Ventilating a home without ductwork: LaSalle’s typical puzzle
A home in LaSalle’s Highlands area, built in 1968. Electric baseboards in every room, no ductwork, no furnace. The basement was finished in 2021, the insulation redone, and the windows replaced. Since then, the homeowner had been describing a phenomenon she could not put a name to: “It smells like a closed-up house, even when I open the windows.”
We handle this type of call constantly. An electrically heated home without ductwork has no mechanical means of replacing its air. As long as the building envelope was leaky, air renewed itself—poorly, but it renewed itself. After a thorough renovation, that accidental mechanism disappears.
Installing an air exchanger in a home without ductwork is not the same operation as in a home with a furnace. There is no return-air duct into which to inject fresh air, and no central blower to distribute it. The entire duct network has to be created.
What we measured before proposing anything
Our technical assessment lasted an hour and fifteen minutes. The readings:
- Relative humidity: 61% one February morning, with persistent condensation along the bottom of the north-facing windows.
- CO₂ in the primary bedroom: over 1,400 ppm after a night with the doors closed. Above 1,000 ppm, sleep quality and concentration measurably deteriorate.
- Existing exhaust: a bathroom fan on a mechanical timer and a recirculating range hood—so it vents nothing outside the house.
- Available mechanical space: a utility closet in the basement, shared with the water heater. Usable depth: 24 inches.
That final figure determined the choice of unit just as much as the airflow rates.
Why a Fantech ATMO 200H and not something else
The physical constraint comes first
The ATMO 200H from Fantech is an HRV (heat recovery ventilator) with side connections — side-port. All four ducts exit from the sides, two on the left and two on the right, rather than from the top.
In a closet with a low ceiling and a water heater below, this configuration changes everything. A unit with top ports would have required at least 12 to 16 inches of clearance above the cabinet for the elbows — space this house did not have. The side ports allowed us to suspend the unit tight against the ceiling and run the ducts horizontally.
Choosing the model often begins with the room’s geometry, not the performance specifications. This is a reflex many installers get backward, and it ultimately results in a unit that is inaccessible for maintenance.
Performance data
- Airflow range: 60 to 200 cu. ft./min at 0.4 in. w.g.
- Connections: four 6-inch round ducts.
- Sensible recovery efficiency : 75% at 0 °C, 60% at -25 °C.
- Adjusted sensible efficiency : 81 %.
- Fan efficiency: 1.3 cu. ft./min per watt — the best in the ATMO HRV range.
- Power consumption: 50 W at low speed, 168 W at high speed. Maximum current 1.4 A on a 120 V circuit.
- Dimensions: 21 7/16 in. high × 23 7/8 in. wide × 16 5/8 in. deep, weighing 46 lb (21 kg).
- Certifications: cETL, HVI, and ENERGY STAR.
The HVI certification deserves a closer look. It is the organization that tests airflow rates and efficiencies according to a standardized protocol. A non-HVI-certified unit advertises figures that no one has verified. When a customer compares two quotes, this is the first filter to apply.
Defrosting by stopping the fan: let’s talk about it frankly
The ATMO 200H uses defrosting by stopping the supply fan. When the core risks freezing in very cold weather, the unit temporarily shuts off the outdoor air intake and lets indoor air warm the heat exchanger.
It is a simple, robust system with very few parts that can fail. Its limitation is well known: during these cycles, the house briefly experiences slight negative pressure.
In this installation, that was not a problem—the system is entirely dedicated, the house is modest in size, and the cycles remain short. We would have recommended a model with recirculation defrost in two specific cases: a very airtight house with a combustion appliance, or integration with the return air of a central air-handling unit. We tell the client before signing, not afterward.
The job: two days, a system built from scratch
The suspension
The unit is suspended from the closet ceiling by four chains fitted with vibration-isolating springs, fastened to a wooden support added beneath the joists. The springs are not a luxury: an HRV transmits low-frequency vibrations through the structure, and a 1960s house with a finished basement amplifies them remarkably well. A rigid suspension can be heard in the bedroom above.
We also left the necessary clearance in front to open the unit's door and remove the core and filters without dismantling a single duct.
The ducts and their identification
The system uses insulated flexible ducts with an exterior vapor barrier. Each section was hand-labeled as soon as it was installed: Fresh from outside, Exhaust, and so on.
This labeling may seem trivial. It is not. In five years, when a technician—ours or someone else's—opens this closet, they will immediately know which duct goes where. Without identification, the first thing that happens during troubleshooting is a connection mix-up: fresh air goes outside, stale air comes back into the house, and no one understands why the windows are streaming with condensation.
The two ducts connected to the outside are insulated along their entire length, without exception. An uninsulated outdoor-air duct passing through a heated space develops condensation, drips, stains the ceiling, and eventually leads to an insurance claim.
Distribution in a house without ductwork
The selected system is entirely dedicated:
- Extraction from the upstairs bathroom, basement shower room, and a point near the kitchen.
- Fresh air supply to the living room, primary bedroom, and second bedroom.
This principle is the foundation of balanced ventilation: we remove air where moisture and odors are produced, and introduce fresh air where people live and sleep. The supply grilles have been positioned high up, away from beds and seating areas, to prevent any draft sensation in January.
The outdoor vents
Two louvered wall caps, more than 6 feet apart, positioned away from the dryer vent and parking area. We also check their height relative to the accumulated snow level: in LaSalle, as throughout the island of Montreal, a cap that is too low ends up buried after the first serious snowfall.
Balancing and the reference chart
The unit has a balancing chart printed by the manufacturer on its door: it relates the pressure measured at the unit's ports to the actual airflow in cfm. We use it with a differential pressure gauge to adjust the dampers until the supply and exhaust differ by less than 10%.
The final readings are written on the unit with a marker and provided to the customer in writing. An unbalanced air exchanger consumes electricity continuously without delivering what it was purchased to do—and there is no visible way to detect it.
The electrical connection and condensate drain
Power supplied by a dedicated outlet installed behind the unit, with the cord neatly secured. Condensate drain connected with a primed trap to the existing floor drain, with a continuous slope. We check this slope with a straightedge, not by eye.
The mistakes we repair for others, month after month
Our service calls for air exchangers installed by third parties in Montreal, Laval, Longueuil, on the North Shore and the South Shore all look the same:
- Crushed or overly long flexible ducts. Each tight bend adds pressure loss. A poorly stretched flexible-duct system can reduce actual airflow by 30 to 40% without triggering a single warning light.
- No insulation on the outdoor ducts. Condensation is guaranteed, along with ceiling stains during the first two winters.
- Outdoor vents too close together. The unit draws back in the air it has just exhausted.
- Rigid mounting. The unit becomes noisy, and the client turns it off.
- No balancing report. No proof that the system is doing what it should.
- No explanation to the client. The costliest mistake: a unit that is turned off benefits no one.
Maintenance: what the homeowner can do herself
- Filters: vacuum or rinse every 3 to 6 months. An upgrade to MERV 8 or MERV 13 is available for households with allergies.
- Heat-exchange core: remove it and wash it with warm, soapy water once a year.
- Exterior grilles: clear away lint, leaves, and snow at each change of season.
- Speed: run continuously at low speed. This is the mode designed for the home. Turning the unit off in winter “to save money” brings you right back to the original problem.
Codes, Novoclimat, and financial assistance
In new construction in Quebec, balanced mechanical ventilation is governed by the Building Code, and the Novoclimat program imposes requirements that make the HRV essential. In renovations, the direct obligation is weaker, but the physical principle remains the same: the tighter the building envelope, the less tolerable the absence of an air exchanger.
For financial assistance, the programs currently in effect mainly target insulation, air sealing, and heating systems. We validate eligibility on a case-by-case basis, according to the programs active when the work is carried out, rather than announcing an amount that might not materialize.
Where we work
AirGreen installs and services air exchangers, heat pumps, wall-mounted air conditioners, and central systems in LaSalle, Verdun, Ville-Émard, Lachine, Saint-Henri, Côte-Saint-Paul, and throughout the island of Montréal, as well as in Laval, Longueuil, on the North Shore, and on the South Shore.
If your home is heated with electric baseboards, has been renovated without adding ventilation, or your windows run with condensation every winter despite a dehumidifier, write to us. We measure before proposing, and we leave the figures in writing.