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-   -   multiple bathroom exhaust fans into one vent?? (http://www.diychatroom.com/f17/multiple-bathroom-exhaust-fans-into-one-vent-106506/)

JulesB 06-03-2011 04:50 PM

multiple bathroom exhaust fans into one vent??
 
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.

Regards,
Jules

gregzoll 06-03-2011 05:39 PM

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.

JulesB 06-03-2011 07:42 PM

Quote:

Originally Posted by gregzoll (Post 660628)
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,
Jules

gregzoll 06-03-2011 09:14 PM

It depends on how many baths or spaces that you are controlling. Broan, Panasonic, and a few others have them. Basically the motor unit sits in the attic, and pulls the air through the ducts from each space. As for turning the fan on, you could set it for when the light goes on (ie relay), or through a ir spot that would tell if someone enters or exits the space.

JulesB 06-04-2011 08:26 AM

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.
Thanks,
Jules

JulesB 06-04-2011 10:17 AM

Found close to what I'm looking for.....
Aldes Ventzones
http://www.iaqsource.com/product.php...&category=2145

anyone out there ever use these? Other brands/recommendations?
thanks.

gregzoll 06-04-2011 11:18 AM

That would work for the zones. This is what you need to get http://www.iaqsource.com/category.ph...?category=2152 They come in 2 to 5 room setups. I know that they are expensive, but when you factor in the costs for separate units, it justify spending that. I would go for it if I had two baths in my house, especially when you do not want to hear the fan running when someone uses it.

JulesB 06-04-2011 07:11 PM

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,
Jules

gregzoll 06-04-2011 09:12 PM

You would have to check out the spec's. 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. It would be money worth spent, than trying to figure on your own and end up with the wrong equipment that is either undersized or oversized.

JulesB 06-05-2011 07:15 AM

Quote:

Originally Posted by gregzoll (Post 661267)
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.....


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