Hi, I'm hoping it is not too long to ask a question on this thread. I am in the process of trying to plumb a DWV system for a cabin in the country. Your solution to Rick's question is close to some questions I have but it is hard to tell exactly how the drains run in your diagram. This cabin has a 3/4" plywood floor on 2x4 joists on 4x4 beams which sit on cinder blocks so that the floor is approximently 12" off the ground which does not leave a lot of room to work. I have a 3" vertical stack in the bathroom going through the roof. The bathroom sink trap arm is 2.5' long and will drain & vent directly into the stack. Just below the floor I have a 3x3 sanitary T vertically placed at the bottom of the stack and the 3x4" closet bend drains nicely into it at an excellent grade. Below the vertical sanitary T I currently have a 3" 90 degree which turns the vertical stack into a horizontal drain without having to dig under the house. Not only is the dirt very hard without a lot of clearance to dig but I don't like the idea of a lot of digging there for fear of undermining the blocks which support the house. After the el I have a 3 x 2 wye to drain the shower via a 4' trap arm followed by another 3 x 2 wye to drain another 2" horizontal drain coming from the kitchen. Then the main line increases to 4" and a 90 degree bend to transition the drain out the back of the house at the proper grade where it will head towards a septic system.

I think the toilet and bathroom sink should be adequetly vented by the vertical stack but I need to provide venting for the shower and kitchen lines. The kitchen sink itself will be vented by an AAV with its drain dropping vertically through the floor into a 2" horizontal drain which is about 10-12 feet from the 3 x 2 wye mentioned above so that drain line will also likely need vented. I can easily get another 2" vertical vent to run up the inside of the wall and re-vent into the main stack. Coming off the shower trap arm I could put in a 2 x 2 wye to connect the shower trap to the 2" vent.

My questions are on venting and clean outs
1. do the wye's (TY) have to be facing straight up or can they be put on the horizontal drains where the outlet runs parallel to or at a 45 degree rotation on the drain line?
2. can the wye (ty) vent on the shower trap arm feed a regular 't' on which the kitchen line can also vent?
3. when using a wye for a vent do you have to also use a 45 degree froming a TY?
4. can vent lines run horizontal underneath the house then transition into a vertical vent going through the roof or re-venting into the stack? If yes, how much above the horizontal drains should horizontal vent line be?
5. does the 10-12' horizontal drain from the kitchen need another vent before draining into the main line if the sink trap itself is vented with the AAV?
6. can I put a clean out at the bottom of the vertical stack below where the bathroom sink drains/vents to satisfy needing to clean out the horizontal drain under the house?
7. would the 10-12' kitchen line have to have another cleanout or could it just be cleaned out by removing the p-trap?

I'm asking these questions because the excellent amount of information I have found on the internet of drain systems really does not discuss in depth the orientation of WYEs and Sanitary T's on horizontal drain lines. But I did notice above the info about a sanitary T as a vent take-off on a horizontal line must be rolled up 45 degrees. This is the type of info I am looking for as I do not have very much space to work with and need to vent the lines mentioned and want to provide cleanouts for ease of future cleaning but again do not have much space to work with. Any information you could share which may help with plumbing in tight spaces would be greatly appreciated. - James

Hi James...

We'll see if we can get this moved to its own thread. Meanwhile... ;)

Not to insult anyone, OK? but let's start by defining fittings? A wye fitting is shaped like a wye (1st image). A sanitary tee is shaped like a tee fitting (2nd image). A combination wye and 1/8th bend look like a really long sweep tee fitting (3rd image). A dandy cleanout (also called a test tee) looks like my last image.

Wyes and combination wye and 1/8th bends are for connecting horizontal drain lines into main lines. Wyes can also be used for vents, but most of the time we use sanitary tees. Sanitary tees can be used for drains off a vertical stack and can also be used on the horizontal to pick up vents.

Now, to answer your questions:... ;)

1) Sanitary tees can look straight up or they can be set at a 45 degree angle for venting purposes. Basically, the fitting needs to roll above the center of the drain line is all.

2) No need to add vent to the kitchen sink drain line as long as you are adding an AAV under the sink... even if it is 10-12' until it connects into the main drain line. While piping under the sink add a full-size dandy clean out or use a union type ptrap which has a full-size cleanout and you should be all set with the kitchen sink and the kitchen sink cleanout.

3) When using a snaitary tee fitting for a vent you can use 90s, 45s, 22.5 degree fittings... as long as the sanitary tee fitting is above the center line of the drain line.

4) Horizontal vents need to pitch back toward the drain line. If you are tight for space then you can make the vent almost level, but be sure to have some pitch.

5) No.. see #2

6) Sure can putting a dandy cleanout on the vertical under the vanity works well... same for the kitchen sink... right?

7) See #2

Remember to hang all pipes every 3-4 feet maximum... even the vents, and pitch all pipes at 1/4" pitch per foot if you can.

Back to you...

MARK

Mark,
Thanks so much for your time and the valuable information. I think there should be ample space to implement the system without too many headaches.

James

Good news.

Pop on back if you have any more questions...

MARK