What Are ERVs and HRVs?
HRVs (Heat Recovery Ventilators) transfer sensible heat between exhaust and incoming air.
ERVs (Energy Recovery Ventilators) transfer both sensible and latent heat (humidity) to improve indoor air quality and reduce energy waste.
Balanced systems avoid pressurization or depressurization of the building, improving IAQ and building durability.
How to Commission a New HRV
Design and installation must be coordinated as part of a complete building system:
Installation Setup:
Consume outdoor intake and exhaust terminations spaced at least ~10 ft apart.
Ensure filters, core, and condensate drain are accessible.
System Balancing:
Adjust dampers or grilles to match supply and exhaust CFM using a flow hood or magnehelic gauge setup.
Bureau guidelines (e.g. Lifebreath, Venmar) recommend equal intake/exhaust or slight positive supply.
Flow Verification at Registers:
- Use a flow hood (e.g. CPS EasyHood, Testo hot-wire anemometer) to verify per-room ventilation.
Tools & Protocols Best for HRV/ERV Testing
Recommended equipment includes:
Flow hoods capable of ±1 CFM to accurately measure low flow rates.
- Retrotec FlowBox / CPS EasyHood systems in combination with hot-wire anemometers for precise airflow measurements.
- DM‑32 gauge and DucTester with powered hood attachments for total system flow or balanced operation assessment.
Add to that, protocol guides like the California CEC HRV/ERV Verification Form outline how to verify system performance in multifamily or commercial buildings.
Tackling Field Challenges
On-site obstacles may include tight access, noisy spaces, or distorted flow readings:
Use mini capture hoods or modified grill masks for difficult-to-reach grilles.
Confirm that intake and exhaust paths are unobstructed—airflow distortions affect balance.
Account for environmental conditions like wind or duct leakage that may skew airflow results.
Some practitioners use basic flow hood systems or portable instrumentation to adapt testing setups when ideal conditions are not available.
Summary Table
| Topic | Key Takeaways |
|---|---|
| ERV vs HRV | ERVs transfer heat and moisture; HRVs only heat |
| Commissioning Process | Install, balance supply & exhaust, verify register flows |
| Best Tools & Protocols | Flow hoods, DM‑32/DucTester, official AHJ acceptance form |
| Field Obstacle Solutions | Use adapted hoods, verify pressure separation, mitigate distortions |
