen.
Tips to Prevent Mold Long-Term
1. Maintain Your Air Exchanger Twice a Year
The filter should be checked every three months. Professional HVAC maintenance is recommended in both spring and fall.
2. Control Indoor Humidity
Keep levels between 35% and 50%, especially during winter. Too low, and you risk irritation; too high, and mold thrives.
3. Never Block or Obstruct Air Inlets or Outlets
This disrupts the system and encourages stagnant moist air.
4. Invest in a Quality Air Exchanger
We recommend heat recovery ventilators (HRVs) or energy recovery ventilators (ERVs), specifically suited to the Quebec climate. These systems ensure optimal air renewal while reducing heat loss.
Case Study: Intervention in Longueuil – A Game Changer
A client from Longueuil recently contacted us after noticing odor issues in their bedrooms. We discovered significant mold buildup in the ducts leading to the upstairs rooms, caused by poor initial installation of their air exchanger. Our team replaced the unit with a Broan ERV 250, recalibrated the entire ventilation system, installed a smart humidity sensor, and performed a full network cleaning. The result: immediate improvement in air quality and a client who can now sleep soundly.
Conclusion: What You Don’t Know Can Really Hurt You
Mold in ventilation systems is much more than a mere inconvenience: it’s a real health risk, silent and insidious. At AirGreen, we have the expertise, the tools, and the approach needed to effectively identify, address, and prevent this issue. Don’t let the invisible harm your comfort: request a professional inspection of your ventilation system today.