Replies

1. 
   Billy | Jan 26, 2007 07:32am | #1

   Just let it exhaust all the baths.  It won't be on that many minutes per day.  They have electonic dampers but you can install for each bath, but I don't think it's worth it if you are using one fan for 2-3 or perhaps even 4 baths.

   You do need to make sure that all of your fan timer switches are wired to the same circuit.

   Billy

1. 
   BryanKlakamp | Jan 26, 2007 07:41am | #2

   Thanks, Billy.

   Anyone else have any thoughts?"Objects in mirror appear closer than they are."

   Klakamp Construction, Findlay, Ohio

1. 
   BryanKlakamp | Jan 30, 2007 03:11am | #3

   Bump"Objects in mirror appear closer than they are."

   Klakamp Construction, Findlay, Ohio

2. 
   IdahoDon | Jan 30, 2007 04:57am | #4

   Thoughts?  You aren't getting more responses, because the question has been answered.

   Essentially, all the bathrooms vent at the same time.  It sounds wasteful, but most bathrooms have fans that are used much less than they should be.  The timers prevent the fans from running too long, but long enough to actually do some good.  If one bathroom isn't used except for special occations vent grills that are adjustable can cut off any ventilation until you need it. 

   If you do not want all the bath vents going at the same time simply don't use a single fan.  On our current project we have three bath vents that will rarely be used at the same time, although two will be used quite a bit.  We simply have three small Fantec (brand) remote fans, which cost about the same as a larger single unit.  The wiring is about the same, the duct is about the same, only we have three 4" vent penetrations instead of one 6".

   There are probably duct valves that can be wired into the timer of each bath to only allow the bath duct to flow if it's timer has been activated, but the cost is more than simply having individual fans.

   Best of luck.  

   Beer was created so carpenters wouldn't rule the world.

1. 
   BryanKlakamp | Jan 30, 2007 05:08am | #5

   Thanks, Don.

   I used a roof mounted fan that I had purchased 5 years ago and that I didn't want to return at the time. Figured I would use it sooner or later. So I used it for my house when I added another bath.

   I have considered putting a speed control on it that would have it run as slow as possible all the time for some positive ventilation. Then, when someone turns on the exhaust fan switch in either bath, it would go to full speed.

   It does exhaust more air, which helps get the moist air out more quickly. This should reduce the chance for mold in the bathroom.

   I knew that I could get motorized dampers for each run, and that they would cost $100 - $200 each. So you would be right that it would be less costly to install an inline fan for each bath. I might have done that except that I already had this one.

   Thanks again!

   Bryan"Objects in mirror appear closer than they are."

   Klakamp Construction, Findlay, Ohio

2. 
   barmil | Jan 30, 2007 05:38am | #10

   I'm replacing my Fantech this Spring, had it for ten years. I was initially intrigued by the concept, but it turned out to be as loud as the cheap big box fans. Apparently, moving that much air through a four inch ceiling vent creates its own noise, however quiet the fan is itself. I installed a Panasonic in another house a year ago, and it's almost impossible to hear it, even though it's moving 100 CFM. When I can stand to be in the attic again, the new Panasonic in the box in the basement will go in. Plus, it has a light, which is good, since our bathroom lights are by the mirror. I think the Fantech has its applications, like dryer boost over distance, but not for my bathroom. What I need now is a good sidewall vent that doesn't freeze shut when the temp drops twenty degrees overnight. I start my  shower those mornings with this faint whir that says no venting (this tells me that the fan itself is actually quite quiet), and I'm half way through it before the warm air thaws the vent and I then hear the wind tunnel. Since I also open the side window a couple of inches, I get condensation before this happens.

   My Fantech installation was done with 4 inch green PVC to the fan by the attic wall, then a couple of inches to the outside -- as close to the exterior exit and as far from the source as one can get, I believe. The PVC run is about four feet. It's all insulated. I've traced the noise to the ceiling vent, not only for its baffles but also for the anti-backflow flapper that doesn't want to open all the way when it gets lint on it. Should I wish to clean this weekly, I could probably reduce the noise, but I do have enough house maintenance as it is.

