Installation of a Venmar AVS EKO 1.5 Air Exchanger in Saint-Constant

45%, 52%, 19°C: what your air exchanger's screen is trying to tell you

The photo from this Saint-Constant project does not show the unit. It shows its wall control, and that is far more revealing. The screen displays four pieces of information, and together they tell the complete story of a poorly adjusted home: DEHUMIDISTAT mode, outdoor temperature 19°C, indoor relative humidity 52%, threshold set to 45%, and the message “limit exceeded.”

In plain English: the unit is ventilating at high speed because the house is more humid than the programmed threshold. That's exactly what it's supposed to do. The problem is that this 45% threshold was set once, during commissioning, and has never been changed since—and a single threshold cannot be right all year round in Quebec.

We installed a Venmar AVS EKO 1.5 here, controlled by the programmable Altitude wall control. This article is about both the settings and the unit, because in nine out of ten homes, it is the settings—not the equipment—that explains the discomfort.

The screen, decoded line by line

• Mode: DEHUMIDISTAT. The unit doesn't operate on a fixed schedule, but according to a humidity threshold. As long as indoor humidity remains below the setpoint, it runs at minimum ventilation. As soon as it exceeds it, the unit switches to high speed until the humidity drops back below the threshold.
• 19°C outdoors. The Altitude control displays the outdoor temperature. This isn't decorative: it is the data that should determine the humidity setpoint.
• 52% / set to 45%. The measured humidity is seven percentage points above the setpoint. The unit compensates.
• The arrow to the right of the setpoint. This is the button used to change the threshold. It takes three seconds. Most homeowners don't know it exists.

The 45% threshold: appropriate in September, costly in January

A fixed humidity threshold is a physical contradiction. The amount of water vapor indoor air can hold without condensing depends directly on the temperature of the home's cold surfaces—that is, the windows, and therefore the weather outside.

At 19°C outside, 45% indoor humidity causes no problem: the panes are warm, and nothing condenses. At -20°C, the same home at 45% sees its windows streaming with condensation, water accumulating in the PVC joints, and mold appearing at the bottom of the frames within a few weeks. The unit, meanwhile, considers everything fine: it is below its threshold.

The table we leave with the customer

Here are the setpoints we write on the commissioning sheet and recommend adjusting as the season progresses:

These are not theoretical comfort values. They are the thresholds beyond which a double-glazed window typical of a Saint-Constant home begins to condense.

The window is the home's best hygrometer

We always give the same checking instruction because it costs nothing and is more reliable than any sensor: in the morning, before opening the curtains, look at the bottom of the windows on the north side.

• No condensation: the setpoint is correct, or could even be raised slightly.
• Condensation that disappears within an hour: the setpoint is borderline. Acceptable.
• Persistent condensation or water running down: the setpoint is at least 5 points too high. Lower it immediately, not in the spring.

Air that is too dry is not desirable either—an irritated throat, wood movement, and static electricity. But between a home at 25% in February and a home whose window frames are rotting, the choice is not difficult.

The opposite trap: the dehumidistat in summer

This is exactly the situation shown in the photo: 19°C outside, 52% indoors, unit running at high speed.

An HRV transfers heat, not moisture. In July and August, when the outdoor air on the South Shore is humid, ventilating more intensely amounts to bringing in moisture while the house is trying to get rid of it. The dehumidistat, left active year-round, then starts working against the comfort it is meant to protect.

Our recommendation for a home in Saint-Constant, Delson, or Sainte-Catherine:

• Cold season: dehumidistat mode active, setpoint adjusted according to the table above.
• Warm season: dehumidistat disabled or setpoint raised to 55–60%, ventilation in continuous or intermittent mode, and dehumidification handled by a dehumidifier or the heat pump in the appropriate mode.
• In-between season: the best time of year. Cool, dry outdoor air, continuous ventilation at a sustained airflow rate, and no significant energy cost.

The Altitude control is designed specifically for these changes: it is programmable, includes a SMART mode that automatically adjusts operation, and displays all parameters on its LCD screen. It is compatible with the EKO, Solo, Duo, HE, Constructo 1.0, and Kubix lines.

The unit: EKO 1.5, ECM motors and 83% apparent efficiency

For this house, the choice of unit came down to two criteria: power consumption and low-speed performance—the two parameters that really matter for a machine that operates twelve months a year.

ECM motors: where the savings are

The electronically commutated motors in the EKO line offer an average 67% electricity savings compared with standard PSC motors. On a unit that runs continuously, the difference is not insignificant: 24 W in continuous operation is less than a light bulb.

