Accurate Tests for Exhaust Fans, HRVs & ERVs

General Requirements for Bathroom & Kitchen Exhaust Fans

Code baseline: Per ASHRAE 62.2 and ENERGY STAR, bathroom fans must provide ≥ 50 CFM (intermittent) or ≥ 20 CFM (continuous); kitchen fans typically require ≥ 100 CFM.
Fans must exhaust directly outdoors, not into attics or interstitial spaces. Dampers and proper duct sealing are essential for compliance and moisture control.

With the Retrotec PP105 Powered Flow Hood attachment, your DucTester becomes a portable powered flow hood.
Simply mount the hood to the DucTester and place over the grille to measure airflow in CFM—ideal for spot testing exhaust fans.
Quick setup ensures minimal equipment and makes testing fast in the field.

The FlowFinder MK2 is a dedicated powered flow hood featuring zero-compensation down to 0.01 Pa, far beyond standard passive hoods.
It maintains ±3% accuracy even under low pressure and in tight spaces, while passive hoods can produce huge errors (20–50%).
It measures exhaust, return, and supply flows from 6–326 CFM (up to 500 CFM in compensated mode), with fast response, WiFi updates, and 12-hour battery life.

The TEC Exhaust Fan Flow Meter pairs with Retrotec DM‑32 gauge to deliver precise airflow readings from exhaust fans.
Select “Exhaust Flow Meter” mode on the DM‑32, then connect control and pressure tubing to the fan flow meter for instantaneous CFM/Pa feedback.

DC-motor fans (common in modern exhaust devices) often underperform due to higher duct resistance and static pressure—traditional flow hoods may misread them.
Flow hoods like the FlowFinder MK2 or powered hoods like DucTester hood overcome this by compensating airflow and measuring directly at the grille.
For ERVs and HRVs, use return or supply balancing hoods with sensitive zeroing capability to handle flow under very low pressure drops.
Extremely tight installations, small grilles, or low airflow rates are best handled by FlowFinder or similar tools.

Tool/Method	Best For	Accuracy/Range	Notes
DucTester + Flow Hood	Basic fan airflow checks	~±5–10% CFM	Low cost, easy setup
FlowFinder MK2 Otto Hood	Kitchen, bath, ERV, HRV and tight spaces	±3% accuracy, 6–500 CFM range	Gold standard for airflow
DM‑32 + TEC Exhaust Flow Meter	Quick plug-and-play gauge readings	Depends on gauge calibration	Integrated solution with gauge