Help...have read in the past the exhaust fans in bathrooms generally aren't
that effective. In other words, by simply ensuring the door is left open
after a shower, as much humidity can be removed from the room as an exhaust
I live in Northeastern Wisconsin. Opening a window is not a year round
solution. Am concerned with the efficiency (or lack of) an exhaust fan
during the winter months. I also have a teenaged daughter that believes
it's necessary to blow dry her hair for 20 minutes after her shower. So not
only is the room a bit on the humid side, it gets heated by the dryer.
Would appreciate any thoughts/comments on the subject.
I know in Maryland that they were required by code, and further they were
required to the come on when you switched the main lights on.
To make an intelligent comment one would really have to take a look at your
house to see how well the humidity "drains" w/o a fan or window left open.
One thing to keep in mind is that during the winter the glass in your
windows will be cold enough for that humidty to immediately condense and run
down onto the stool and probably into the window itself. That's never going
to be a good thing.
You have to balance the cost of losing the heated air against those of
possibly having to repaint more often, possibly having your window rot,
possibly having moisture migration into the drywall, etc. etc. etc.
It may be that the way your house's natural ventilation is that you are just
fine not using a fan. On the other hand it may be that your bathroom turns
into a steam room. Tough to tell from here.
While the idea of opening the door while showering may be effective (and
again I don't know the layout of your house) the first time a guest happens
to spy your daughter stepping out of the shower may put an end to that
The heat of your daughter's hair dryer isn't going to change the siutation
any. All heat does is convert water to gas so it can escape more easily.
If there is nowhere for the gas to escape to, i.e. insufficient ventilation,
it's going to recondense in that room as soon as the temperature goes back
down 20 minutes later.
Lots of variables here but they don't insist on bathroom ceiling fans in the
code for no reason.
good luck :D
kzin has posted a useful discussion.
I grew up in Menomonie in Western Wisconsin.
I think relieving the humidity from inside a home is a good thing.
There are a number of competing concerns that include energy,
condesation on interior surfaces and within walls.
Al, I'm not sure what you're asking. Do you have an exhaust fan now?
Are you concerned that it does not do enough to vent humidity from the
room? Are you concerned that it wastes heat in the winter? Are you
thinking that opening the door after the shower is a substitute for
having a fan?
Bathfans are required if there is no window where I live.
Installing one that is sized properly is one of the keys. I just put in a
100 cfm fan in a 4X10 room.
It has trouble with the whirlpool tub.
Installing a fan will cause you to loose some heat in the winter. Can not be
helped. Even if you do not run the fan long.
Getting rid of humidity is an issue for me. I prefer it dryer to wetter.
Bathroom fans are effective and that is why they are required by code in
most bathrooms that lack a window. The airflow (cfm) should be sized to the
room so a bigger room needs a bigger fan. You can get ones with heatlamps
or heat coils built in and I suppose you could even attach one to a humidity
sensor or thermostat so that it only disposes of excess heated air (though I
don't think this is common practice)
Humidity is not the only use for the fan. Don't forget those noxious odors
we all produce.
In order for an exhaust fan to be effective it must have "Make up air". The
air that is removed by the fan must be replaced in order for the air to
move. If you put an 80 cubic feet per minute fan in a totally sealed room,
it will not do anything because there is no air coming in to replace the air
that is being pushed out. This can be resolved by opening a window
somewhere in the house, installing a make up air vent, installing a fresh
air vent to your forced air furnace, etc.
In other words, by simply ensuring the door is left open
Also do not forget that if the humidity is left inside the house in the
warmer monts makes the air conditioner work harder to remove the humidity.
Part of the colloing effect of airconditioning is removing humidity in the
air, A big deal down here in the humid southeast.
A little more costly but some swear by putting in a heat exchager to
warm/cool the makeup air when using a makeup air system as metioned in the
Around here they sell an awful lot of humidifiers for use during the
winter, so I don't think humidity in itself is a bad thing. It seems
the problem is that you have too much of it in one small area. If I
were building the ideal home, I think I would want a bath fan that fed
the humid air into the heating ducts during winter, and outside during
summer. The "noxious odors" can be handled by getting a toilet with a
Not safety, rather it is needed to keep the room from rotting and
molding with all the high humidity most baths get. That is also why this
is best left to LOCAL codes since local conditions make a bid difference in
So, your saying that if the code requires it, and the homeowner can't do
anything about it, then the contractors's bids for installing fans are
higher than they would be if the homeowners could choose to live without
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