Ventilating a 5 ½ heated with electric baseboards: when there is no duct to connect to
Most articles about air exchangers start from an implicit assumption: the house already has a duct system. You connect the unit to the furnace return, adjust it, and you’re done.
In Mercier–Hochelaga-Maisonneuve, that assumption falls apart half the time. The neighborhood’s triplexes and duplexes, built between 1920 and 1960, are overwhelmingly heated with electric baseboards. No furnace, no plenum, no distribution network. Nothing to connect to.
This was exactly the situation in the apartment discussed here: a second-floor 5 ½ apartment in a triplex in the Hochelaga area, converted into a divided co-ownership property about twelve years ago, heated entirely by electric baseboards, with an electric water heater housed in a utility closet in the hallway. The closet’s floor space was already completely occupied.
We installed a FANTECH FIT 120E, an ERV—energy recovery ventilator—suspended by chains from the ceiling of the closet, above the water heater, with a fully dedicated duct system. Here is the complete reasoning, with the numbers to back it up.
The starting point: two winters of condensation and a painting bill
The owners contacted us in February. Their description was precise and typical of an airtight home without mechanical ventilation.
- Heavy condensation on the windows of the rear bedroom, enough to warp the wooden frame and stain the wall beneath the sill.
- Persistent cooking odors lasting twelve to eighteen hours after dinner, in a walk-through apartment where the kitchen opens directly onto the living room.
- Stuffy air in the morning in both bedrooms, with the doors closed.
- A bathroom fan that has already been replaced twice, with no measurable improvement.
This last point is revealing. A well-sealed home equipped only with exhaust fans operates under negative pressure: air is removed without supplying any. Replacement air then enters through air leaks — the window frame, the baseboard, the electrical conduit, the floor joint with the unit below. It is uncontrolled, uncomfortable, and does not improve indoor air quality.
Our hygrometer reading confirmed 61% relative humidity on a morning at –14 °C, whereas a target of 30 to 35% would be appropriate in these conditions. At this level, water vapour condenses on every cold surface in the home.
ERV or HRV: The Choice That Shaped the Entire Project
This is the most important decision in this project, and the one most often made blindly.
The Real Difference Between the Two Types
An HRV (heat recovery ventilator) transfers sensible heat between outgoing and incoming air. The moisture, meanwhile, leaves with the stale air and does not return.
An ERV (energy recovery ventilator) transfers heat and some of the water vapour. Its membrane core allows moisture to migrate in both directions according to the gradient.
In practical terms, for a Montréal home:
- In winter, the ERV returns some of the indoor humidity instead of expelling it all. In a small, well-sealed home ventilated continuously, this prevents a shift from excess humidity to excessive dryness — the notorious 18% relative humidity in February that makes floors crack and irritates the respiratory tract.
- In summer, it slows the entry of outdoor humidity. The FIT 120E has a total recovery efficiency of 64% at 35 °C, which means that a significant portion of the latent load on humid July days is intercepted before reaching the home. In a 5½-room apartment air-conditioned by a wall-mounted heat pump, this directly reduces the unit’s dehumidification workload.
When We Do Not Recommend an ERV
We prefer to say this clearly because the opposite is sold far too often:
- If the home has a structural excess of humidity — infiltration, a damp basement, drying laundry indoors, overcrowding — an HRV is the best choice because the goal is to exhaust the vapour, not retain it.
- If the unit is to be integrated into a central forced-air system, the HERO models with recirculation defrost are recommended by the manufacturer because they are equipped with an interlocked mechanical backdraft damper.
- If there is a naturally drafted combustion appliance in the unit, the defrost strategy must be examined in detail before making any choice.
In this case, none of these conditions applied. The unit is entirely electric — baseboard heaters, stove, water heater — so there was no risk of combustion-gas backdrafting. Excess humidity came from normal occupancy and the complete absence of ventilation, not from an unintended source. The HRV was the right tool.
