I am remodeling an old 2 story house, and am installing 4 baths, 2 up and 2 down, 2 above the other 2. I want to install only 1 fan for all 4 baths, in the attic. Is this practical? If so, what size fan and motor should I look for? I'm thinking of venting it thru the roof, before I have the roof redone.
Exhaust fan for multiple baths
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"1.) First find the volume of the bathroom. Volume = length x width x height
2.) Find the CFM (cubic feet per minute). Volume / 7.5
3.) This CFM is the minimum airflow required to achieve 8 air exchanges per hour.
Example: Volume = 10 x 6 x 8 = 480
CFM = 480/7.5 = 64
In this example you would only purchase a fan that has a CFM listed on the box greater than 64."
Ductwork/fitting losses may be significant for this application and if you really want to do it right you need the fan curve.
2.) Find the CFM (cubic feet per minute). Volume / 7.5
3.) This CFM is the minimum airflow required to achieve 8 air exchanges per hour.
Example: Volume = 10 x 6 x 8 = 480
CFM = 480/7.5 = 64
In this example you would only purchase a fan that has a CFM listed on the box greater than 64."
Ductwork/fitting losses may be significant for this application and if you really want to do it right you need the fan curve.
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I guess you should price out all the options in view of the cautions. I s'pose you'd also need to balance the bathroom vents with dampers, just like a miniature HVAC duct system.
And buy a digital readout CO detector.
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Where are you located?
Arround here you don't want a lot of air being sucked out of the house in the winter
And in some areas the same is true in the summer - as you will be pulling in hot humid air
Arround here you don't want a lot of air being sucked out of the house in the winter
And in some areas the same is true in the summer - as you will be pulling in hot humid air
Thanks a million for the input! It will probably more practical for me to put individual fans in each bath! I can make the vent pipes of the 2 downstairs baths to share an exterior exhaust vent through the outside wall, which is frame, with vinyl siding. The upstairs vents can go into the attic, and share an exhaust vent thru the roof.
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If they "share" a vent to the outside then it is possible for one bathrooms fan to push air into the other bathroom :huh:
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