Replacing a twenty-year-old air exchanger without demolishing the existing ductwork
A house on Île-Bizard–Sainte-Geneviève, approximately 3,200 sq. ft. across two floors plus a finished basement, built in the mid-1990s. The original air exchanger was still running. That is precisely what made the diagnosis difficult: the unit was making noise, so the owner assumed it was doing its job.
It had not done so for years.
Our visit was requested for an indirect reason: humidity levels rising above 55% every winter despite a basement dehumidifier, along with a persistent odor in the laundry room. Replacing the HRV was not part of the customer's plan. It became one after the measurements.
What we found on the original unit
A heat exchanger from the late 1990s, controlled by a mechanical dial humidistat—the kind of control that provides no information and that no one ever touches.
The findings, in order:
- Cracked heat-exchange core. A paper or polymer core eventually becomes deformed. When it cracks, outgoing stale air and incoming fresh air mix directly inside the unit. The system continues moving air—it no longer renews it.
- Measured exhaust airflow: 41 CFM, for a house that needed more than twice that amount. The fan had lost performance, and the filters had never been changed.
- Noisy bearings on the supply motor, causing the humming that the customer interpreted as a sign of proper operation.
- Corroded condensate pan, with seepage underneath the unit.
We put the measurements in writing before proposing anything. A customer who sees 41 CFM on paper does not need to be convinced.
Why we chose the Fantech HERO 250H-EC
EC motors change the logic of ventilation
The major difference between standard models and -EC versions of Fantech lies in their electronically commutated motors. In practical terms: instead of two or three fixed speeds, the unit continuously adjusts its airflow.
On the HERO 250H-EC, this provides a range of 31 to 252 cfm at 0.4 in. w.g. This ratio between minimum and maximum airflow—more than 1 to 8—is what allows a system to ventilate very gently and continuously, increasing output only when the house needs it.
The impact on energy consumption is direct: 34 W at the low end, 260 W at full speed, with a fan efficiency of 2.5 cfm per watt. By comparison, a conventional-motor model of similar capacity runs at around 0.8 to 1.3 cfm per watt. A house ventilated continuously twelve months a year feels this difference on its utility bill.
Performance data
- Airflow: 31 to 252 cfm at 0.4 in. w.g.
- Connections: round 6-inch ducts, top-mounted ports.
- Adjusted sensible efficiency : 85 %.
- Sensible recovery efficiency : 82% at 0 °C, 63% at -25 °C.
- Power supply: 120 V, maximum current 6.4 A.
- Dimensions: 24 7/8 in × 27 7/8 in × 15 3/8 in, 57 lb (26 kg).
- Certifications: cETL, HVI, ENERGY STAR.
A nuance we explain systematically because it goes against intuition: at -25 °C, the HERO 200H delivers 67% sensible efficiency versus 63% for the 250H-EC. The more expensive model is not the best in every category. The 250H-EC more than makes up for it in annual energy consumption and modulation range, but if recovery in very cold weather had been the only criterion, we would have recommended something else. We don't sell the option that benefits us.
Recirculation defrosting
The HERO uses recirculation defrosting: in very cold weather, the unit passes indoor air through the core to thaw it, rather than simply shutting off the supply fan.
The house never goes into negative pressure during these cycles. In a house this size in L'Île-Bizard–Sainte-Geneviève, exposed to winds from Lac des Deux Montagnes, this detail prevents the cold drafts felt on the upper floors in January. These models also include an interlocked mechanical backdraft damper that blocks outdoor air when the unit is off.
Working with an existing duct network: inspection first
A replacement is faster than a new installation only if the existing ductwork is in good condition. We never assume that it is.
What we checked
- Sealing the joints at all four connections and on accessible sections. Two detached aluminum-tape joints were redone.
- Exterior duct insulation. The insulation on the fresh-air duct had collapsed over approximately three feet in the service cavity. It was replaced.
- Condition of the interior flex ducts. A collapsed or punctured flex duct throws off the entire balance. Two sections were replaced with rigid ductwork.
- Exterior caps. The grilles were partially blocked by plant debris and a nest. They were cleaned, and one cap was replaced.
- Intake and exhaust vent placement. The two caps were correctly spaced to begin with—we kept them, avoiding two new holes in a brick cladding.