This is also what makes humidistat control genuinely worthwhile. With a PSC motor, switching to high speed is costly; you hesitate to let the unit respond. With an ECM, modulation is smooth and the energy penalty remains low, allowing you to let the control do its job without watching the power bill.

83% SRE: what the figure means and what it does not mean

An apparent sensible efficiency of 83% at 0°C, at low speed, places the EKO 1.5 among the highest-performing residential units in its category. Two honest qualifications:

• This value is measured at low speed. At full airflow, it is lower—which is another argument for continuous low-speed operation rather than short high-speed cycles.
• SRE says nothing about humidity. An ERV removes humidity; it does not recover it.

The drain is not optional on the ERV version

At Venmar, the EKO line does not require a drain in most climate zones—but only in its HRV version. The ERV version, the one installed here, produces condensate during the cold season and must be connected to a drain. We regularly see units installed without a drain because the installer read the note too quickly. The result appears during the first February thaw, as a ceiling stain.

HRV or ERV: a decision that can still be made later

One feature of the EKO line is worth knowing: the unit is convertible from a heat recovery ventilator (HRV) to an energy recovery ventilator (ERV) simply by replacing the core.

In practical terms, if after two summers the homeowner finds that summer humidity is still the main irritant, they do not have to replace the unit: the core can be changed. We mention this systematically in our quotes because it is a rare fallback option in the HVAC field, where most poor choices must be paid for in full.

For a home in Saint-Constant, where winters regularly drop below -20 °C, the HRV remains our default recommendation: removing winter humidity is the dominant concern.

The project

• Top connections. The EKO 1.5 is a unit with connections on top, which means allowing for sufficient clearance above the cabinet. We systematically reserve the necessary space for the first few feet of straight ductwork: a tight elbow immediately at the outlet of a nozzle cancels out part of the performance we paid for.
• Decoupled suspension. The cabinet is suspended with decoupling at the anchors so that vibrations are not transmitted to the floor above.
• Washable core filters. No replacement cartridge to buy; just rinse them every two to three months.
• Exterior outlets. Set of IN2000 (1607100) caps, two 6-inch double-collar caps, with the required separation between the intake and exhaust, away from the dryer outlet and plumbing vents. We confirm the layout with the authority having jurisdiction: requirements differ from one municipality to another on the South Shore as well as the North Shore.
• Interior grilles. 5- and 6-inch Whisper registers, whose geometry limits whistling at high airflow rates.

Balancing: the measurement that gives meaning to everything else

Any discussion about humidity settings is meaningless if the airflow rates are not measured. We balance the system with a Magnehelic gauge connected to the pressure taps, using flow meters matched to the nozzle diameters, and then record the values on the form provided to the customer.

The manufacturer summarizes the issue in three points:

• Negative pressure: the house draws in unconditioned air through its leaks — higher energy costs, risk of mold, and the possibility of backdrafting combustion products from an appliance connected to a chimney.
• Positive pressure: warm, humid air is pushed into the walls and insulation, where it condenses.
• Balanced pressure: supply equals exhaust. This is the only acceptable state, and it requires a measurement, not an estimate.

Grants: the amount, and the condition that catches people out

The Rénoclimat program provides $500 for the installation or replacement of a heat recovery ventilation system. Two requirements apply.

The unit must be listed in section 3 of the Home Ventilating Institute (HVI) certified product directory. Venmar has been an HVI member since 1991, and its AVS units are HVI- and cUL-certified.

Above all, eligibility depends on the improvement in the EnerGuide rating between the pre-retrofit evaluation and the post-retrofit evaluation. Adding an HRV alone to an existing home increases energy consumption: without energy-efficiency measures carried out as part of the same project, the rating may deteriorate and the assistance may be refused, including for ventilation. The correct sequence is therefore: pre-retrofit evaluation, then HVAC installation combined with insulation or air sealing, followed by a post-retrofit evaluation. We confirm this point with the program adviser before including it in a quote.

What we ask the homeowner to do, and nothing more

1. Adjust the humidity setting four times a year, following the chart. Hold the wall control for three seconds at each change of season.
2. Look at the north-facing windows in the morning once a week in winter.
3. Rinse the washable filters every two to three months.
4. Clean the core once a year.
5. Check the outdoor caps in the spring.

At AirGreen, we install, replace, balance, and adjust residential ventilation systems in Saint-Constant, Longueuil, throughout the South Shore, as well as in Montréal, Laval, and the North Shore. If your heat recovery ventilator has been in place for years and no one has ever adjusted its humidity setting, there is a good chance that a tune-up visit will solve more problems than a new unit.