FANTECH FIT 120E specifications
| Specification | Value |
|---|---|
| Airflow range | 40 to 127 CFM at 0.4 in. w.c. |
| Duct connections | 5 in., round, side |
| Power supply | 120 V / 1 phase, maximum current 1.4 A |
| Power consumption | 55 W (low) / 104 W (high) |
| Adjusted sensible recovery efficiency at 0 °C | 81 % |
| ERV at 0 °C | 74 % |
| ERV at –25 °C | 61 % |
| Total recovery efficiency at 35 °C | 64 % |
| Defrost | Supply fan shutdown |
| Dimensions | 23 5/32 in. H × 24 5/8 in. W × 10 in. D |
| Weight | 34 lb (15 kg) |
| Filtration | MERV 8 or MERV 13 optional |
Two figures deserve attention for this type of project.
The 10-inch depth. This is what makes the unit installable in a corridor utility closet. A 15-inch-deep cabinet simply would not have fit with the required clearances.
The 34 lb. weight. A unit suspended from the ceiling of a condominium must be properly supported, and a lightweight cabinet greatly simplifies anchoring — we will return to this below.
Installation in a 26-inch-wide closet
Suspending it from chains above the water heater
The utility closet had no available floor space: the electric water heater occupied it entirely. The only option was ceiling suspension.
We anchored the unit with four chains secured to the joists, not to drywall or furring strips. Each anchor point was located and verified before drilling. Between the chains and the cabinet, vibration isolators prevent structural noise from traveling to the adjacent bedroom — in a multi-unit building, vibration transmitted to a joist also travels to the unit below, quickly becoming a source of tension between neighbors.
Three clearances were maintained simultaneously:
- In front of the access door, to remove the filters and core without taking anything apart.
- Above the water heater, to allow its future replacement without disconnecting the heat exchanger. A water heater lasts ten to fifteen years; the ventilation unit lasts longer. Designing the installation while overlooking this detail guarantees a difficult job a decade from now.
- Around the side connections, to avoid tight elbows at the soffit outlet.
Standard or mirror: an ordering detail that changes the routing
The FIT series is available in two configurations: the standard version, with the fresh-air intake on the right, and the mirror version (suffix -D), with it on the left.
This is not a cosmetic detail. In a narrow closet, choosing the wrong orientation forces the two exterior ducts to cross above the unit, adding elbows, increasing pressure loss, and complicating insulation. We confirmed the exterior wall location—the rear façade of the triplex, facing the alley—before placing the order, and selected the configuration that sent both exterior ducts directly to the correct side.
On a rushed replacement job, this check is often skipped. It takes thirty seconds and prevents two permanent elbows.
The fully dedicated network
Without a central system, the only viable option is a fully dedicated network: ducts dedicated to the heat exchanger, extracting stale air where it deteriorates and delivering fresh air where the occupants spend time.
Exhaust points:
- Bathroom
- Kitchen, around the perimeter of the cooking area—never above the cooktop, where grease would destroy the core
- Washer-dryer closet
Supply points:
- Primary bedroom
- Second bedroom
- Living room
The routing was carried out in the suspended ceiling of the corridor and in a decorative soffit that we built along the kitchen wall, finished and painted to blend into the room. In a finished home, routing the ducts is often the main constraint, more so than the unit itself. We therefore plan the routing before confirming the model, not the other way around.
The drain above a water heater
An ERV produces less condensate than an HRV, since some of the moisture is transferred rather than condensed. It still produces condensate, however, and the drain here was routed to the washing machine drain, with a properly primed loop trap and continuous slope along the entire run.
We also installed a drain pan beneath the appliance. The rule is simple: when a water-producing appliance is suspended above equipment, a finished floor, or a neighbor’s living space, a second line of defense is required. The cost is marginal; the cost of water damage in a plex is not.
How we balance a FIT 120E: reading the label, number by number
The label affixed to the appliance door is not decorative. It is the balancing tool, and it is almost always ignored.
What this appliance’s label says
It shows a diagram with two measurement points—A for fresh-air supply, B for stale-air exhaust—and a lookup table correlating measured pressure with actual airflow.
| Target airflow (CFM) | Pressure at point A — fresh air (in. w.g.) | Pressure at point B — stale air (in. w.g.) |
|---|---|---|
| 120 | 0,75 | 0,56 |
| 110 | 0,82 | 0,62 |
| 100 | 0,89 | 0,69 |
| 90 | 0,96 | 0,76 |
| 80 | 1,03 | 0,82 |
| 70 | 1,10 | 0,89 |
| 60 | 1,17 | 0,96 |
| 50 | 1,24 | 1,03 |
The logic is reversed, which confuses those seeing it for the first time: the lower the pressure reading, the higher the airflow. A reading of 1.24 in. w.g. at point A does not indicate high airflow—it indicates 50 CFM.
