Our two-storey house has a washroom on main floor, and it has no exhaust
fan. Don't want to make a fan on exterior wall (direct vent out), as our
winter is too cold.
I'm thinking to place a fan into interior wall, and get duct up to attic
inside drywall, then vent out from roof. I wonder if this is feasible. Are
there exhaust fans thin enough to fit into interior wall which is only 4-5"?
Is this too big a job to make through from main floor to attic (e.g. drill
holes on 2x4s)? If doable, I may pay to get an expert to do it.
Any input appreciated.
Can't install ceiling fan?
Here it is cold in winter as well(Calgary Alberta). Ceiling fan is
vented outside between floor joist through wall. ducting is insulated.
Exhaust has a flaps (one at fan box, one at the wall which opens only
when fan is on.
Why do you need a fan? I have 2 1/2 baths and a fan in each, but I
only use the one in the room where visitors take hot baths or showers.
And when I use some terrible poison, which is a about every 5 years
for one hour.
In the powder room on the main floor, I unplugged the fan and haven't
used it in 24 years. (0ne fan came with a wall switch and I put a
switch for the other fan when I put in a wall light.)
If you insist on putting one in, put in a pull chain switch or a wall
switch, so visitors can turn the damn thing off. I'd rather do my
business or wash my hands in a public bathroom with no fan or a
distant fan than listen to the racket that even quiet home fans make.
The fan is no way to make guests feel at home.
(For the first 36 years of my life in 2 houses and 3 apartments every
bathroom had a window.)
I'd much rather listen to a little bit of noise from a bathroom fan
than smell the stink for two hours from whoever used the bathroom
before me. Or are you going to tell us your sh** don't stink? Plus
many bathrooms can wind up with moisture damage problems from excess
moisture from showers without having proper ventilation.
There are plenty of fans that are very quiet. All you have to do is
pay $75 - $100 or so, instead of the cheap $30 builder models. Look
for the SONE rating.
John, I think you should put the fan on an exterior wall. Yes, it
could be done like you describe but this approach has several
disadvantages: first, you will have a lot of piping and thus friction
loss. Worse, the vertical exhaust out your roof will be prone to
condensation--this will be exacerbated by the distance from the fan--
as the exhaust air cools, it will be more prone to condensation. This
condensation is going to run right back into the house and cause all
sorts of problems. I once put in a through-the-attic bathroom fan vent
and I never did successfully stop it from dripping in extreme cold
(-30 F). I had it well insulated, but there is of course no way to
insulated the portion that pops out of the roof. Further, you will
have a heat loss from your bath fan no matter where you put it. With
your tall pipe to the roof idea, it may even be worse because you will
create a draft situation. Put it on the wall!
I agree. The wall exhaust should have a flap on it to reduce the cold
Note: no matter what, when you use an exhaust fan, there is one cubic
foot of outside air coming into your home for every cubic foot of air you
are exhausting. I like being about to exhaust or not. I use the exhaust
more during temperate seasons and less during hot humid summer or cold
This depends on the house, of course, but here, if the heat's just kicked on
in the morning, it usually runs a bit longer than a shower. No need for the
fan. The bathroom stays dry. I'm talking about HERE. May not work in other
houses, with other routines.
Have to agree with possibility of condensation problem, especially in
cold cool climates and especially with a vertical run of the exhaust
duct. In an extreme case have seen moisture drip back into bathroom!
It doesnt do the fan any good either!
We initially ran duct with slight upward slope (as recommended);
condensation problems within duct that dripped back onto ceiling of a
bedroom caused us to change that to a downward slope. Nowadays slight
icicle forms on the lower lip of the duct outlet. No condensation/drip
problems. Arrange your joins in the duct so that moisture travelling
towards outlet drips over the joins into next section!
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