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Old 05-08-2012, 03:00 PM   #1
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Bathroom Exhaust Fan Advice Needed

I have 2 bathroom separated by a common wall. Room sizes are ~10’ x 7.25’ (80 CFM) and 4.75’ x 10.75’ (60 CFM).

I can either install 2 separate fans each with a duct exiting the side of the house, or 1 in-line fan with a single duct to the side of the house (I saw this alternative in a Panasonic ventilation catalogue). For an in-line fan, I would use a 3 way switch so that it could be turned on from either bathroom.

1. Is either alternative ok? Or are there good reasons not to use an in-line fan for both bathrooms?

2. If I use 2 separate fans, can they both be vented through a common duct to the outside? If not, why not?

3. If I use PVC for the fan duct work, do I need to be concerned about condensation on the ducts and insulation around them in the attic? Ditto for galvanized aluminum?

4. And what fans are of better quality - Panasonic, NuTone, Broan?

Thanks - the last item I need for my bathroom remodeling.


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Old 05-09-2012, 04:52 AM   #2
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All three as well as Fantec offer quality fans. Select a quiet fan or it does not get used. Do not control with a three way switch. Use a switch that keeps the fan on for 20 minutes after leaving the bathroom or use a humidistat.

One fan ducted through the roof is a good way to go. Controls are built-in for two switches.

You need to use insulated duct work in any unconditioned space to avoid condensation on the duct.

Size the fan to remove enough moisture based on size of the room. For two rooms use at least a 190 CFM fan.


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Old 06-03-2012, 08:53 AM   #3
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This is not my expertise, but just thinking.........Using one in-line fan and one duct as an exhaust will require a duct "Y" before the fan to go to each bathroom. You will need a bigger CFM fan to remove sufficient air from both bathrooms to be efficient.
I do know it's not good to use PVC as it will cause condensation and static electricity.
I did this on a shop dust extractor one time and the fire marshal had a fit.
Use an insulated flexible hose or insulated metal duct.
I can't see a reason why a 3 way switch couldn't be used although as I said this is not my expertise.
What ever you do , buy the best fan[s] you can afford.
When my youngest son was a teenager it took nothing short of all the windows open and a "Dayton 500 CFM shop fan" to remove the fragrance of his daily dump.
"I'm not as green as I am cabbage looking"
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Old 06-04-2012, 10:12 AM   #4
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My advice would be go with 2 fans. Panasonic 110 cfm.

Amazon has them fairly cheap from time to time. $149 sometimes. I think right now they are $160 or so.
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Old 06-04-2012, 02:15 PM   #5
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I just installed a Panasonic in my folks' house. Very nice. Well thought out installation, and very quiet. Some of the big box fans are LOUD. Look for something less than 1 sone. (Unless you like the noise. Some folks do.)
I installed two of the fans from Aura Vents in my house. Also VERY quiet, since the fan motor installs on the roof and pulls air rather than sitting in the ceiling. All you hear is the air entering the vent. You'd have to call them about venting thru the wall.
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