Vents to roof or wall?
Need some advice. I have to run new vents for a dryer 4″, a bathroom vent 4″, and my kitchen downdraft vent 6″. All are nearly in the middle of my house so the closet location to vent to is my roof, which I’d rather not do since it is a tile roof and introducing more spots for leaks cannot be good, and all vents will be in the most visible part of the roof from the ground.
To vent them to the nearest wall would increase their length, but it wouldn’t involve any extra elbows, actually less bends. The other benefit is the wall is where all the mechanicals currently are, and the least visible side of the house, I would very much prefer the vents there.
Will I have any issues if I vent to my wall?
4″ Dryer vent (unknown model, haven’t purchased yet)
wall: 6′ up 25′ over, 1 bend
roof: 10′ up 7′ over, 2 bends
4″ Bathroom vent (Panasonic FV-08VQ5 80 CFM)
wall: 0′ up, 30′ over, 1 bend
roof: 6′ up 2′ over, 3 bends
6″ Kitchen vent (iPower GLFANXINLINE8 745 CFM)
wall: 8′ up 34′ over, 2 bends
roof: 15′ up 6′ over, 3 bends
Well after some digging I found this for the bathroom vent, it looks like at even 80′ of 4″ duct it will still do over 60 CFM, which is plenty for me, so I guess I’m good to go. ftp://ftp.panasonic.com/ventilationfan/fv08vq5/fv-08vq5_2012_submittal.pdf
For the dryer I found conflicting information, some codes say max 35′, and some 25′, but it says if the dryer manufacturer says you can do longer then that is what you can use. I just found some info, I think I’m good, this Samsung dryer says 4″ duct length should be less than 80′ with 0 elbows, 47′ with 3 elbows. A Whirlpool unit I found is 64′-27′, and they have a long vent model that can vent through 160′!
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Replies
Have you looked into heat pump dryers? They have no vent. For a long vent, it will be impossible to clean it and all that lint can be a fire hazard.
I have a heat pump dryer in my home, and it works as well or better than the traditional vented dryers I've owned in the past.
Jimmy,
Long dryer vents can be a problem because of lint build-up. This problem is best addressed at the design stage. (In other words, a laundry room should be located in a room with an outside wall.)
Most rooms have windows, which means that most rooms have at least one exterior wall. Your situation is a little unusual.
Kitchen exhaust ducts can sometimes get clogged with grease, so shorter (cleanable) ducts are always best.
When it comes to static pressure issues arising from long ducts, the usual solution is to upgrade to a larger duct diameter.
-- Martin Holladay