(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 5 of 5

Thread: Bathroom vent fans and ducting

  1. #1
    DIY Member rfsmith48's Avatar
    Join Date
    Feb 2008
    Location
    Colorado
    Posts
    40

    Default Bathroom vent fans and ducting

    Folks,

    I am adding vent fans to 2 adjacent bathrooms. Fans will dump into 1 four inch vent pipe.

    Questions: does anyone make check valves for this type of tubing? (Don't want one running fan to dump into other bathroom) Local hardware store recommended a y-pipe to minimize problem, don't know if that works well or not?

    Thanks in advance.

    Rog
    303 494 0140

  2. #2
    Homeowner Thatguy's Avatar
    Join Date
    Aug 2008
    Location
    MD
    Posts
    1,460

    Default

    Quote Originally Posted by rfsmith48 View Post
    Fans will dump into 1 four inch vent pipe.

    Questions: does anyone make check valves for this type of tubing?
    So each fan will see the equivalent cross section of a 2.8" dia. pipe if they both run at the same time. The backpressure seen depends on the relative length of each leg of the Y. Exterior louvered wall vents act like leaky one way valves but you'd have to modify them for inline use.

    It might work because bathroom fans seem to be oversized; you only need 8 air changes per hour so a 5' W x 7' D x 8' H room only needs 37 CFM.

    If you can pry the "fan curves" from the fan manufacturers this duct network can be analyzed and so your fan performance can be predicted ahead of time.
    Don't forget to undercut the bathroom doors to admit new air.
    Last edited by Thatguy; 11-17-2010 at 05:03 PM.

  3. #3
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    Location
    New England
    Posts
    21,401

    Default

    I'd consider a remote fan designed to handle multiple rooms. Fantech, among others, make some designed for this sort of application. Dampers often leak...you might end up dumping the output from one bath into the other rather than outside and sharing the moisture and smells.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  4. #4
    DIY Member rfsmith48's Avatar
    Join Date
    Feb 2008
    Location
    Colorado
    Posts
    40

    Default

    Guys,

    Thanks for the responses. To clarify:

    1. Primary concern is: One fan running and blowing its output into the other bathroom.
    2. Secondary concern: Both fans running and pushing air into a 4" pipe. This is a lesser problem and low probability for both showers being used simultaneously.

    Still searching for check valves for 4" duct pipe....

    Thanks,

    Rog

  5. #5
    DIY Member rfsmith48's Avatar
    Join Date
    Feb 2008
    Location
    Colorado
    Posts
    40

    Default

    Folks,

    Question answered by buying a fan from Lowes......check valve is included in fan shroud/assembly...

    Rog

Similar Threads

  1. Bathroom Fans: Best way to install ducting?
    By rick15752 in forum HVAC Heating & Cooling
    Replies: 4
    Last Post: 12-15-2010, 08:54 AM
  2. Hooking up two bathroom fans to one vent
    By Jwhitman in forum HVAC Heating & Cooling
    Replies: 4
    Last Post: 04-17-2010, 04:33 PM
  3. Proper way to vent bathroom fans in Las Vegas
    By blargh in forum Remodel Forum & Blog
    Replies: 1
    Last Post: 03-29-2010, 10:51 AM
  4. Can I pipe two bathroom fans to one roof vent?
    By mckeand13 in forum Plumbing Forum, Professional & DIY Advice, Tips & Tricks
    Replies: 5
    Last Post: 05-27-2007, 08:39 PM
  5. Ducting exhaust fans in bathroom remodel
    By LLH in forum Remodel Forum & Blog
    Replies: 3
    Last Post: 05-04-2006, 07:41 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •