Upgrading Bathroom Exhaust Fan with 3 inch ducts (2023 Update)

[Steven]

Hi, I am looking to upgrade the cheap builder installed exhaust fans in my bathrooms. They are incredibly loud. I can find lots of nice quiet ones, but they all required 4 inch (or greater) ducts. The only 3 inch duct vents I can find are...cheap and loud.

Does anyone know of a decent fan that will work with 3 inch ducts?

Thanks Steven

[Joseph Meehan]

One reason they are quieter is because of the larger ducts. That and they generally also move more air.

[Remi]

I think you can get an adaptor that will connect the 4" to the 3". It will make the fan a little louder than it should be, but if you buy a good quality quiet fan it will be a lot quieter than the cheap one you have now. Have you checked out the Panasonice "Whisper" fans? They're the wuietest (and most energy efficient) on the market. They're expensive, but good. Good luck.

[Mark]

bath exhaust fans are a bad idea anyway for a home...

in the winter they draw heated moist air outside,,,,instead... after your shower, just open the inside door and keep that warm moist air in your house..

in the summer, open a window...

if your using central AC in the summer, you are still better off closing the AC vent in the bath and opening the window...

Mark

[Bob]

May be he is trying to remove the smell instead of moist warm air.

[Joseph Meehan]

For the home as a whole, your comment makes some sense. However since that warm moist air stuck in the smallest room in the house means mold and mildew, they do make sense. Even your examples do not apply at all likely combinations of conditions.

[jim]

[Al Bundy]

"Remi" wrote in news:ZMwWg.113956$5R2.885@pd7urf3no:

Yea I picked up an hard plastic adapter for a buck or two at the Borg.

When I got the fan, I noticed they had a noise rating on the boxes or display.

[Al Bundy]

"Mark" wrote in news: [e-mail]:

Not sure I can buy into that one.

While higher humidity can make it feel warmer, that moisture in a tightly insulated house can raise hell in various ways. In cold climates it can contribute quite a bit to icing windows.

[buffalobill]

for quietest installation the fan goes in the attic and the intake feeds to it from the bathroom. see:Bathroom Exhaust Fans:

"A sone is a measure of loudness. The higher the sone rating the louder the sound. Understanding how loud an exhaust fan will be can be difficult, largely because bathroom exhaust fans are measured in sones, while most common noise levels we are familiar with are measured in decibels. Scientifically, one sone equals 40 phons, which is the loudness of a

1,000 hertz tone at 0 decibels above our threshold hearing level. The relationship between phons and decibels is not one-to-one (affected by, for instance, frequency), but for our purposes we will assume that decibels are roughly equivalent to phons. The chart below compares the sound level of a sampling of exhaust fans with the sound level of a number of other common sounds. Sone

0.3 Panasonic 60 cfm FV05VQ2 Fan

0.5 30 Phons 0.5 Rustling Leaves 1.0 40 Phons 1.0 A Quiet Refrigerator 1.5 Panasonic 100 cfm FV11VQ2 Fan 2.0 50 Phons 2.0 Quiet Home 3.0 Panasonic 380 cfm FV40VQ3 Fan 3.0 Normal Office 4.0 60 Phons 4.0 Nornal Television Volume Note that two sones are twice as loud as one sone, three sones are twice as loud as two sones, four sones are twice as loud as three sones, and so on."

Steven wrote:

[mcfriendly]

The Panasonic Whisper fans are outstanding!

Check out

some excellent information and prices (under Heating and Ventilation)

They also sell the duct adaptors for 4" to 3"

[Roger V.]

I also have the same question as the original poster, Steven. No one here addressed his question. Specifically, Does anyone know of a decent fan that will work with 3 inch ducts? Thank you.

[Smelly Bob]

So you advocate diffusing turd smell throughout the house?

[Skystew]

reducer is not what you want. The flow of air will be compromised trying to squeeze from 4” to 3”

[Skystew]

I have the same issue..My bathroom according to CFM measurements & fixtures suggests 200 cfm fan..builder put in 50cfm fan..and 3” duct. What i want to know is what is the largest fan (based on cfm) that can accommodate a 3” duct

[skystew92]

the author and others like myself have 3" duct; taking a 4" equipped bath fan and adding a 3" adapter compromises the efficiency of the fan...if it were the opposite going from 3" to 4" then that would work. We are just trying to find out who has the largest cfm available that comes with a 3" discharge

[Dean Hoffman]

Consumer Reports has two rated as Smart Buys. Kaze Appliance SNP100 BV Ultra Quiet 90 CFM, 0.8 Sone Bathroom Ventilation Exhaust Fan Both are 4" discharge though.

[Ed P]

You may have to find a fan that was made in the 1950s or so. Never saw one that was not 4" in many years. Check into upgrading the size of the vent hose and enjoy better ventilation.

[trader_4]

And what's the big deal if using 3" degrades the performance somewhat? A 4" fan going to 3" might still move more air than a 3" fan going to a 3" duct. It also depends on how long, how many turns, etc. If the 3" is short, one turn, etc it could outperform a long 4" with more turns. If the duct is easily accessible, I would replace it. Otherwise put in whatever fans are available. I would stay at lower CFM though.