I have a couple questions regarding ducting exhaust to the gable ends of my home.
Two types, first would be the bathroom vent fan exhaust run and the other is the dryer vent.
How far can I run the ducts in unconditioned space before I have problems? What types of problems could I expect to see in this run which would be a worst case scenario:
Bathroom exhaust run 30′ total in unconditioned space. It would travel 24″ vertically, take a 90 degree turn and then run horizontally the other 28′ to exhause out the gable end of the house.
We have other options, but the one posed above is the most aesthetically pleasing.
What else should I watch out for with these runs? (Two bathrooms, one dryer).
Replies
The code dryer vent is 25 ft equivalent distnace. Each 90 elbow counts at 5ft. And this using rigid ducting with only a minuimal amount of flex AL for the connection.
However, manu manufactures spec longer runs. And you can also get dryer vent boost fans if needed for longer runs.
For the bath vent fans check the specs. You might need to go up a size or two for the longer runs.
So basically you're saying, "Read the instructions dummy"
:)
Sometimes the simple things evade me.
The two baths you can join together in the attic and go to one tube use a "Y" where they come in and up size. You will need to insulate it so it won't condensate. just a note the dryer isn't supposed to be over 25 '.
My mechanical guy run the bath fans in insulated flex, and the dryer in rigid ducting with R-5 foil-faced FG wrapped around it. I ask him to go high immediately and then slope the duct down to the vent cap, so that any condensation or moisture in the pipe drains out, rather than sitting level or running back to the appliance.
A "Dryerbox" makes for a nice dryer install with miminal flex pipe and minimal chance of crushing it.
I have done one very long dryer run in the attic, using a pressure sensing booster fan. Easy install, and hopefully the fan will work forever. In that case the owner's instructions for yearly maintenance included going into the attic with the dryer running to make sure the fan is still running too.
Brian you already have the basic answer on the dryer line, but i'll add my pennies worth on the shower duct.
Look into the FAntech or Panasonic units that remove the actual fan from the shower a distance, and then blow it out. This gives you a much quieter exhaust and lets you size the fan to the load. The folks at either comapny can help you pick the right unit. Even if you are going too ffar, you can step it up with two blowers on the line, separated form one another.
With such a long run, I would suggest that you wire it to a delay shutoff switch so that it keeps running for fifteen minutes to evacuate the moisture out of the line and you don't have condensate collecting in line and growing furry little pets related to the kind you used to have in the refridgerator when you were single.
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All good advice guys and I really appreciate it. Sorry for not replying sooner. Busy, busy, busy!
Fan Tech has a built in delay switch, and a static pressure activated switch, both standard on their units.Regards, Scooter"I may be drunk, but you're crazy, and I'll be sober tomorrow." WC Fields, "Its a Gift" 1934
In my area (a bit warmer than Boston, but not much) just nailing off the bath exhaust duct on a rafter next to (and slightly below) a through roof vent almost always works.
Hi Bob. I'm not sure I understand... this is all very Greek to me. Are you saying to let it vent out the ridgevent? Not sure what you meant by a "through roof vent".
I'm leaning towards one of those units that will exhaust all three of our bathrooms from one remote (attic) location. The two new baths are stacked over the original 1st floor bath and all are, unfortunately, on the front of the house. We're trying to minimize the number of roof and gable penetrations for aesthetics.
Thanks for your informed advice though.