1. Did Panasonic Make a Contractor-Proof Bath Fan?
Ben Hannas --
Jonathan Coulter --
Bruce Manclark --
Data, Not Dogma - July 18-19, Goldendale, WA
Measuring Air Flow, Energy Use, and Static Pressure in a Variety of As-Installed Conditions

2. The Test Setup

3. Panasonic Whisper Green Fan Controls
Dial-in CFM
Timer not visible to homeowner

4. Metering

5. Variables Duct type (metal flex, sheet metal)
Elbow placement (immediate, 2-3’)
Flap (open, screwed shut)
Termination (forced passive, duct roof vent)
Grille (with, without)
Installation type (perfect, small oops, they probably won’t catch this mistake)

6. Baseline and Ideal Baseline Ideal No duct, open flap, with grille
136 CFM, 1.5 Pa, 10 Watt
Ideal
2 feet straight before elbow, 5 feet up to roof duct vent termination
143 CFM, 45 Pa, 19.8 Watt

7. Duct Type No change between metal flex and sheet metal in ideal setup
141 CFM, Pa, 15 Watt

8. Changing the Termination
Passive attic vent used as duct termination
Shove it in and seal it
142 CFM, 22.2 Pa, 14.8 Watt
Duct roof vent
Meets code
143 CFM, 45.0 Pa, 19.8 Watt
As a note, running fan 24/7 at this rate is <$20/year

9. Real-world Duct Run We have a ladder and a phantom truss in the way!
CFM increased slightly (5 CFM)
Static pressure doubled to 46 Pa
Energy increased slightly, up to 21 Watt

10. Damper
With the same realistically awkward duct run, now tape the damper shut (but that never happens in real life)
CFM dropped almost in half, but still pulled 87 CFM
Static pressure jumped from 46 Pa to 128 Pa
Watts increased slightly, from 21 to 23 Watts

11. Calibrated Crush The “small oops” scenario
Damper open, but complex duct run
No change in CFM
Static increases from 46 Pa to 60 Pa
Watts increase from 21 to 24

12. Maybe They Won’t Notice

13. Maybe They Won’t Notice
Still pulled 57 CFM
140 Pa
Only 20 Watt