What your ventilation system hides might surprise you — and it’s our job to uncover it.
At AirGreen, we carry out hundreds of ventilation inspections every year across Montréal, Laval, Longueuil, the North Shore and South Shore, and sometimes, what we find behind the walls goes far beyond expectations. Far from being routine technical checks, these inspections often uncover unusual situations — some funny, some serious — but all are proof of how vital regular HVAC maintenance and a professional eye really are.
Here are three real-life stories taken straight from our daily work with ventilation systems. These anecdotes highlight the hidden risks of poorly maintained or improperly designed ductwork and show the true value of regular inspections carried out by seasoned technicians.
A Nest of Life Beneath the Air Vents
📍 Location: Laval – Single-family home, built in 1990
During an inspection in a family home in Laval, our technician noticed a slight musty smell near the return air vents in the basement. When he removed the grille, he discovered a perfectly built mouse nest tucked inside the duct.
What the homeowner thought was just an annoying draft turned out to be caused by a blockage of debris and nesting material. Even more concerning: airflow throughout the network had been disrupted, causing increased energy consumption from the central heating system.
Our solution:
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Full removal of the nest and disinfection of the duct system
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Installation of anti-intrusion mesh on exterior air intakes
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Full check of the air exchanger to detect any moisture-related damage
AirGreen Tip: Have your ducts inspected every 3 to 5 years, even if no visible issues are present. Small animals can easily sneak in through poorly protected outdoor vents, especially in the fall.
Hidden Mold, Real Consequences
📍 Location: Longueuil – Duplex with a 12-year-old air exchanger
A duplex owner in Longueuil called us about a lingering odor in the ground-floor unit. At first glance, the ventilation system seemed to be working. But a camera inspection inside the ducts revealed significant growth of black mold, invisible from the outside but deeply embedded in the metal surfaces.
This contamination stemmed from an air exchanger whose filters hadn’t been changed once since installation — twelve years ago. Humidity in the home had condensed inside the ducts, creating the perfect breeding ground for harmful mold.
Our solution:
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Full duct cleaning using our negative-pressure equipment
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Replacement of the old air exchanger with a Fantech VHR 150R model, certified for homes up to 2,500 sq. ft.
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Personalized seasonal maintenance plan (filter replacement, airflow checks)
Immediate results: Indoor air returned to healthy levels, the smell disappeared within 48 hours, and the client called us back to schedule annual maintenance.
A Fake Air Vent… Leading Nowhere
📍 Location: North Shore – New home, recent HVAC installation
On the North Shore, a young couple who had just moved into a new home reached out to us for a second opinion. They felt their Venmar air exchanger wasn’t delivering fresh air to the main living areas. During our inspection, we discovered that one of the air supply grilles was completely fake — the duct behind it wasn’t connected to anything at all.
This type of construction defect can have serious consequences:
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Uneven airflow
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Overloaded air exchanger motor
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Increased energy consumption
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Significant drop in indoor air quality
Our solution:
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Complete ductwork tracing using our inspection equipment
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Connection of the air grille to a new insulated rigid duct
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Full system balancing to ensure even ventilation across all rooms
Important note: Even newly built homes can contain installation errors or oversights. An independent post-construction inspection is key to ensuring your system runs at its best.
Why These Stories Matter to You Too
Every home, every residential or commercial ventilation system, has its own hidden story behind the walls. Without a thorough inspection, those stories can turn into costly problems — unseen but very real.
At AirGreen, we operate throughout Montréal, Laval, Longueuil, the North Shore and South Shore, with a proven inspection protocol and state-of-the-art equipment. Our approach goes far beyond a basic technical check: we analyze, detect, explain, and fix.
How to Know When It’s Time for an Inspection
Watch out for these warning signs:
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Persistent odors (mold, humidity)
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Excess dust despite regular cleaning
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Respiratory issues or allergies
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Noisy central fan or air exchanger
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Uneven airflow from room to room
AirGreen: Your Ventilation Inspection Experts in Greater Montréal
Whether you’re a homeowner, building manager, or real estate developer, we support you at every step:
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Detailed inspection with a full report
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Performance analysis of your ventilation system
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Personalized recommendations to improve air quality and reduce energy costs
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Preventive HVAC maintenance to avoid major repairs
We believe a proper ventilation system is your first line of defense against indoor pollutants. That’s why our technicians approach every inspection with rigor, expertise, and transparency.
The Bottom Line: A Ventilation Inspection Is Not a Luxury — It’s an Investment
Maintaining mechanical ventilation systems is essential to ensuring your home’s comfort, safety, and health. The stories above are not the exception — they’re more common than you’d think. Behind your walls may lie challenges that only a trained expert can identify.
Trust AirGreen to inspect, optimize, and maintain your ventilation systems with the same care and precision we’d bring to our own homes.