Wife purchased three of the quiet Broan QT080L bathroom exhaust fans with
light and night light. I tested it out on the kitchen table and it was quiet
so then I proceeded with the installation in the downstairs 1/2 bathroom.
The bathroom is down to studs and subfloor with all insulation removed for
remodel. The Broan has a 4" duct connection but the house has 3". Once
everything was connected, the fan wasn't all that quiet. The noise was from
both fan vibration and wind. Its still more quiet than the old noisy fan
but I could hear the new fan from upstairs. The mounting is solid to joist
per instruction and the connection to the 3" duct is tight. I suppose once I
close up the ceiling and walls with insulation it would not be as bad. Are
quiet fans really all that quite? Maybe should have purchased Panasonic fans
instead - its the same price.
I was unable to find the specs for the model you metntioned
maybe a letter is missing from the model number?
in any case..........one of the design features of the quieter fans is
the use a a larger duct size.
The quiet ones use a 4" duct & the really quiet ones use a 6"
duct....to keep the air velocities & the back pressure on the fan low.
By using the exisitng smaller duct you are negating some of the quiet
Addtioning most of the quiet fans have some sort of resiliant mounting
system...does yours have that & is it working?.....hard mounting allows
more sound to be transmitted through the framing.
The second floor is above this bathroom. The existing 3" duct runs along the
joists and punch out on one of the outside walls. The 3" duct has a 25' run
and its the flexible kind so more air restriction. There are blockings
between the joists and seems not possible to upgrade to 4" ducts without
tearing out the family room ceiling. Bathroom is small so I don't need a lot
of CFM - perhaps I could reduce the motor speed.
.....hard mounting allows
I expect Bob has already hit on the two prime areas --
Might just try it by disconnecting its outlet from the 3" ductwork
temporarily and see if the noise is reduced. I'm guessing it will be
and to get the benefits of the fan you'll need to install larger duct.
Don't see could go wrong in going to 6" even although probably no
real advantage as the outlet is 4". In doing so, though, avoid the
flexible ribbed wall stuff as the rough surface adds to turbulence
which raises noise. If you absolutely need some for a connection, make
it as short as possible. And, of course, make sure the ductwork is
mounted securely so it doesn't add its own vibration.
If, otoh, what you then hear is actually the fan itself running and not
airflow, I'd look at adding some dampening between it and the joists.
A section of tire sidewall is one of my favorite things to use for such
Finally, if you do add insulation or other sound-deadening around it,
be sure to not block any necessary air circulation for cooling of motor
and lights, if any. Don't want a quiet installation to become a fire
none of that matters, it all depends on what you are sticking in the
depends on how bad the farts are
you're wife bought the fan? in that case I would say.. this is her way
of telling you how rotten you smell
like.. something crawled up inside you and died jack
I am not familiar with the Broan fans, but we installed a few Panasonic
fans in our house. They're the type with the large squirrel cage style
The smaller (70cfm) fans are virtually silent in operation. We have one
that runs continously as part of our house ventilation system, and unless
you are standing directly under it and the house is completely silent, you
can't hear them running at all.
We have one larger (110cfm?) Panasonic fan in our master bath, and while it
is louder than the smaller fans, it's only loud enough that you can tell
it's running. It is still MUCH quieter than the fans we had in our previous
In our case, we have 4" ducting. Two fans are close to the exterior walls,
so I have flexible ducting connecting the fan to the wall vent. One of the
fans is in the center of the house, so I installed rigid PVC piping on the
long straight runs to minimize turbulence. It only uses flexible ducting at
each end to connect the fan and wall vents.
Your fan would most likely be quieter in your test because it's not
transmitting sound through the framing, and there's no restriction on the
air flow. Reducing to the smaller duct size will make the fan work harder
and increase noise from the air turbulence. If there's no kind of rubber
isolation in the fan, any vibration will probably transmit through the
ceiling framing and make it sound even louder. Another possibility is you
may have knocked a balance weight out of position or off entirely?
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.