As houses have been built tighter, the air inside stops changing on its own. Heat recovery ventilation (HRV) and energy recovery ventilation (ERV) both solve that without throwing away the energy in the air being exhausted. This guide covers how each works, where they differ, and how to pick between them.
What is heat recovery ventilation?
An HRV exchanges indoor and outdoor air continuously while recovering heat from the outgoing stream. Fresh air comes in, stale air goes out, and most of the heat stays in the building.
How heat recovery ventilation works
The unit is a core, two fans, filters and ductwork. The core transfers heat between the incoming and outgoing streams, which never mix. The fans move the air; the filters keep dust and pollen out of the core and the house.
Sensible recovery efficiency generally falls between 60% and 90% depending on the unit and the airflow it is running at. At 20 °C indoors and −5 °C outdoors, a unit recovering 80% delivers incoming air at roughly 16 °C instead of −5 °C, so the heating plant has far less to do.
What to look at on an HRV
- Recovery efficiency — always quoted at a specific airflow. The same core reads higher at low airflow and lower at high airflow.
- Filtration — standard filters capture dust, pollen and coarse particles. Higher-MERV filters add resistance, which costs airflow.
- Humidity control — some units include a dehumidistat that raises ventilation when indoor humidity climbs.
- Sound — residential units typically run in the 30–48 dB(A) range. Check the figure at the speed the unit will actually run at, not at its lowest.
What is energy recovery ventilation?
An ERV does everything an HRV does and also moves part of the moisture between the two air streams. In winter it keeps some indoor humidity in the building rather than exhausting it; in summer it keeps some of the outdoor humidity out.
HRV or ERV: the difference that decides it
| Feature | ERV | HRV |
|---|---|---|
| Heat recovery | Yes | Yes |
| Moisture transfer | Partial, through the core | None |
| Summer latent load | Reduced | Not reduced |
| Winter indoor humidity | Retains some moisture indoors | Dries the house further |
| Condensate drain | Often not required | Normally required |
| Best suited to | Humid and mixed climates; very airtight cold-climate houses that run dry in winter | Cold climates where the house tends to run humid |
The drain row is the one that shows up on site. An ERV that needs no condensate connection removes a drain run, a trap and a freeze risk from every unit — which matters most when the same unit is repeated across a whole building.
What else to weigh up
- Climate and how the house behaves. The old rule that cold means HRV has softened. Very airtight houses often run too dry in winter, and the moisture an ERV returns is useful there.
- Airflow at real duct resistance. Size from the airflow the unit delivers at the project's external static pressure, not from a catalogue maximum.
- Space and service access. Cabinet size, duct port direction and the room needed to pull filters and the core vary between models.
- Controls. Decide early whether the project needs a bathroom boost timer, a thermostat input or an interlock with the furnace or fan-coil blower.
The EXINDA ERV range
Five residential models, each with its own listing in the HVI Certified Products Directory. Net supply is the HVI certified value at 0.4 in. w.g.; SRE is the HVI rated value at 0 °C, measured at the airflow shown beside it. All five are certified to UL 1812 for safety and CSA C439 for performance under CSA certificate 80227354, and all five are listed with no condensate pipe connection.
| Model | Installation | Net supply at 0.4 in. w.g. | SRE (at airflow) | HVI ID |
|---|---|---|---|---|
| ICMBCNF1AYE | Ceiling, 4 in. | 95 CFM | 77% at 66 CFM | 2005353 |
| ICMBCOFF1AYE | Ceiling, 6 in. side ports | 136 CFM | 74% at 64 CFM | 2005359 |
| ICMBCOFF1AYS | Ceiling, 6 in. side ports | 170 CFM | 86% at 42 CFM | 2005500 |
| IWMBCOOF1AYE | Wall, 4 in. top ports | 102 CFM | 72% at 66 CFM | 2005360 |
| IWMBCOFF1AYE | Wall, 6 in. top ports | 153 CFM | 77% at 57 CFM | 2005356 |
For an apartment or a smaller home on a 120 V supply the usual choice is the Breeze 54–100 CFM wall-mounted ERV, whose technical brief covers the checks to make before ordering. Compare the whole range for larger homes and multifamily suites.
Frequently asked questions
Are HRV and ERV systems suitable for all buildings?
Both are used in houses, apartments and commercial buildings. Size, occupancy and climate decide which fits, not building type alone.
Do they reduce energy costs?
Yes, by recovering energy from air that would otherwise be exhausted. How much depends on the recovery efficiency at the airflow the unit actually runs at.
Do they need regular maintenance?
Yes. Clean or replace filters on schedule, inspect the core, and check fans and motors. Filter neglect shows up as lost airflow before anything else.
Does an ERV need a condensate drain?
Not always. All five EXINDA Breeze models are listed with no condensate pipe connection; an HRV normally needs one. Confirm against the model submittal.
Can they be integrated with the heating system?
Yes. A dry contact can request the furnace or fan-coil blower so ventilation air is distributed even when the thermostat is not calling — see how the ERV interlock starts the HVAC blower.
Getting a model checked against your design
Send the building type and location, the required airflow in CFM, the design external static pressure in in. w.g. and where the unit will be mounted. EXINDA returns a model recommendation with the airflow at that operating point, the submittal, the dimensional drawing, a copy of CSA certificate 80227354 and lead time.
