Hello - I bought an older house and I am renovating and making my half bath a full bath. I wanted to install an exhaust fan in the bathroom, but it is not very convienent to send it to the side of the house and I don't won't to bother cutting a hole in the roof. So, I was wondering, since the main air vent to both bathrooms is directly above my new bathroom, can I have piece of PVC installed so that my exhaust vent blows into the air vent? Is this code worthy?
No. Except there's a water-trap, you can only connect draing piping to the outside, via drain line or vent. Sewer gas can be explosive, and it's happened that contractor cracks a gas main near a sewer line, with natural gas getting into house with dry trap. With house coming apart in a fireball.
This was a block away.
So you see why sewer venting is not a "convenience" thing.
Ok...I am no plumber and makes good sense, but is there enough pressure in the air vent to push the "sewer gases" sideways and down to my exhaust fan. I was thinking as long as I don't create a direct route I would be ok. I just wanted to tie on to the side, kind of like my sink is right now.
Thanks for the suggestions. I guess I will do a little more research.
The flex hose from mine is wired to the inside of one of the existing roof vents. It works fine. When I re-roof soon, I'm having it routed to its own vent, but you could get away with jury-rigging it, if necessary.
Cool...I am fixing this house to live in, but not very long (~5 years), so I wanna stay close to code so that people won't make me fix it when I go to sell the house.
Be sure to wire the pipe as far up in the vent as possible, so moisture is blown all the way out. Otherwise, it's possible to have condensation on the inside of the metal vent, which may drip back down again. I wondered about this with mine, so I've observed while the shower as on full blast. You should do the same when you're done.
Yea, that is why I thought the idea was a good one, b/c it is a very short distance, just up 1' and over 1' ft, but the air vent still has a way to go, so I thought if there was condensation, it is going to drain down the air stack and into the sewer.
I just want to make sure you guys don't think the sewer gas is going to make its way past my exhaust fan?
I sure hope you are talking about one of the attic vents and not the sewer vent, Joe. Sounds like Johnny wants to hook into the sewer vent pipe stack which will cause all sorts of trouble when he wants to sell the house. Not to mention that "wonderful" odor he'll be trying to track down in his bathroom on those occasional days.
My advice Johnny, is don't tap into the sewer vent stack unless you intend to use it to dump sewage into.
If you interconnected the bathroom vent to the DWV vent, and if the exhaust fan isn't running, why wouldn't it get past? It's a _gas_, remember?
Would just need a minor vacuum in the house (eg: woodstove or stove vent) to make it a high volume blast of stink.
You're not going to attach it to the sewer pipe or vent. I'm talking about the attic vents. If you don't have one nearby, it would really be worth your money to install a vent specifically made for the fan, or have a roofer do it.
Repeat: You are not going anywhere near the sewer pipe. Crush the idea.
Awesome...good ideas. Idea is dead. Makes sense. I thought I was onto to something, but as usual, there is a reason why it is not done this way.
I was just testing you guys....jk. have a whole house fan, and the minute I turn that sucker on, I can see it sucking the air from my bathroom including the air in my exchaut fan vent when the fan is not running.
Back to the drawing board. I appreciated every ones ideas and suggestions. Seems like a really dumb idea now that I look back.
That would be the exact reason, sink drains have traps to prevent sewer gas from entering the room.
The fan connection to the DWV vent pipe not only violates code(s), its a plain Bad Idea as stated by others. Aside from a low pressure conditon in the building (think kitchen exahust fan, opening a well sealed outside door with all the windows closed, the aforementioned fireplace or wood stove) causing sewer gas to be drawn in when the fan is not operating, it is possible (though less likely,) that with the bathroom fan operating, it is conceivable that the positive pressure introduced by the fan could have an adverse affect on one of the drain trap's contents, should the vent outlet become (partially or fully) obstructed, say be snow. I admit, this is a long shot, but you are looking for reasons why this is a Bad Idea, that's another.
I'll echo what a previous poster said - make sure the fan exhaust makes it outside. Don't let it loose inside the attic. You'll be asking for moisture trouble.
Here's something to think about. Know why managers of large commercial buildings have ALL the floors mopped routinely -- even in areas that are never used? It's to keep the floor drains wet so they don't stink (seriously). They also make floor drains with "drippers" built in that connect to a water line. They drip to keep the trap wet.
I guess all I can add to this is to cut the pipe open, take a good whiff, and see what you think.
BTW, what you are proposing is known to happen in larger applications, but they use a mechanically ventilated pipe so there's no back draft.
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