Bathroom Exhaust
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Bathroom Exhaust

fans . Reduce . energy use by 90% and cut through that thick shower fog. Philip Jones. Problem:. Failing bathroom exhaust fan – often stalls. Noisy. Built-in light missing its lens. Never happy with performance – post-shower condensation.

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Bathroom Exhaust

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Presentation on theme: "Bathroom Exhaust"— Presentation transcript:


Bathroom Exhaust fans Reduce energy use by 90% and cut through that thick shower fog

Philip Jones



Failing bathroom exhaust fan – often stallsNoisyBuilt-in light missing its lensNever happy with performance – post-shower condensationIssue of potential mold and insulation damage44W power draw for the trouble 



Fan exhausts into soffit / attic – very bad

Fan 50 cfm; should be at least 70

cfm for room size

Solution should minimize amount of conditioned (heated/cooled) air loss through exhaust fan while still fulfilling task of clearing humidity (as well as unwanted scents)

Should support 3 uses of bathroom: teeth brushing, etc.; toilet use; shower use

Search of replacement fans did not look any nicer, use much less energy or otherwise entice replacement

Panasonic ERV with heat transfer from exhaust to fresh supply – cool, but cfm too low; application wrong (continuous vs. intermittent use)

Panasonic ERV search led to best conventional replacement: Panasonic 24.5W

Even better, Panasonic had Green version: ECM motor at




WhisperGreenLED FV08VKSE3

80 cfm / <0.3 sones8W or less fan motorFan only works as hard as needed by duct work to meet constant cfm (energy efficiency junkie’s dream)Two modes – shower vs. settable simple air exchange – multiple operator control optionsBuilt-in LED 11.5W“Nightlight” 0.8W (same light dimmed)Can fully enclose fan with insulation



Aluminum roof vent with damperSmooth rigid-wall PVC (Al would be better) ducting with two 45° elbows (better than one 90°) – 7 ft overall run3 ft. straight section to first elbow with slight pitch away from fan (to reduce any condensate back into fan)Mastic-sealed jointsFoam board enclosed fiberglass insulation over fan, initial ductingFiberglass insulation over rest of ducting enclosed by 7” diameter flexible aluminum duct

Shown without insulation in place




Must support 3 functions in bathroom with minimal air exhaust to accomplish function

Must automatically turn itself off in all modes (see above)

Must be easy to use and useable without training

Motion sensors work great but what if just brushing teeth?

Moisture sensors work great, but what if just using toilet?


Timer switch to power fan

Toggle switch for low speed (toilet) or high speed (shower)

Upper switch for

light; lower switch for nightlight

Lower fan speed setting adjustment under fan grill



$395, including ductwork, electric (no labor cost)

$115 (40% ) net-premium for energy saving

Most of the labor is in getting the ducting right

Completely satisfying solution

Using 3 to 8W for fan