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Posted by JoeSpareBedroom on September 23, 2007, 10:14 am
>>> 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.
>>>
>>> John
>>
>> 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
> air problem.
>
> 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
> winter.
>
> --
> Joseph Meehan
>
> Dia 's Muire duit
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.
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