help - bathroom fan problem

19 years ago

hi all.

I am in a condo building and am remodeling my bathroom. Currently the bath fan has a 3" duct and I want to replace the fan. However, most of the current models are for a 4" duct. I installed a Panasonic Whisper fan for a 4" duct and needless to say it is louder than a whisper. Do I need to take it out and get a fan made for a 3" duct or is there a way to make it work? It would not be easy to replace the duct.

any input would be greatly appreciated.

thank

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Comments (4)

hounds
19 years ago
What size CFM fan did you install? I am not sure that the noise level is solely related to your duct size. I just installed a Panasonic 110 CFM fan as well and was surprised at the higher than expected noise level. After reading many positive posts, it was somewhat dissappointing (I did not expect it to be super silent either). I'm sure it is a quality product though. I did call Panasonic (waste of time)and the vendor (Wave Plumbing - great folks) who has offered to replace the fan but did say that the 110 CFM fans are indeed much noisier.
woodinvirginia
19 years ago
My observation has been than 99% of you by the expensive whisper lite fans and then you go to Home cheapo & get a full run of flex duct for it.
THAT WILL NOT WORK WITH THIS FAN.

This fan is about as high end as you can get, most contractors won't read the directions cause they are used to installing the el cheapo models.

If you READ THE INSTRUCTIONS & use Galvanized straight pipe or even straight aluminum pipe and you block the pipe as the directions say on a downward angle towards a soffit or an eave or a gable vent. 99% of you wan't hear a ding dong thing afterwards when you turn it on.

Also if you intend to use a attic duct with this fan the duct run must extend straight for at least 3 feet before using a preferred 60 degree angle to the attic vent Not a 90 degree angled vent.
One more thing this fan needs to have an INSULATED duct when running through unconditioned attics..
Otherwise the condensation will form and may be the start of something ugly...mold & mildew...

Here is a link that might be useful: Panasonic Instructions
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johnmari
19 years ago
"My observation has been than 99% of you by the expensive whisper lite fans and then you go to Home cheapo & get a full run of flex duct for it.
THAT WILL NOT WORK WITH THIS FAN."

Not so fast. I have "the expensive WhisperLite" fan and flex duct, and I am extremely happy with the quietness of our fan. I can barely hear it unless I am standing directly underneath it (it is less than 7 feet from the shower floor to the bottom of the fan cover) and listening. I had to pick my battles with the electrician and GC by that point, so I called Panasonic tech support and they said not to worry about it, there would not be a real difference in the noise level. They were 100% right. So if you can't replace the duct it is not the end of the world.

Anyway, to answer the OP's question, the Panasonic WhisperFit has a 3" duct adapter and comes in both lighted and non-lighted versions. Both have a 1.0 sone rating at 80cfm, 1.5 sones at 110cfm. That's one heck of a lot quieter than most - I did a few minutes' worth of research and found that most 3" duct fans are up around 4 and even as high as 6 sones! Call Panasonic fan tech support at 1-866-292-7292 and ask if using the duct reducer would appreciably increase the noise level.

Hounds, Panasonic says very clearly on their website that the standard 80cfm fan is 0.3 sones and the 110 is 0.8 sones. Doubling the number of sones doubles the loudness level, so of course the 110cfm fan is louder than the 80cfm.
fotostat
19 years ago
Panasonic's instructions mentioned installing a short piece of flex duct. Did anyone do that? How did you do it, just clamp the flex around the galv. straight duct?