An HRV behind an access hatch: service access is is designed before the first duct
To Saint-Louis-de-Gonzague, the unit cannot be cannot be seen. It occupies a cavity built behind a partition wall finished basement, accessible through a opening made between two studs, closed off with a removable panel. The the visual result is clean: no no exposed enclosure in the room, no visible ductwork, no perceptible noise noticeable.
This type of integration has a drawback we often encounter a renovation setback: a unit recessed unit that no one can remove the core. A HRV invisible and inaccessible can no longer be maintained eighteen months. The entire design of this project therefore began with the reverse — the service opening first, the unit's location afterward, the ducts last.
The house and airflow calculation
The home includes three bedrooms, two bathrooms, bathroom, a kitchen open to the living room, a basement family room and a laundry room. According to the room-by-room method, room in the Building Code, the total ventilation capacity is is calculated by adding the airflow rates standardized:
- Primary bedroom : 10 L/s
- Each other bedroom : 5 L/s
- Living room, dining room, family room, kitchen : 5 L/s each
- Each bathroom and laundry room : 5 L/s
The total here is approximately 55 to 60 L/s, or approximately 115 to 130 cu. ft./min. A unit whose the maximum capacity coincides exactly with this figure would operate continuously at full speed — noisy, energy-intensive, and without no margin for boost mode after a shower or dinner.
This is the reasoning that led to V180H75RT : 199 ft³/min of maximum capacity, operating around 120 to 130 cu. ft./min under normal operation, with the necessary reserve for peaks.
The specifications of the V180H75RT
| Parameter | Value |
|---|---|
| Continuous airflow | 65 to 199 cu. ft./min at 0.2 in. w.g. |
| SRE at 0°C | 78 % (at 64 cfm) |
| SRE at −25°C | 68 % (at 83 cfm) |
| Apparent sensible efficiency at 0 °C | 82% (at 64 cfm) |
| Connections | 4 × 6-inch round, on top |
| Dimensions | 21.7 in H × 24.8 in W × 21 in P |
| Weight | 47 lb (21.3 kg) |
| Motors | PMSM ECM |
| Defrost | By recirculation |
| Filtration | MERV 8 |
| Approvals | ENERGY STAR®, HVI certified, cUL/UL |
| Warranty | Core 10 years |
The 68% SRE at −25 °C deserves is worth emphasizing: it is one of the better behavior in extreme cold of the residential range vänEE, and the difference of only ten points with the performance at 0°C indicates a core that does not collapse when the season becomes demanding.
The heater duct heater: the accessory that we we add here
On the duct of fresh-air intake, upstream of the unit, a electric duct heater has has been inserted. The metal housing with digital display visible on the side of the HRV is the control.
The vänEE range offers two models for this application :
- 02120 — 2,000 W, 220 V, 6-inch diameter, adjustable setpoint from 0 to 40°C.
- 1604103 (EDH 6.1) — 6-inch diameter, 1 kW, thermostat internal to a floor.
When this accessory is justified
We do not we do not install it by default. Three situations make it relevant:
- The fresh-air distribution discharges directly into living areas, without passing through the return of a central system that would temper the air. A 5°C draft in a living room feels it, and the owner responds by reducing the airflow—thereby canceling the ventilation.
- The house has a combustion appliance wants to avoid any reduction in and one intake airflow during defrost defrosting.
- The intake system is long or passes through a cold space, which lowers the delivered air temperature again.
To on the contrary, we we refuse to offer a heater as a corrective measure for an undersized, an improperly selected core or an uninsulated duct. In these cases, the accessory heats air to compensate for a design design, and the owner pays this electrical defect every winter.
What it actually consumes
A element of 2 kW correspond, in instantaneous power, to a bedroom electric baseboard heater. This a worrying figure alongside wrong: the heater operates only when the air temperature upstream drops below the setpoint, and its the thermostat switches it off as soon as it is reaches. During a heating season in Montérégie, its operating time actual operating time remains a fraction of the hours.
The setpoint is set low—around 2 to 5°C — and not to a comfortable temperature. A a heater set to 20°C turns into as a space heater permanent and makes the bill skyrocket without improving comfort, since the air then passes through the core heat-recovery core that already moderates it.
