DIY Home Improvement Forum banner

multiple bathroom exhaust fans into one vent??

22807 Views 9 Replies 2 Participants Last post by  JulesB
Back to working on my bathroom venting issues. Would like to run three seperate bathroom exhaust fans into one vent pipe exiting out an attic gable wall.

Longest run (50cfm) would be approx. 16' with one 90 and two 45's. Second (70 cfm) would be 13' with the two 45's and the closest (50cfm) would be 4' with one 90. (the 16 hooking into the 13 at approx. 12, both hooking into the 4 at 3, if that makes any sense)

Questions (numerous):

-can I even do this? possible restrictions? local code issues?
-size of pipe runs?
-how to T or Y into the run? special duct pieces?
-special backflow dampners?
-three seperate fans, or use one (variable speed?) near the exit?
-referals to companies who make such a setup?/special parts

I'd prefer just one fan at the exit, for several reasons. Quieter (hopefully). Easier to get centering location in each of the rooms, and can use custom vent covers. (I can build duct boxing myself).

Any and all help/references greatly appreciated.

1 - 6 of 10 Posts
I would go with a single unit like that is used in commercial structures. One fan pulls for all spaces needing venting. Better than putting in multiple units, plus will be quieter.
I would prefer that. Just don't know the "rules" of doing so. Do you need a variable speed fan? Are there any rules on dampners/backdraft?
Seems if there are, then there has to be a control unit to monitor the various on/off configurations. With one draw, wouldn't duct size be more critical? Am I over thinking it??

thanks for chiming in,
I guess what I'm concerned with is, if it's just one fan, set inline, and you have it switched at each of the (3) locations, what keeps it from drawing your conditioned air out of locations 2 and 3 when you're only "stinking" up location #1? Electronically controlled dampners? variable speed fan motor? etc.?
I'll do some more googling. I didn't run into any on my previous Broan searches. Makes sense that they would have a setup though.
Found close to what I'm looking for.....
Aldes Ventzones

anyone out there ever use these? Other brands/recommendations?
I love the concept. My only reservation is the fan speed/cfms. 2 of the 3 spaces I have are small. Unless I'm missing something, the fan isn't variable speed? I'd hate to "suck" 171cfms each time I ran it in a 4x6 1/2 bath.
Or does the restrictors keep the cfm's down?

Thanks again,
Best thing is to get in touch with an environmental engineer that can take the blueprints of the home, or come in to get the numbers to do the calculations for the best option.
have basically done that, when I had HLA done for sizing hvac.
Plan to contact manufacterer monday morning to discuss. I believe they use some form of inline restrictor vs. variable speed motors.....
  • Like
Reactions: 1
1 - 6 of 10 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.