A silent but essential air exchanger that was no longer doing its job properly
In a residence in Laval-des-Rapides, our AirGreen team intervened for a typical but often underestimated problem: a Venmar air exchanger installed in a technical space on the ceiling, connected to several insulated flexible ducts, was no longer ventilating the house as expected. The client had noticed a gradual decline in indoor air quality, a feeling of stagnant air in some rooms, as well as a louder noise than usual near the unit.
This type of HVAC service call requires a precise approach. An air exchanger is not a heat pump, nor an air conditioner, nor a furnace, but it plays a central role in residential comfort, especially in well-insulated homes in Montreal, Laval, Longueuil, the North Shore, and the South Shore. Its goal is simple: to expel stale air, bring in fresh air, control humidity, and maintain healthy circulation without opening windows in the middle of winter.
In this specific case, the device was installed in a confined area, suspended by chains, with flexible ducts around the unit. Access was not ideal but sufficient to perform a complete diagnosis. The visible brand on the device was Venmar, a widely used manufacturer in Quebec for residential ventilation systems.
Symptoms reported by the client
The client contacted us because the air exchanger seemed to be working, but without real effectiveness. This is an important distinction: a device can make noise, turn on its wall control, and give the impression of running, while having greatly reduced air circulation.
The symptoms observed before our arrival were as follows:
- heavier indoor air, especially in the evening;
- light condensation near some windows;
- odors lingering longer in the house;
- vibrating noise near the unit;
- low airflow at the vents;
- intermittent operation that seemed irregular;
- the impression that the system was no longer renewing the air as before.
This kind of situation is common with residential air exchangers that have not been regularly maintained. Filters, the recovery core, motors, internal dampers, ducts, and seals can all contribute to performance loss.
First inspection: access, ducts, and general condition of the unit
Upon arrival, we started with a complete visual inspection of the installation. The Venmar air exchanger was suspended in a technical space with several insulated flexible ducts. The setup indicated a typical installation for a residence where the device is placed outside living areas to reduce perceived noise and facilitate connection to external outlets.
We checked:
- the condition of the metal cabinet;
- the stability of the suspension;
- the duct fittings;
- the hose clamps;
- the presence of visible air leaks;
- access to the service panel;
- the electrical connection;
- the wall control;
- the operation of the fan;
- the condition of the filters and the internal core.
One of the first things observed was the presence of flexible ducts, some of whose fittings had lost part of their seal. On an air exchanger, a leak at a duct may seem minor, but it quickly disrupts the system’s balance. The device can then pull or push air in the wrong place, which reduces overall efficiency and can create poorly ventilated areas.
HVAC diagnosis: a combined problem, not a single failure
After opening the unit and checking the internal components, our diagnosis revealed a set of problems rather than a single failure. This is often the case with HVAC accessories like air exchangers: the system still works, but several small deficiencies add up to cause a noticeable drop in performance.
The main issues identified were:
Dirty filters
The filters showed a significant accumulation of dust. When filters are clogged, the motor has to work harder to move the air. The airflow decreases, noise increases, and air exchange becomes less efficient.
Recovery core to be cleaned
The internal core, which allows heat transfer between outgoing and incoming air, needed cleaning. A dirty core reduces recovery performance and can also contribute to airflow restriction.
Duct fittings to be repaired
Some flexible ducts showed signs of loosening around the connections. We paid special attention to the joints near the device, as these are often the weak points of an installation located in a ceiling or mechanical room.
Vibration transmitted to the structure
Since the unit was suspended, part of the noise came from slight vibration transmitted by the attachments and ducts. A well-installed air exchanger should remain stable but also be isolated as much as possible from elements that can amplify noise.
Airflow imbalance
The system no longer seemed to provide an adequate balance between extracted air and incoming air. An unbalanced air exchanger can create excessive negative or positive pressure in the house, which affects comfort and can worsen humidity problems.
Repair, cleaning, and performance restoration of the air exchanger
Once the diagnosis was confirmed, we proceeded step by step. The goal was not only to get the device running again, as it was already partially functioning, but to restore consistent, quiet, and safe performance.
Cleaning of filters and core
We first removed the filters and the recovery core to perform a complete cleaning. Depending on the type of air exchanger, some cores can be carefully cleaned, while others require more delicate methods to avoid damaging internal surfaces. In this case, the intervention removed accumulated dust and improved air circulation through the device.
An important tip for owners: the filters of a Venmar air exchanger should not be neglected for several seasons. In the greater Montreal area, with humidity variations, urban dust, pollen, and extended heating periods, periodic maintenance is essential.
Motor and fan inspection
We then verified the operation of the motor and fans. The noise observed did not indicate a complete motor failure, but rather a combination of air restriction, vibration, and poorly secured ducts.
We checked:
- the fan rotation;
- friction noises;
- signs of overheating;
- the general condition of the connections;
- the device's response to commands;
- the stability of operation in different modes.
No major anomaly justified the immediate replacement of the motor. This conclusion is important because it saved the client from a more costly repair. At AirGreen, we always prioritize a thorough technical analysis before recommending the replacement of a part.