Duct geometry: the hidden cost of tight elbows the invisible cost of tight elbows
The the connection combines galvanized rigid duct, of gray insulated flexible hose and a black insulated flexible hose toward the outlet exterior. In a cavity of this dimension, changes in direction take place over short distances, which which produces tight curves.
This is the constraint we monitor most closely. more carefully because it cannot be seen does not appear in the final figures:
- A bend in a flexible duct whose radius is less than once the diameter can add as much pressure loss as than about ten feet of straight duct.
- The flexible hose crushed or pinched as it passes through a riser creates a permanent restriction that the unit will compensate by turning faster, longer longer, and harder.
- A duct flexible hose left too long and collapsed in an accordion multiplies the surface friction. internal friction.
Our rule for this type of cavity: pull the flexible hose taut, never soft, and make the changes of direction changes greater than 45 degrees in rigid elbow rather than a flexible-hose curve.
The access panel of access: the dimensions that make maintenance possible
For a air exchanger built-in remains serviceable, the opening must allow three movements :
- Open the cabinet door through its full travel.
- Extract the heat-recovery core horizontally, without bending it.
- Remove the two MERV 8 filters without the tear on the frame.
Specifically, this requires at least front clearance of at least the core depth, plus a few inches of clearance. We check this point on site, unit in hand, before closing the partition— not afterward.
Auto-balancing: what it measures and what it does not repair
The platform Virtuo Air Technology electronically measures the airflow of each fan and adjusts the motors ECM up to the balance between incoming air and the exhaust air. This saves time considerable and precision superior to manual balancing.
It one must nevertheless understand what this the function does not do. It equalize two airflows; it does not corrects not a restrictive network. If both circuits are poorly designed, the unit will balance one on the other—at a lower actual airflow at the target while consuming more. The display will show a consistent result, and the owner will have no way to know that their home is under-ventilated.
That is why we we systematically read the maximum airflow reached after the test and compare it with the calculated target. A a significant discrepancy points to the ducts, not to the unit.
The mistakes that we see most often with this type of installation
- Install the unit without a service hatch. The most costly mistake: it the core to become clogged until the failure.
- Set the duct heater to a comfortable temperature. Consumption Consumption multiplied, no comfort benefit.
- Run the airflow test before installing the exterior covers. The values the readings obtained then mean nothing.
- Use uninsulated flexible ducting on exterior runs. Condensation is guaranteed from the very first cold.
- Power the heater on a shared circuit. A A 2 kW element at 220 V requires its own properly sized circuit protected by an electrician.
- Do not record the settings. Airflow maximum, minimum airflow, mode, and heater setting should should appear on a label affixed nearby the hatch.
Maintenance of a unit recessed
Every 3 months — Filters MERV 8 remove them, clean them or replace them. On a unit behind a hatch, we recommend set a calendar reminder, since the unit does not remind itself visually to the homeowner.
Every fall — Core removed, vacuumed, rinsed with lukewarm water soapy water. Check the defrost damper and proper condensate drainage.
Every winter — Inspection of the duct heater : proper setpoint, clean element, no sign of overheating on the housing.
Twice a year — Inspection of exterior hoods, particularly in agricultural areas where plant debris obstructs the grilles.
Assistance programs financial
The installation of an air exchanger alone does not constitute generally not, in Quebec, a measure eligible for financial assistance stand-alone; provincial programs direct support toward the building envelope building and address ventilation as an air-quality requirement that accompanies this work. The criteria vary from one year to the next, and we verify them when preparing the quote rather than advancing a figure.
What the Beauharnois-Salaberry homeowners
A successful installation behind a partition finished installation rests on a precise sequence: calculate the required airflow before choose the unit, plan the opening of service before installing the cabinet, pull the ducts taut and limit the tight bends, then verify that the measured flow rate meets the calculated target.
The vänEE AI Series V180H75RT brought here the 199 ft³/min capacity, the 68% SRE at −25 °C, the ports 6-inch upper ones and the necessary self-balancing. The electric duct heater, set low, completes the system without the distort it.
At AirGreen, we we design and carry out theHVAC installation andHVAC maintenance air exchangers, of heat pumps and wall-mounted air conditioners to Montreal, Laval, Longueuil, on the North Shore, on the South Shore and in the municipalities of Beauharnois-Salaberry and Haut-Saint-Laurent. Each system starts again with its measured flow rates, recorded and explained.