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-   -   Can bathroom exhaust and dryer share same outside duct? (http://www.diychatroom.com/f17/can-bathroom-exhaust-dryer-share-same-outside-duct-80221/)

benze 09-01-2010 11:30 AM

Can bathroom exhaust and dryer share same outside duct?
 
Hi,

I have a dryer sharing the same wall as my basement bathroom that exhausts directly to the outside through the foundation wall using a 4" duct. Pipe run is about 8'. My bathroom, however, doesn't have a ceiling fan, so it accumulates a lot of moisture.

Can I tee off the dryer line and connect a bathroom exhaust pipe to the same line to avoid having 2 outlets 2 feet from each other on the outside? I would put in backflow preventers on both lines to avoid the dryer from pumping air into the shower, and vice versa.

If it is not recommended b/c it is a 4" outside duct, if I were to increase that to 5", would it be acceptable? Or must the exahust lines for bathroom fan and dryer be separate? Is there any code restrictions on this?

I live in Montreal, Quebec, Canada, if that makes any difference (code wise or other).

Thanks!

Eric

fabrk8r 09-01-2010 12:03 PM

Bath exhaust should always be separate from any other duct, as should dryer vents.

All the code books I've ever seen say that too.

The reason it's not a safe thing to do is because of both sanitation issues and fire safety issues.

spaceman spif 09-01-2010 01:01 PM

Plus if your backflow prevent ever failed, your clothes would come out smelling like crap. :)

NitroNate 09-01-2010 01:32 PM

don't bathroom exhaust vents vent through the roof, while dryer vents vent out the wall on the side? at least that is how my house is set up. all my bathroom vents run up through the attic and out the roof.

Rambo 09-01-2010 01:49 PM

Quote:

Originally Posted by benze (Post 494213)
Hi,

I have a dryer sharing the same wall as my basement bathroom that exhausts directly to the outside through the foundation wall using a 4" duct. Pipe run is about 8'. My bathroom, however, doesn't have a ceiling fan, so it accumulates a lot of moisture.

Can I tee off the dryer line and connect a bathroom exhaust pipe to the same line to avoid having 2 outlets 2 feet from each other on the outside? I would put in backflow preventers on both lines to avoid the dryer from pumping air into the shower, and vice versa.

If it is not recommended b/c it is a 4" outside duct, if I were to increase that to 5", would it be acceptable? Or must the exahust lines for bathroom fan and dryer be separate? Is there any code restrictions on this?

I live in Montreal, Quebec, Canada, if that makes any difference (code wise or other).

Thanks!

Eric


thats a big fat NEGATIVE.....

bernieb 09-01-2010 02:45 PM

I've seen an awful lot of bathroom exhast fans just exit into the ceiling proper, between ceiling /floor joists.

beenthere 09-01-2010 06:58 PM

Code prohibits them sharing the same duct. Or vent hood.

Marty S. 09-01-2010 06:59 PM

Quote:

Originally Posted by NitroNate (Post 494270)
don't bathroom exhaust vents vent through the roof, while dryer vents vent out the wall on the side? at least that is how my house is set up. all my bathroom vents run up through the attic and out the roof.

Depends on the house lay out. I wouldn't run basement bath fans out the roof or first floor bath vents on a two story house. My slab on grade house has the laundry area on an interior section so out the roof with the drier vent is the only option.

Scuba_Dave 09-01-2010 07:18 PM

Quote:

Originally Posted by bernieb (Post 494308)
I've seen an awful lot of bathroom exhast fans just exit into the ceiling proper, between ceiling /floor joists.

Which does not meet code & a good way to cause mold if there is a shower in the bathroom

benze 09-07-2010 06:04 PM

Quote:

Originally Posted by Scuba_Dave (Post 494480)
Which does not meet code & a good way to cause mold if there is a shower in the bathjoom

How bad is it to vent a powder-room exhaust straight into the attic? Am living in Montreal, Quebec, Canada, so I am concerned about condensation in winter months; when ventillation being evacuated from the powder room is warm coming into contact with the cold air in the attic.

Do I have to worry about that? Putting in a roof vent would be quite ugly as this powder room is in the front of the house, the vent would be quite visible from the front door.

Thanks,

Eric

Scuba_Dave 09-07-2010 06:07 PM

Venting warm air into the attic in the winter is not a good idea
Every code I have seen people refer to indicates exhaust MUST exit the building

beenthere 09-07-2010 06:22 PM

Quote:

Originally Posted by benze (Post 497391)
How bad is it to vent a powder-room exhaust straight into the attic? Am living in Montreal, Quebec, Canada, so I am concerned about condensation in winter months; when ventillation being evacuated from the powder room is warm coming into contact with the cold air in the attic.

Do I have to worry about that? Putting in a roof vent would be quite ugly as this powder room is in the front of the house, the vent would be quite visible from the front door.

Thanks,

Eric

You'll end up with lots of condensate in the attic, and soak your insulation, and grow mold.

hvaclover 09-07-2010 06:23 PM

LOLOLOLOL...this thread has me rolling on the floor!!!

I have a neighbor who vented a basement bathroom into a 4" tee off his water heater flue pipe. Been like that for twenty years. The guy's wife and mine are best friends. i don't hang with the guy but take care of his ac.
I was there this summer and he still has the bathroom fan duct going to the water heater flue.:laughing:

Some people never listen

benze 09-08-2010 09:41 AM

Quote:

Originally Posted by beenthere (Post 497407)
You'll end up with lots of condensate in the attic, and soak your insulation, and grow mold.

That's pretty much what I had figured too, but was kinda hoping someone would tell me otherwise.

Another option I have is to exhaust it over my front porch. I have a large overhang in front (about 1-2 feet high and about 5 feet deep) that has no insulation and soffit venting. I could just tie the end of the duct work so that it exhausts in that space, but I am concerned about ice buildup in a space that wasn't designed for it.

I'm sure that it is a terrible option too, but just on the chance that it might not be as bad as I think, I'm hoping to get some feedback....

Thanks,

Eric

fabrk8r 09-08-2010 09:52 AM

Exhaust it outside through an appropriate vent hood. Do not terminate the exhaust inside the structure, anywhere, at all. All the reasons why it isn't a good idea to terminate bathroom exhaust inside the structure have been discussed in previous posts.


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