Venting a small bath with AAV - is that ok?

Users who are viewing this thread

Robert Perkins

New Member
Messages
1
Reaction score
0
Points
1
Location
North Carolina
I am finishing out a basement which has the drain lines for a bath, toilet, and lavatory installed, stubbed up through the slab. The drain line runs under the slab, presumably, to a sewage sump about 25 ft away. Above the sump are a drain line connecting with the main drain to the street sewer piping, and a vent which goes through the roof. I assume the drains from the lav and bath connect to the toilet drain and continue to the sump in one pipe. The layout is a typical 5' x 8' bath, with lav, toilet, and bath all on one wall.

Questions:
1. I assume I need a sewage ejector pump instead of a standard sump pump? Is 1/2 hp sufficient? Any recommended brands?
2. One of the plumbers mentioned putting a Studor valve (air admittance valve?) in the small bath. Does that mean he doesn't intend to run a vent through the engineered floor joists above to connect to the sump vent? Is an AAV sufficient for a small bath with just the three fixtures, or possibly a bar sink on the other side of the bath wall?
3. If venting to the roof is really required, is there a slope required in the horizontal run (I assume the bath side would be lower?), and can it be connected to the vent above the sump?

Thanks for your replies. I noticed in a similar thread that the replies were well thought out and answered.
 

Jadnashua

Retired Defense Industry Engineer xxx
Messages
32,771
Reaction score
1,191
Points
113
Location
New England
I'm assuming (this can be dangerous!) that nothing currently drains into your tank now? WHere exactly does the main sewage line exit the house? That sump basin could just be for ground water, and have nothing to do with the existing stubouts in the bathroom. To tell, take the cap off of one of the drain lines and pour some water down it while someone else is looking in the sump. See if the water actually drains there.

If they did install the pit, and it is only intended for that basement bathroom, then yes, you'll need a pump for it. The size somewhat depends on how far it must lift the waste to get to the main sewer line. Not real familiar with them, and no, it needs to be a pump designed to pump sewage , not a sump pump which is designed to pump groundwater.

Assuming (again, dangerous) that they installed the ejector pit and it has a vent line, and it is ONLY used by the basement bath, you could run your bathroom vents to this one at least 42" above the floor, or 6" above the highest flood plane in that bathroom over to the vent from the pit. This is much preferred to using an AAV. IN some places, they are not allowed, and since it is mechanical, the gasket seal in it will eventually fail...hard pipe is better.

SO, too many questions on what's actually there to say for sure.
 

Cacher_Chick

Test, Don't Guess!
Messages
5,458
Reaction score
213
Points
63
Location
Land of Cheese
A sewage basin will be set up for a 2" discharge and a 2" vent. The basin is subjected to positive pressure and cannot be vented through an AAV. In addition, the plumbing fixture traps must be vented, and how that is done will depend on the layout of the drain lines. There is nothing to say that the vent for the basin and the fixture vents cannot be tied together into one vent through the roof.
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks