Your house was built in the 1970s or 1980s. The walls have character, the floors creak a little, and you love your neighborhood in Ahuntsic or Rosemont.
But there's this little problem that comes up every winter: excessive condensation on the windows, a lingering musty smell, and the feeling that the air is never really fresh.
You have a heat recovery ventilator (HRV) that was installed a few years ago, but you've never really maintained it. You're not alone. Requests for cleaning of air exchangers increased by 18% in Montreal in 2025, mainly among owners of older homes who are finally realizing the importance of this maintenance.
The INSPQ estimates that approximately 35% of homes built before 1980 in Quebec have problems with excessive moisture. A poorly maintained air exchanger does not solve the problem—it makes it worse.
Why Maintaining an Air Exchanger Is Essential in Older Homes
Montreal’s old houses were built at a time when indoor air quality wasn’t yet a concern. Air flowed in and out naturally through cracks, poorly insulated windows, and doors that didn’t close tightly.
When you renovated and installed new windows, you made your home much more airtight. That’s great for your heating bills. But it creates a new problem: stale air gets trapped inside.
That’s where the air exchanger becomes crucial. It removes contaminated air and brings in fresh air, while recovering heat so you don’t waste money. But only if it’s clean and working properly.
Moisture and Mold: The Invisible Enemies of Old Houses
Old houses in Montreal often have basements made of fieldstone, foundations that let in a little moisture, and insulation that dates back to another era.
That moisture has to go somewhere. Without adequate mechanical ventilation, it condenses on cold surfaces, seeps into the walls, and creates the perfect environment for mold.
In 2025, the INSPQ released clear data: 35% of homes in Quebec built before 1980 show signs of excessive moisture or mold. In Montreal, with its long winters and humid summers, the problem is even more pronounced.
Mold isn't always visible. It hides behind furniture, in closets, and inside walls. But you breathe in its spores every day.
How a Poorly Cleaned VRC Can Contribute to Respiratory Problems
A clogged air exchanger becomes a breeding ground for health problems.
Dirty filters no longer trap particles. Dust, pollen, and mold spores circulate freely throughout your home instead of being filtered out.
A clogged heat exchange core reduces airflow. As a result, the relative humidity rises above 60%, creating ideal conditions for the proliferation of dust mites and mold.
The symptoms are insidious. You might think it’s just seasonal allergies, a lingering cold, or normal fatigue. But these respiratory problems get worse inside your home and improve when you go outside.
Children and the elderly are particularly vulnerable. Asthma worsens. Respiratory infections become more frequent. Sleep quality declines.
All of this can be prevented by regularly cleaning your air exchanger.
Myth or reality? «No need to clean every year»
That’s the most persistent myth you hear. «My VRC has been running for five years—why clean it now?»
Here are the facts versus the myths:
| Myth | Reality |
| A VRC doesn't get very dirty | Our data shows that 80% of homeowners neglect to maintain their filters for more than 6 months |
| In the winter, you don't need ventilation | Winter is actually the time when your VRC works the hardest and accumulates the most dirt |
| As long as it works, it's fine | A clogged VRC can operate at 40% of its efficiency without you even noticing it |
| Cleaning is too expensive | Neglecting maintenance can cost you an additional 25% in heating expenses and lead to premature replacement |
The RBQ and CAA-Québec recommend a thorough maintenance check of the filters every 3 to 6 months, and an annual professional cleaning of the entire system.
In an older Montreal home with a lot of construction dust, pets, or one located near a busy street, clean even more often.
Schedule a free inspection with our certified experts to assess the actual condition of your system before winter.
Steps for Cleaning an Air Exchanger in an Old House
Visit Cleaning an air exchanger It's not rocket science, but you have to do it right. Following a logical order prevents damage to the components and ensures a thorough cleaning.
According to our data at Vortex Air, approximately 80% of Montreal homeowners completely neglect filter maintenance for more than 6 months. Many don’t even know where their air exchanger is located.
Step 1 – Turn off the power and remove the filters
Safety first. Before touching anything, turn off the power to the air handler at the circuit breaker panel. Look for a circuit breaker labeled «HRV,» «air exchanger,» or «ventilation.».
Open the heat exchanger housing. On most residential models, there are latches on the sides that you simply need to unlock. The user manual (often affixed to the inside of the door) shows you how.
Remove the filters. There are usually two: one for the incoming air and one for the outgoing air. Note their orientation before removing them—they must be reinstalled in the same direction.
Check the condition of the filters in the light. If they are dark gray or black, if they smell musty, or if you see dirt buildup, they need to be cleaned or replaced.
For washable filters (most are), vacuum them first to remove dry dust. Then, wash them in lukewarm water with mild soap. Let them dry completely—at least 24 hours—before reinstalling them. Damp filters in the system promote mold growth.
If the filters are too dirty or damaged, replace them. They cost between 20$ and 40$ per pair, depending on the model. It’s a small investment that makes a huge difference in air quality.
How often should you do this? Check the filters every 3 months and clean them every 3 to 6 months, depending on their condition. In an older home with more dust, aim for every 3 months.
Step 2 – Clean the core and ducts
The heat exchange core is the heart of the system. This is where the heat from the outgoing air is transferred to the incoming air.
Remove the core according to the manufacturer's instructions. On most models, it simply slides out of its rails once the filters have been removed.
Examine it against the light. You'll probably see dust, cobwebs, and maybe even small pieces of debris stuck between the heat exchange plates.
For basic cleaning, gently vacuum between the panels. Use a soft brush to remove stubborn dirt without bending the thin metal or plastic panels.
For a deeper clean, some cores can be washed. Check the manual—not all of them are washable. If yours is, use a gentle stream of water (do not use a pressure washer, as it could damage the plates). Let it dry completely for at least 48 hours.
In older homes in Montreal where humidity is high, corrosion is often seen on metal components. A whitish film or brownish spots indicate oxidation. If the corrosion is severe, the core will need to be replaced.
The ducts leading to the air exchanger also accumulate dirt. Inspect them with a flashlight. If you see significant buildup, professional cleaning using specialized equipment (HEPA vacuum with 99.97% efficiency) is recommended.
Step 3 – Check the defrosting and airflow
During the Montreal winter, defrosting becomes critical. When cold air comes into contact with warm, humid air in the heat exchanger core, ice can form.
Modern air exchangers have an automatic defrost cycle. Check to make sure it is working properly by observing the system for a few hours on a cold day.
If excessive ice builds up or if the system fails to defrost, the problem may be caused by faulty sensors, poorly insulated ducts, or an imbalance in airflow.
Speaking of air flow, the Quebec Building Code, Section 6.3, specifies minimum fresh air flow rates for each room. For a standard residential home, the target is at least 35 liters per second (L/s) in total.
You probably don't have the equipment to measure this precisely, but you can do a simple test. Hold a tissue in front of the air vents. It should be drawn firmly against the grille. If it falls or barely stays in place, the airflow is insufficient.
Low airflow indicates clogged filters, a dirty air filter element, blocked ducts, or fans that are losing power.
Step 4 – Monitor Relative Humidity and CO₂
Indoor air quality isn't just about how clean the system is. Humidity and CO₂ levels indicate whether your air handler is actually doing its job.
The ideal relative humidity ranges from 40% to 50% in winter. Below 30%, the air becomes too dry and uncomfortable. Above 60%, you create conditions favorable to dust mites and mold.
A hygrometer costs between 15$ and 40$ at any hardware store. Place one in your bedroom and one in the living room to monitor the humidity levels.
If humidity levels remain consistently too high despite having a clean air exchanger, the problem may be due to insufficient airflow or a source of excessive moisture (a leak in the basement, drying laundry indoors, or too many plants).
CO₂ is another important indicator. In a well-ventilated home, levels should remain below 1,000 parts per million (ppm). Above 1,500 ppm, you may begin to experience fatigue, difficulty concentrating, and headaches.
Residential CO₂ sensors now cost between 80$ and 200$. It’s an investment that immediately shows you whether your ventilation is adequate.
Not sure if you can do it on your own? Schedule a home maintenance visit today—free estimate! Call Vortex Air at 514-214-7492.
Professional Cleaning vs. DIY: Which Should You Choose for Homes in Montreal?
The question we’re always asked: «Can I really do this myself, or should I hire a professional?»
The honest answer? It depends on how comfortable you are with maintenance tasks, the condition of your system, and the age of your home.
Basic maintenance—changing the filters, cleaning the core, and performing a visual inspection—is something you can definitely do yourself. It’s like changing the oil in your car: it can be done with just a few tools and a little know-how.
But for a deep clean—especially in an older home with years of buildup—hiring a professional offers significant benefits.
The Benefits of Professional Cleaning
A certified technician arrives with equipment you don’t have at home. The professional HEPA vacuum captures 99.97% of particles as small as 0.3 microns. Your home vacuum cleaner? It might capture 85% of them and release the rest back into the air.
According to data from CAA-Québec published in 2025, a professional inspection uncovers approximately 70% hidden defects that the average homeowner would never notice. Electrical wires that are starting to deteriorate, leaky seals, and motors showing signs of premature wear.
We also inspect the ducts using specialized cameras. In older homes, we sometimes find sections of ductwork that are disconnected, crushed by past renovations, or filled with construction debris dating back decades.
Professional cleaning includes tests that you cannot perform yourself. Precise measurement of airflow rates in each room. Analysis of combustion gases if there is a heat exchanger connected to a furnace. Checking the airtightness of the ducts using pressure tests.
The system is also calibrated after cleaning to ensure that it operates at maximum efficiency. Airflow rates are adjusted, defrost cycles are checked, and automatic controls are tested.
At the end, you’ll receive a comprehensive report with before-and-after photos, detailed measurements, and recommendations for future maintenance. If you sell your home, this report serves as proof that you’ve properly maintained the systems.
The Limitations of Homemade Cleaning
DIY cleaning has its limits, especially in old Montreal homes.
You may damage delicate components without realizing it. The plates in the heat exchanger core bend easily. The seals can tear if you apply too much force. Electrical connections can come loose.
In an older home, systems sometimes have unique installation features that only an experienced eye can spot. We’ve seen «creative» DIY fixes made over the years that work but don’t comply with building codes and can cause problems.
Corrosion is particularly insidious in Montreal’s old, damp homes. You may be cleaning your system thoroughly without realizing that some metal components are so corroded that they’ll fail in a few months.
The biggest risk? Reinstalling the system incorrectly after cleaning it. Filters installed upside down, a core that’s out of place, ducts reconnected the wrong way—it happens more often than you’d think.
Cost Comparison: Professional Cleaning vs. DIY
A DIY cleaning job costs between 50$ and 100$ if you need to buy cleaning supplies, replace filters, and perhaps a new hygrometer. How much time will it take? Allow 2 to 4 hours for an initial thorough cleaning.
Professional cleaning in Montreal generally costs between 400$ and 700$, depending on the complexity of the system and its initial condition. This includes the comprehensive inspection, Cleaning with HEPA equipment, adjustments, and a detailed report.
Several companies, including Vortex Air, offer discounts ranging from 10% to 20% for new customers or for annual maintenance contracts.
The return on investment is tangible. A clean, properly calibrated system reduces your energy consumption by 15% to 25%. On an annual heating bill of 2,000$, that represents savings of 300$ to 500$. Professional cleaning pays for itself in 12 to 18 months.
Not to mention that you’ll extend the life of your system by 3 to 5 years. Replacing an air exchanger costs between 2,500$ and 4,500$, including installation. Preventive maintenance delays this major expense.
Get a clear, no-obligation quote and save up to 20% on your first visit with Vortex Air.
Grants and Assistance Programs to Upgrade or Clean Your VRC
Improving the ventilation in your older home doesn't have to drain your savings account. There are several assistance programs available to Montreal homeowners.
The rules change regularly, but here is what was available in early 2025.
Rénoclimat and J’erénoveco: Programs You Should Know About
Rénoclimat It remains the flagship program for energy-efficient renovations in Quebec. It operates in two stages: an assessment before the work begins and an assessment after the work is completed.
The assessor identifies all possible improvements, including ventilation. If you replace an old system with a modern, efficient air exchanger, you can receive between 500$ and 1,500$ in financial assistance.
The bonus? When you combine the installation of a VRC with other improvements such as insulation or a heat pump, The subsidies add up. Some homeowners receive more than 10,000$ in total.
According to our findings, approximately 25% of owners of older homes in Montreal used Rénoclimat to upgrade their ventilation systems between 2023 and 2025.
I'm renovating, recently launched by the Quebec government, offers additional assistance to low-income households. If you are eligible, up to 80% of the costs of certain renovations may be covered.
The Program Heat Green, which provided assistance for replacing oil-fired systems, ended in the summer of 2025. But keep an eye out—new programs are announced regularly.
Eligibility Requirements and Procedures
To qualify for Rénoclimat, your home must be located in Quebec and be your primary residence. Condos and multi-unit dwellings with up to four units are eligible.
The work must be performed by a contractor who holds the appropriate RBQ licenses. Keep all your invoices—you’ll need them for the final assessment.
The entire process typically takes 3 to 6 months from the initial evaluation to receiving your grant check. Please plan accordingly.
The good news? Starting in 2025, everything will be done online through the Quebec government’s platforms. No more complicated paper forms. You create a file, upload your documents, and track its progress in real time.
For Montreal, Laval, Longueuil, and other cities in the metropolitan area, also check to see if your municipality offers additional local programs. Some offer tax credits for energy-efficient renovations.
Find out about your grants with a Vortex Air advisor. We offer a free assessment and help you navigate the available assistance programs. Call us at 514-214-7492.
Practical Tips for Maintaining Air Quality After Cleaning
Cleaning your air exchanger is an excellent first step. But improving indoor air quality is a marathon, not a sprint.
Here's how to maintain your results and breathe clean air all year round in your old Montreal home.
When and How to Replace the Filters
Filters are your first line of defense against indoor air pollution. They capture dust, pollen, and mold spores before they circulate throughout your home.
Set a reminder on your phone: check the filters on the first day of each season. That’s four times a year—spring, summer, fall, and winter. It takes 5 minutes each time.
If the filters are dirty, clean or replace them. Never let them go beyond 6 months, even if they seem fine.
For families with allergies or asthma, consider HEPA filters, which capture 99.97% of particles. They cost a little more (40$ to 80$ per pair), but the difference in air quality is remarkable. Our customers report a 40% to 60% reduction in allergy symptoms after switching to HEPA filters.
In an older Montreal home, you generate more dust than in a new home. Old wooden floors, plaster that’s slowly crumbling behind the walls, and aging insulation—all of these things release fine particles into the air.
Using Smart Sensors to Monitor Indoor Air Quality
You can't improve what you don't measure. Indoor air quality (IAQ) sensors provide you with objective data on what you're breathing.
Modern sensors measure several parameters: temperature, relative humidity, CO₂, fine particulate matter (PM2.5), and sometimes volatile organic compounds (VOCs).
The adoption of these sensors increased by 25% in Montreal condos and homes in 2025. Prices have dropped significantly—you can now find decent models for between 100$ and 250$.
Place one sensor in your bedroom and one in the main living area. Check the data regularly. You’ll quickly learn which activities affect air quality: cooking without a range hood, cleaning that stirs up dust, or keeping windows closed for too long.
Some sensors connect to your phone and send you alerts when levels become a cause for concern. They remind you to increase ventilation, open a window, or check to see if your air exchanger is working properly.
Check the exterior air intakes before winter
The air exchanger has two ducts that lead outside your home: a fresh air intake and a exhaust air outlet.
These openings must remain clear at all times. But in Montreal, various things can block them as the seasons change.
In the fall, fallen leaves pile up. If your air intake is near the ground or in a corner, it can become completely clogged after just a few days of wind.
In winter, snow and ice become your enemies. After a major storm, go check to make sure the openings aren't buried. We've seen systems completely blocked by snowdrifts pushed by snowplows.
Frost also forms around the exhaust vent when warm, humid air comes into contact with extreme cold. A little frost is normal, but if it completely blocks the opening, gently brush it away.
In the spring, birds sometimes build their nests near hot-air vents. Make sure no nests are blocking the vents.
Install protective screens if you haven't already. They prevent debris, small animals, and insects from entering the ducts. They cost between 15$ and 40$ and can be installed in 10 minutes.
Get our free seasonal maintenance guide – The Vortex Air Guide for a moisture-free winter in 2025! Visit vortexair.ca or call 514-214-7492.
Why Choose Vortex Air Ventilation in Montreal
Montreal’s old houses deserve experts who understand their unique characteristics. You don’t treat a 1975 plex in Ahuntsic the same way you would a new condo in Griffintown.
At Vortex Air, we've built our reputation on our knowledge of Montreal buildings and our people-oriented, transparent approach.
Our methodology: inspection, cleaning, follow-up
Our process follows the INVC protocol, adapted to the realities of older homes.
Comprehensive inspection: We always start with a visual and technical inspection. How old is the system? How was it installed? Are there any signs of corrosion or previous repairs? We measure airflow rates, check the relative humidity, and inspect accessible ducts.
Professional Cleaning: We use HEPA-certified equipment that captures 99.97% of particles. The filter core is cleaned or replaced depending on its condition. The ducts are vacuumed using negative pressure, which prevents dust from spreading throughout the house. All electrical components are inspected.
Detailed report with photos: You’ll receive a comprehensive report in French with before-and-after photos of each step. We record precise measurements of airflow, humidity, and CO₂ levels. We identify any potential issues and explain our recommendations in plain language.
Personalized advice: We don’t just give you a generic list of tips found online. We’ll discuss the specifics of your home. «Your outdoor air intake is too close to the ground; it’s going to get clogged every winter.» «Your ducts were probably installed before current standards were in place; here’s what we can do.»
Follow-up: Three months after our visit, we'll call you to check in and see how things are going. Have you noticed any improvement? Do you have any questions? We're here for the long haul.
Testimonials from Montreal Homeowners
Diane, the owner of a 1978 home in Rosemont, called us after years of moisture problems: «I had mold that kept coming back in the same spot near my bedroom window. Three companies came out before Vortex Air. The others just cleaned the visible mold. Vortex Air inspected my air exchanger and discovered that it was operating at barely 30% of its capacity. Since the thorough cleaning, I haven’t had any problems. It’s been 18 months now.»
Marc, a duplex manager in Ahuntsic: «Mohamed from Vortex Air came over one Saturday morning for an emergency. My upstairs tenant was complaining about strange odors. He found that the HRV was completely clogged and that moisture was building up in the ducts. He cleaned everything that same day and explained exactly how to prevent the problem in the future. Fast, honest service at a very reasonable price.»
Sophie, who recently bought a house built in 1982 in Brossard: «I bought my first house last November. I didn’t know anything about air exchangers. The team at Vortex Air patiently explained everything to me without making me feel clueless. They cleaned the system, which clearly hadn’t been maintained in years. They even showed me how to check the filters myself. I recommend them to all my friends.»
Over 500 customers have placed their trust in us over the years. You don't grow like this without doing things right.
Schedule your consultation with a local expert. Breathe easier starting this week—call us toll-free at 514-214-7492.
FAQ – Everything You Need to Know About Air Exchanger Cleaning in Montreal
How often should you clean an air exchanger?
Filters should be checked every 3 months and cleaned or replaced every 3 to 6 months, depending on their condition. The heat exchanger core and the entire system should be professionally cleaned once a year. In an older home with more dust or if you have pets, aim for every 3 months for the filters and twice a year for professional cleaning.
What products should I use for an older VRC?
Use only lukewarm water and mild soap to clean the filters and the core. Avoid harsh chemicals, bleach, or abrasive cleaners, which can damage delicate components. For systems that are heavily soiled or have mold, consult a professional who will use products certified as safe.
Does cleaning prevent mold?
Yes, absolutely. A clean, properly functioning air exchanger controls relative humidity by removing humid air and circulating fresh air. This keeps humidity between 40% and 50%, a level at which mold cannot grow. But if you already have visible mold, you’ll need to treat it separately before addressing the ventilation issue.
How much does professional cleaning cost in Montreal?
A complete professional cleaning service—including an inspection, HEPA cleaning, adjustments, and a detailed report—typically costs between 400$ and 700$ in Montreal. The price varies depending on the complexity of the system, its initial condition, and the accessibility of the ducts. Several companies, including Vortex Air, offer discounts ranging from 10% to 20% for new customers.
What are some common mistakes to avoid?
The most common mistakes: reinstalling the filters the wrong way, putting the wet filter back into the system (which promotes mold growth), using harsh chemicals that damage components, using excessive force when removing the core and bending the delicate plates, and forgetting to turn off the power before starting. Always follow the manufacturer’s manual.
My heat exchanger is too old: should I replace it?
It depends on its condition and age. A well-maintained heat recovery ventilator (HRV) can last 15 to 20 years. If yours is more than 15 years old, shows signs of significant corrosion, or requires costly repairs, replacing it becomes a good option. Newer models are much more efficient (heat recovery up to 90% vs. 65–70% for older models). A professional inspection will give you the facts you need to make the right decision.
Does cleaning really improve air quality?
Yes, in measurable terms. Our customers report an average reduction of 40% to 60% in allergy symptoms after a thorough cleaning. Air quality sensors show clear improvements: fine particulate matter (PM2.5) reduced from 30% to 50%, CO₂ levels maintained below 1,000 ppm instead of exceeding 1,500 ppm, and humidity stabilized within the ideal range. It’s a direct investment in your family’s health.
Can I clean my HRV in the winter, or should I wait until spring?
You can clean your HRV any time of year, but fall (September–October) is ideal because it prepares the system for the months of heavy use ahead. If you didn’t clean it in the fall, don’t put it off until spring—winter is precisely when your HRV works the hardest and when indoor air quality is most important. A professional can clean your system in the winter without any problems.
Breathe Easier in Your Old Montreal Home
Your home has character and history, and you love it. But it also deserves fresh, healthy air.
A clean, well-maintained air exchanger makes all the difference between living comfortably and having to put up with humidity, odors, and respiratory problems.
You now know how to maintain your system on your own, when to call in a professional, and how to make the most of available grants.
Call Ventilation Vortex Air at 514-214-7492 or visit vortexair.ca To schedule your free inspection and professional cleaning.
We serve the entire Greater Montreal area: Ahuntsic, Rosemont, Plateau-Mont-Royal, Saint-Laurent, Laval, Brossard, Longueuil, and the surrounding areas. Service is available 7 days a week, from 7 a.m. to 9 p.m.
Our INVC-certified (and soon-to-be NADCA-certified) technicians know Montreal’s older homes like the back of their hands. We speak to you in French, clearly explain what we’re doing, and never push services you don’t need.
More than 500 Montreal families have already placed their trust in us. Join them and finally breathe the fresh air you deserve in your home.