   Had my 59th birthday last week, within a couple of retirement, I hope, and I'm into a caregiver situation with my parents. I've decided to quit experimenting with new concepts (it hurts to give up that fun) and stick to those that don't require as much time. Plus, I can spend money now to avoid doing it later when I make golf and travel my vocation and I earn less. So, the Panasonic fan isn't cheap, but I think it'll be around for awhile, as I hope to be.

1. 
   IdahoDon | Jan 30, 2007 06:33am | #11

   The PVC run is about four feet.

   That's your problem!  The fan is way too close to the bathroom to deaden noise.  In these cases a flex duct should have been run out in a big loop before reaching the fan.  Also, the bathroom ceiling should be well insulated to further block the noise.

   I think we've had this conversation before, and it's just as true today as it was a month ago.  Poor installation = poor results.

   Good building. 

   Beer was created so carpenters wouldn't rule the world.

2. 
   barmil | Feb 01, 2007 06:36am | #12

   I guess I could have made some runs around the attic to have more than four feet between the bathroom vent and the fan, but how could you believe that to be an issue? Quiet is quiet. Go away if you don't have physics to support your theory.

3. 
   Billy | Feb 01, 2007 06:59am | #13

   Physics 1:  Structural sound transmission directly from the fan along/through the walls of the rigid duct to the bathroom, which would not occur if even a short piece of flex duct was used.

   Physics 2: Sound transmission through the air inside the duct, which occurs more easily with the smooth PVC walls than with the flex duct walls.

   I'm not saying I love flex duct, but it can reduce sound transmission.  I once dealt with a basement bedroom with the HVAC unit on the other side of the wall, and there was a lot of noise coming through the sheet metal duct.  I replaced the sheet metal with a short loop of good quality flex duct and it cut down greatly on the noise.

   By the way, the noise problem is well known and Fantech makes a sound muffler for you -- see the silencer for 4 inch rigid duct:

   http://www.hvacquick.com/frfnconfig.php?fm=ld&PHPSESSID=2sf5g0j8mvo3p913bul650qso7

   Billy

    

4. 
   IdahoDon | Feb 01, 2007 07:19am | #14

   How's this for physics:  the closer the fan is to the duct grill, the more it sounds like a traditional bath fan.  It's all about getting the noise generated by the fan as far from the grill as possible. 

   For additional rocket science read the manufacturer's literature and they'll tell you exactly the same thing.

     

   Beer was created so carpenters wouldn't rule the world.

2. 
   DanH | Jan 30, 2007 05:16am | #6

   If you use standard in-ceiling fans feeding a common duct, air will blow from one fan to the other. There are one-way dampers built into the fan housings, but they aren't terribly effective.

   However, you purchase stand-alone one-way dampers to place in the ducts coming from each bath. These should eliminate 98% of the backdraft.

   The other option, as you've implied, is to use a single common duct fan that is turned on from either bath. In such a case you could use electric dampers to turn on only the duct "calling" for the fan, but this would create a fairly complex setup. (Not that expensive, but you'd never find someone to wire it up correctly.)

   So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
3. 
   JDRHI | Jan 30, 2007 05:17am | #7

   All rooms are venting at once....which is why it is so important to purchase an adequately sized fan. Make sure to note the cubic feet of all rooms to be vented when when choosing the proper model.

   One thought worth considering...put switches on a three way (or four way/five way as case may be). From time to time it would be nice to be able  turn the fan off from my master bath when one of the kids has left it on in the downstairs powder room.

   Free dovetail & splintie!

   (they're gonna drive the guards bonkers)

    

    

   
   

1. 
   DanH | Jan 30, 2007 05:18am | #8

   I think it's better to just use timers, or humidistats with timer override.
   So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin

2. 
   BryanKlakamp | Jan 30, 2007 05:29am | #9

   My house is less than 1300 SF. One bath is 20' from the other. We pass the one the kids use when we go outside or to the kitchen. Not a problem in my little house."Objects in mirror appear closer than they are."

   Klakamp Construction, Findlay, Ohio