The two rules listed on the label—and too many people ignore them
First rule: balance at Normal (high) speed. The label states this explicitly. Balancing at reduced speed produces unstable readings and an adjustment that does not hold when the appliance ramps up.
Second rule: never balance outside the indicated range. Here, the usable range runs from 50 CFM at the low end to 120 CFM at the high end. Trying to extract 140 CFM from an appliance whose label caps the flow at 120 falls outside the range in which the measurements are valid.
For this dwelling, we aimed for 100 CFM supply and 100 CFM exhaust, corresponding to target readings of 0.89 in. w.g. at point A and 0.69 in. w.g. at point B. The dampers were adjusted until these values were achieved, then the final readings were recorded and left on site with the appliance documentation.
A difference of more than 10% between supply and exhaust means a dwelling is permanently overpressurized or depressurized. In a plex, this pressure imbalance affects neighboring units through the stairwell and service penetrations. This is not a theoretical detail.
The mistakes we most often correct in the plexes of eastern Montreal
- Do not balance it at all. The unit operates, the client hears noise, and everyone assumes it has been adjusted.
- Hang the unit from drywall or furring strips rather than from the joists. Detachment is only a matter of time.
- Omit the drip tray beneath a unit suspended above equipment or finished flooring.
- Draw fresh air from the alley, at parking-lot level, or near waste containers. The orientation of the exterior hood deserves as much attention as the choice of unit.
- Install an ERV in a dwelling with a genuine excess-moisture problem. Vapor transfer then works against the objective.
- Connect the kitchen exhaust above the cooking surface. The core becomes irreversibly fouled.
- Run the unit only when it smells bad. Balanced ventilation is a continuous operating mode, not a corrective intervention.
Maintenance in a dense urban environment
Mercier–Hochelaga-Maisonneuve is crossed by major truck routes — Notre-Dame Street East, l'Assomption Boulevard, and Highway 25. The particle load is higher there than in an outlying residential neighborhood, making filter selection relevant.
- Every 3 months — inspection and replacement of the filters. We recommend MERV 8 as the standard and MERV 13 for occupants sensitive to fine particles, taking the additional pressure drop into account during balancing.
- Every 6 months — cleaning the membrane core according to the manufacturer's method. An ERV core is not maintained like an HRV core: it must not be rinsed in the same way, and improper handling compromises its moisture-transfer capacity.
- Annually — inspection of the exterior hoods, trap, drip tray, and revalidation of the balancing readings at points A and B.
Compliance, co-ownership, and programs
For new homes subject to the Quebec Construction Code, balanced mechanical ventilation is required, and it is a condition of the Novoclimat program. In an existing home like this one, adding an ERV is generally not directly subsidized — energy-efficiency renovation programs primarily target insulation, air sealing and heat pumps. However, as soon as the envelope of an older building is tightened, mechanical ventilation is no longer technically optional.
One condominium-specific point deserves attention: drilling through the rear façade for the exterior hoods generally affects a common area. We systematically ask the client to confirm the process with the condominium association before the work begins. A technically flawless installation carried out without authorization becomes a dispute, and we have no interest in putting a client in that position.
For your project in HoMa or elsewhere in Greater Montreal
At AirGreen, we treat homes without a central duct network as a full-fledged design project, rather than as a simplified version of a single-family home installation. This involves surveying the home, choosing between an HRV and an ERV based on the actual humidity profile, planning the ductwork layout before ordering the unit, anchoring the suspension to the structure, carrying out measured and documented balancing, and then providing occupants with a complete demonstration of how the system operates.
We carry out HVAC installations — air exchangers, wall-mounted and central heat pumps, air conditioners, heating systems — in Mercier–Hochelaga-Maisonneuve and throughout Montreal, Laval, Longueuil, the North Shore and the South Shore. Licence RBQ # 5645-9605-01.
For an assessment of your ventilation needs or a quote for a FANTECH air exchanger, contact us at (514) 316-2973 or sales@airgreen.ca.