Repairing connections and improving sealing
Duct connections were tightened and areas with air leaks were corrected with materials suitable for this type of installation. In a ventilation system, duct sealing is as important as the condition of the device itself. An excellent air exchanger connected to poorly sealed ducts will always yield disappointing results.
We paid special attention to insulated ducts, as a poor joint can cause:
- loss of airflow;
- condensation;
- air noise;
- uncontrolled air infiltration;
- reduced energy efficiency;
- discomfort in certain areas of the house.
Vibration reduction
Part of the intervention also involved stabilizing the unit and reducing vibrations transmitted to the structure. In a technical ceiling, a small noise can travel farther than expected, especially if flexible ducts touch joists, panels, or other mechanical components.
We adjusted some support points, checked the suspension, and slightly repositioned sections of ducts to limit unnecessary contact. The result was immediate: the operation of the air exchanger became quieter.
Checking the wall control and ventilation modes
An air exchanger can be controlled by different types of controls: timer, humidistat, wall button, digital panel, or integrated control within a larger system. In this case, we checked that the controls responded correctly and that the ventilation modes were consistent with the client’s needs.
We explained to the client how to better use their device according to the seasons:
In winter
Excessive ventilation should be avoided when the outside air is very dry, while still maintaining sufficient air renewal to control humidity and odors.
In spring and autumn
The air exchanger can help maintain good air quality, especially when the house remains closed for long periods.
In summer
Depending on the outside humidity, it is important to avoid letting in too much unnecessary humid air. Properly adjusted ventilation helps reduce discomfort without overloading the air conditioning.
Airflow balancing
After the mechanical repairs, we performed an airflow check at the grilles. The goal was to ensure that stale air was properly extracted and that fresh air was well distributed. Proper balancing directly contributes to air quality, comfort, and the durability of the device.
An unbalanced air exchanger can cause effects that clients sometimes associate with other HVAC problems: overly dry home, condensation, persistent odors, poorly ventilated rooms, or general discomfort. That’s why we always consider the entire installation, not just the metal box suspended from the ceiling.
Final result: a quieter device and restored ventilation
At the end of the intervention, the Venmar air exchanger was operating with a much more stable airflow. The vibration noise had been reduced, the connections were better sealed, the filters and core had been cleaned, and the client received concrete recommendations to prevent the problem from returning quickly.
The result was:
- better air circulation;
- reduced unwanted noises;
- reduced air leaks around the device;
- better understanding of the settings by the client;
- more balanced ventilation;
- peace of mind for the coming months.
Common mistakes to avoid with an air exchanger
Several service calls for air exchangers in Laval, Montreal, Longueuil, on the North Shore and the South Shore come from avoidable problems. Here are the mistakes we regularly see in the field:
Never cleaning the filters
A dirty filter is one of the most common causes of performance loss. It can also give the impression that the motor is faulty, when the problem is simply an air restriction.
Forgetting the recovery core
The core is at the heart of the device’s operation. If it is clogged, heat recovery and airflow decrease.
Modifying ducts without professional inspection
Moving, crushing, or extending a duct can unbalance the entire system. Even a small modification can change the pressure and reduce efficiency.
Turning off the device for long periods
Some owners completely turn off their air exchanger to save energy, but this can harm indoor air quality, especially in newer or well-insulated homes.
Ignoring vibration noises
A slight noise can indicate a loose connection, a poorly positioned duct, or a part that is starting to wear out. The faster the intervention, the simpler the repair.
Why call on AirGreen for an air exchanger
An air exchanger is an integral part of the residential HVAC ecosystem. It influences comfort, humidity, odors, air quality, and sometimes even the performance of other systems like a central heat pump, an electric furnace, or an air conditioning system.
At AirGreen, we regularly work on residential installations in the greater Montreal area, in Laval, Longueuil, on the North Shore and the South Shore. Our approach is based on a complete diagnosis: device, ducts, controls, airflow, noise, humidity, and actual behavior in the home.
In this project in Laval-des-Rapides, the main issue was not to quickly replace the air exchanger, but to understand why a still functional device was no longer delivering the expected result. This precision allows proposing the right solution, at the right cost, without unnecessarily replacing components.
Regular maintenance to avoid emergency calls
A well-maintained Venmar air exchanger can provide excellent performance for many years. However, maintenance should not be left to chance. Depending on the environment, usage, and house configuration, it may be necessary to clean the filters several times a year and schedule a more comprehensive inspection periodically.
For homeowners in Laval-des-Rapides and surrounding areas, preventive maintenance can help avoid:
- airflow losses;
- persistent odors;
- excessive humidity;
- condensation;
- unusual noises;
- premature motor wear;
- more costly repairs.
An air exchanger is not always the most visible equipment in a home, but when it stops working properly, indoor comfort quickly deteriorates. This intervention demonstrated that a thorough diagnosis, complete cleaning, correction of connections, and adjustment of the airflow can transform the operation of a device without necessarily requiring a replacement.