What we redid
- Complete suspension of the new unit with anti-vibration springs and flexible sleeves at all four connections.
- New condensate drain with a primed trap and verified slope.
- Dedicated electrical circuit sized for the EC model’s current.
- Complete balancing with a differential manometer, with the readings recorded in writing and left on the unit.
The work took a day and a half, compared with two and a half days for a complete installation from scratch. That is the real advantage of a replacement: the ductwork accounts for most of the labor time.
The ECO-Touch IAQ controller: what it really does
The hallway wall now has an ECO-Touch IAQ, Fantech’s touchscreen. Three points are worth understanding before paying for this type of control.
ECO mode and VOC detection
The unit detects total volatile organic compounds and indoor humidity. In ECO mode, the system adjusts its airflow based on what it actually measures in the home, rather than according to a fixed schedule.
This is where the EC motor really proves its worth. A modulating controller connected to a unit with two fixed speeds can only operate in an all-or-nothing manner. Paired with an EC motor, it allows fine adjustment. The controller and the unit must be selected together, not separately.
Manual controls
The display provides direct access to: SPEED to select a fixed speed, MAX to force full output — after a shower, during a gathering, or while painting. The VENT mode indicates that the unit is actively ventilating.
The indoor humidity reading, displayed continuously on the screen, is the most useful tool for the homeowner. It turns a vague feeling into a number. The target we recommend for a Quebec winter: 30 to 40%. Above 45% during severe cold, windows begin to condense.
The square of drywall to the right of the display
On this job, the old controller covered a larger area than the new one. We patched the drywall and left the repair ready for painting, since the client did not have the corridor's paint color available.
We mention it for a simple reason: it's the kind of detail that is never discussed in a quote and surprises the client at the end of the work. Replacing a controller almost always leaves a mark on the wall. We warn you in advance and prepare the surface rather than leaving a hole.
Repair or replace: how we decide
We do not recommend replacement as a reflex. Here is the framework we use:
- Cracked or deformed core → replacement. A damaged core defeats the unit's very purpose.
- Noisy motor on a unit over 15 years old → replacement. The part, when still available, often costs half as much as a new unit.
- Filters, caps, seals, drain → repair. These are common HVAC maintenance tasks, not reasons for replacement.
- Measured airflow below 60% of the original value, with no identifiable cause in the system → replacement.
- Unit under 10 years old with adequate airflow → we look elsewhere. Moisture problems often come from an improperly balanced system or a recirculating range hood, not the heat exchanger.
Maintenance essentials
- Filters: rinse or vacuum them every 3 to 6 months. MERV 8 and MERV 13 options are available for households with sensitivities.
- Core: remove it and wash it with warm, soapy water once a year. This habit, more than anything else, determines whether the unit lasts 12 or 22 years.
- Outdoor caps: inspect them in spring and fall. On the large wooded properties of L'Île-Bizard–Sainte-Geneviève, nests and leaves obstruct the grilles faster than they do in the city.
- ECO-Touch screen: monitor the humidity reading. A rise above 45% in winter signals a problem before it appears on the windows.
Regulatory framework and financial assistance
Balanced mechanical ventilation is governed by the Quebec Construction Code in new construction, and the Novoclimat program makes it a performance requirement. When replacing equipment, no specific additional obligation applies—but the installation must follow the same industry best practices regarding clearances, spacing between outdoor intakes, and condensate drainage.
Regarding financial assistance: active programs in Quebec primarily target the building envelope and heating systems. We verify each project's eligibility at the time of the work, based on the criteria in effect that day. This is the only way to avoid unpleasant surprises when applying.
Our service areas
AirGreen installs, replaces, and maintains air exchangers, heat pumps, wall-mounted air conditioners, and central systems in L'Île-Bizard–Sainte-Geneviève, Pierrefonds, Roxboro, Dollard-des-Ormeaux, Sainte-Anne-de-Bellevue, and throughout the island of Montréal, as well as in Laval, Longueuil, the North Shore, and the South Shore.
If your air exchanger is more than fifteen years old, makes noise, or you have never washed its core, an airflow measurement settles the question in twenty minutes. Write to us: we measure before making recommendations.