Bathroom Exhaust Fan with a 30 foot duct run to gable

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Art

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Jul 9, 2019
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nj
Hi Everyone,

I purchased a house a year ago and noticed that the bathroom fans exhaust to the attic (its an older house). I want to avoid drilling holes in the roof since I just had it done. So I wanted to run the exhaust hose 30 feet to a gable and exhaust out that way. The smaller bathroom is 8Lx4Wx8H and the bigger bathroom is 10Lx6Wx8H. I was going to get a 110cfm fan for the bigger bathroom and a 80cfm for the smaller bathroom. As for the duct i was going to use a Insulated flexible duct R6 silver jacket. Is 30 feet to long? Also would a centrifugal fan be better then the ceiling one? Any help would be greatly appreciated.
 
Definitely use insulated duct. And cut a hole in your roof and vent to the outside. To be honest I don't know if it's legal in some places to terminate to attic vents but in my opinion that's just lazy and a very very unprofessional
 
Art said:
Hi Everyone,

I purchased a house a year ago and noticed that the bathroom fans exhaust to the attic (its an older house). I want to avoid drilling holes in the roof since I just had it done. So I wanted to run the exhaust hose 30 feet to a gable and exhaust out that way. The smaller bathroom is 8Lx4Wx8H and the bigger bathroom is 10Lx6Wx8H. I was going to get a 110cfm fan for the bigger bathroom and a 80cfm for the smaller bathroom. As for the duct i was going to use a Insulated flexible duct R6 silver jacket. Is 30 feet to long? Also would a centrifugal fan be better then the ceiling one? Any help would be greatly appreciated.
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Exhaust fans should have performance ratings for recommended areas to be exhausted, which you may have already checked.
Sounds like your main question is if 30 feet is too long a distance. You can either consult with the manufacturer of the fans(if it's not already addressed somewhere in the installation instructions, like it should be, OR you could look up how it would be designed. For example, fan cfm at inches of water column vs pressure losses through 30 feet of x" duct. Or better still, find an HVAC forum that could answers your questions and concerns easily.
 
First thank you everyone for all your responses and help really appreciate it. Diehard I called the manufacturer of the fan I was looking to get and they said they don't see that as a problem because their fan can support a 90 foot run. I just figured reach out in this forum to see if there was anyone that has done a run like that or if it was a big no. I have Googled for a while now and just can't get a straight answer on what is considered a to long of a run.
 
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