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  1. #1
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    Default bathroom exhaust vent

    Hey,guys could use some advise on bathroom fan.Im working on a 1926 two story home so putting fan in ceiling an venting it outside will take some work since there never was a fan in bathroom to begin with.seems much easier to install a remote fan below bathroom in basement run short duct up to the baseboard with a register an then wire it in.but is having the vent intake so close to the floor make it work poorly? what do think stupid idea or could it work?

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  2. #2
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    Jul 2007
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    Chicago
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    Default Re: bathroom exhaust vent

    Quote Originally Posted by tony voss View Post
    Hey,guys could use some advise on bathroom fan.Im working on a 1926 two story home so putting fan in ceiling an venting it outside will take some work since there never was a fan in bathroom to begin with.seems much easier to install a remote fan below bathroom in basement run short duct up to the baseboard with a register an then wire it in.but is having the vent intake so close to the floor make it work poorly? what do think stupid idea or could it work?
    Most humidity rises towards the ceiling but it sure would be better than nothing.
    It would satisfy code.
    Curious to see what others say.


  3. #3
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    Mar 2007
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    Default Re: bathroom exhaust vent

    [quote= Bob Elliott] Most humidity rises towards the ceiling but it sure would be better than nothing.
    It would satisfy code.
    Curious to see what others say. [quote/]

    "Humidity rises at ceiling" is a bit misleading.

    While the ability air to hold moisture increases with temperature, The moisture content of air migrates to areas of lower vapor pressure in any direction. Vapor pressure migration in air is very fast. (faster than temperature). As inspectors we've all witnessed moisture migration through sheet rock and other materials, So exhaust of moisture from a vent that is at a lower than ceiling level in the bathroom will work fine.

    The trick is to size the fan for 10-15 air changes an hour, and allow free space under the door for make up air. As the volume of air in the bathroom is replaced with dryer make up air, the moisture will migrate to the dryer air and be exhausted.


  4. #4
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    Default Re: bathroom exhaust vent

    [QUOTE=Ken Amelin;153366]
    Quote Originally Posted by Bob Elliott
    Most humidity rises towards the ceiling but it sure would be better than nothing.
    It would satisfy code.
    Curious to see what others say. [quote/]

    "Humidity rises at ceiling" is a bit misleading.

    While the ability air to hold moisture increases with temperature, The moisture content of air migrates to areas of lower vapor pressure in any direction. Vapor pressure migration in air is very fast. (faster than temperature). As inspectors we've all witnessed moisture migration through sheet rock and other materials, So exhaust of moisture from a vent that is at a lower than ceiling level in the bathroom will work fine.

    The trick is to size the fan for 10-15 air changes an hour, and allow free space under the door for make up air. As the volume of air in the bathroom is replaced with dryer make up air, the moisture will migrate to the dryer air and be exhausted.
    Must be a tough trick judging by the weak exhaust fans I see most of the time.I especially hate the passive vents in old high rises since there is no way to upgrade due to location but thanks for the detailed rundown.
    I agree.


  5. #5
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    Columbus GA
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    Default Re: bathroom exhaust vent

    Tony

    There are fans that mount and exhaust through an exterior wall. That is if you have an exterior wall.

    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

  6. #6
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    Default Re: bathroom exhaust vent

    [quote=Bob Elliott]Must be a tough trick judging by the weak exhaust fans I see most of the time.I especially hate the passive vents in old high rises since there is no way to upgrade due to location but thanks for the detailed rundown.
    I agree.[quote/]

    Not that difficult to achieve. A 6ft X 10ft bath with 8 ft ceiling has 480 cu.ft. @ 10 air changes per hour = 4800 cu.ft./60 mins per hr = 80CFM fan.


  7. #7
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    Default Re: bathroom exhaust vent

    [QUOTE=Ken Amelin;153372]
    Quote Originally Posted by Bob Elliott
    Must be a tough trick judging by the weak exhaust fans I see most of the time.I especially hate the passive vents in old high rises since there is no way to upgrade due to location but thanks for the detailed rundown.
    I agree.[quote/]

    Not that difficult to achieve. A 6ft X 10ft bath with 8 ft ceiling has 480 cu.ft. @ 10 air changes per hour = 4800 cu.ft./60 mins per hr = 80CFM fan.
    Personally with the amount of growth I see(mold in grout joints) what may look good on paper(your specs) is not enough and I would like to see exhausts that pull your hair straight up.


  8. #8
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    Default Re: bathroom exhaust vent

    "I would like to see exhausts that pull your hair straight up."

    You mean like this

    YouTube - Broan combover commercial

    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

  9. #9
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    Chicago, IL
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    Default Re: bathroom exhaust vent

    The problem is often not the general humidity level within the bathroom, it's the condensation on the ceiling immediately above the shower/tub.

    In my experience a ceiling fan is required to deal with that condensation, and the placement of the fan is critical to its effectiveness - its not unusual for me to be asked to discover the cause of a "ceiling" leak in a large bathroom that is in fact just condensation at the ceiling even though there is a operational ceiling fan just a few feet from the shower/tub footprint.

    This may seem like a common-sense observation, but I'm occasionally paid to make it to homeowners, and sometimes even have to persuade them to discontinue the use of the shower for a few days so I can come back and demonstrate with IR and /or moisture meter readings that moisture levels at the ceiling have in fact returned to ambient.

    Michael Thomas
    Paragon Property Services Inc., Chicago IL
    http://paragoninspects.com

  10. #10
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    Chicago IL
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    Default Re: bathroom exhaust vent

    Having done this install more times than I can count, I'm not understanding how you think it would be so difficult or more difficult than the basement duct version. I used to know a developer who loved putting one right by the back of the toilet. After a few years, he came to see that for some reason they rusted out like crazy.
    Install the ceiling model or a wall model. Forget the low install, it won't save you anything. If you do go with a low model, provide GFCI protection for it.

    www.aic-chicago.com
    773/844-4AIC
    "The Code is not a ceiling to reach but a floor to work up from"

  11. #11
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    Default Re: bathroom exhaust vent

    Quote Originally Posted by Rick Cantrell View Post
    "I would like to see exhausts that pull your hair straight up."

    You mean like this

    YouTube - Broan combover commercial
    Good one.


  12. #12
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    Default Re: bathroom exhaust vent

    Good one.

    I have my moments

    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

  13. #13
    Join Date
    Oct 2010
    Location
    Tolland, CT
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    33

    Default Re: bathroom exhaust vent

    Quote Originally Posted by tony voss View Post
    Hey,guys could use some advise on bathroom fan.Im working on a 1926 two story home so putting fan in ceiling an venting it outside will take some work since there never was a fan in bathroom to begin with.seems much easier to install a remote fan below bathroom in basement run short duct up to the baseboard with a register an then wire it in.but is having the vent intake so close to the floor make it work poorly? what do think stupid idea or could it work?
    If the bathroom is on an outside wall, why not put a wall vent in? or if you open up the ceiling you can run duct to the outside wall that way.

    Mike


  14. #14
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    Sep 2010
    Location
    taylor mi
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    6

    Default Re: bathroom exhaust vent

    Thanks for all the input,we decided on putting it high on wall an exit outside its a little extra work but worth it thanks again


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