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Venting up vs out for bathroom, kitchen

4K views 12 replies 5 participants last post by  hvaclover 
#1 ·
I am a little worried about venting UP for the bathroom and kitchen exhausts... just worried about getting on the roof and doing the flashing correctly, such that it does not leak, etc. The horizontal one seems more straight forward and I've done out the side exhausts before with no problem.

For the kitchen we'd have the exhaust on the front side of our house and it is sort of ugly. Probably not a huge factor but a factor...

Is there any disadvantage to going vertical vs horizontal?

For the bathroom it would be significantly longer to go sideways and I'm worried about water condensing and pooling?

For the kitchen it would be about the same length. I was going to use hard duct.... insulated for the bathroom, not for the kitchen.

For the bathroom, I happened to have a very powerful FanTech fan lying around I could use rather than the 100CFM version that came with the kit we bought. We got the FanTech bathroom kit, but I'v egot an fantech's most powerful 6" inline duct fan, if a more powerful fan is going to help the situation with regard to extra length....

Thoughts?
 
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#2 ·
Can you not vent to the attic instead of going outside with it? If the attic is vented, it shouldn't be a problem.

I used closed cell spray foam to insulate my house and attic. The attic is completely sealed to the outside, so I had no choice but to vent outside. I ran my vents through the roof. It was a new construction thouh, so the roofers flashed around it properly.

If you don't think you can do the proper job doing it vertically yourself, I'd just vent it horizontally out a wall.

I've seen kits that allow you to vent outside and hide the vent in your soffit.
 
#3 ·
Can you not vent to the attic instead of going outside with it? If the attic is vented, it shouldn't be a problem.
Don't vent bathrooms into your attic. In the winter the water vapor from your bath will condense on the surfaces in the attic causing all sorts of problems (even if the attic itself is vented)..

And kitchen -> attic, I can't imagine.. your attic would smell like fried chicken forever and any grease, etc that managed to get into the vent would just be sitting around up there.

I've seen kits that allow you to vent outside and hide the vent in your soffit.
That sounds promising...
 
#4 · (Edited)
Yes, no venting into attic spaces. In the cold climate where I am I've heard many stories of folks that rotted plywood, etc. from all the moisture condensing.

Venting vertically is not a problem, just make sure there are no dips in the piping to allow condensation to pool. A slight pitch down to outside might be good.

I agree with your concerns that venting to the roof can cause potential leaks if not done right. When I had my roof replaced recently I had two put in. That's the right time to do it to be sure there will be no leaks.
 
#5 ·
I am not going to vent to the attic - that is nuts.

At this point, our attic is such a duct nightmare - we've got about 13 ducts lying all over the floor... that I cannot really see the harm in throwing another one down and venting horizontally.

If/when we ever remodel, the entire HVAC system is going to have to be moved so I do not think a little kitchen duct is going to be the determining factor of anything.

What do you guys think of this "SEMI RIGID" duct stuff from Deflecto at Home Depot. It is quite rigid, not to be confused with either flex duct used for heating/a/c or flex duct used for dryer vent. I think it would make my life so much easier and I've found it in a 7" diameter.
 
#7 ·
I am not going to vent to the attic - that is nuts.

At this point, our attic is such a duct nightmare - we've got about 13 ducts lying all over the floor... that I cannot really see the harm in throwing another one down and venting horizontally.

If/when we ever remodel, the entire HVAC system is going to have to be moved so I do not think a little kitchen duct is going to be the determining factor of anything.

What do you guys think of this "SEMI RIGID" duct stuff from Deflecto at Home Depot. It is quite rigid, not to be confused with either flex duct used for heating/a/c or flex duct used for dryer vent. I think it would make my life so much easier and I've found it in a 7" diameter.

Good point, On cold nights the Methane gas from toilet odors can hang in the attic and seep into the occupied space . As the cold air the Methane is riding it's way in to a bed room who do you think will be blamed for breaking wind?
 
#9 ·
I have to say I am very upset with the adapter for the exhaust on me GE PROFILE microhood... THEIR adapter does not fully cover the exhaust port. Is this normal???? I've got air rushing behind where my boot presses up against the rear of the cabinet... not really accessible to foil backed tape.
 
#10 ·
Well I am done with the kitchen, on to the bathroom.

MY question is should I go up or out, again.

We are in very tight spaces here, and either way if I go up or out, I'm going about 2 feet. The only reason I would not go horizontally is because I am worried about condensation build up. Is this going to be an issue if I insulate the ducts and fan (in line), or will I still need to install a drain on the bottom of the fan housing? To install a drain is probably not that big of a deal as I am right next to the drain line for the A/C.
 
#12 ·
sorry mis-understanding. I mean up vertically, or out horizontally. We went horizontal with the kitchen (that is, up through the cabinet (from microhood), then horizontally out the side of the house. Like I said earlier, I would never exhaust my kitchen or bathroom into my attic.
 
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