Drain for new utility sink in garage


  #1  
Old 07-11-14, 09:21 AM
O
Member
Thread Starter
Join Date: May 2014
Posts: 4
Received 0 Votes on 0 Posts
Drain for new utility sink in garage

Hi. I'm new here! It seems like there is a lot of knowledge and experience here and I'm hoping to be able to learn something from you all.

First some background.

Last year, I had my water heater in my garage replaced with a tankless unit. I am installing a sink where the old water heater used to be. I asked the plumbers who did the water heater to add a valve where I could attach the sink, and they did. All of this has already passed inspection.

Now, I am getting around to installing the sink. My question is about the drain. around the drain for this sink. There is no vent stack that I can use, so I am using an AAV, I called the inspections department of the town I live in and they confirmed that AAVs are accepted where I live (NC).

The attached pictures show what I've done.

As you can see, the water lines going to and from the water heater as well as the gas line are somewhat in the way, so I have to work around them which makes things a bit awkward. I'm hoping that you guys could critique this before I glue it together, or if there's something I should have done differently?

Starting from the wall, it goes like this:

1. Cleanout on the horizontal run - not 100% sure it's requried but it certainly can't hurt, right?
2. 45 degree elbow
3. 6" pipe at an angle
4. 60 degree elbow (had to use the 45 plus 60 to result in a vertical pipe from the odd angles
5. Sanitary Tee mounted vertically, which connects to horizontal drain arm, P-trap, tailpiece, and sink with slip fittings)
Everything beyond here is for connecting the vent:
6. 90 degree elbow
7. 6" horizontal pipe
8. 90 degree elbow
9. 6" vertical pipe
10. Studor AAV

First, what do you think? Does this look good enough? It seems a bit unwieldy but I can't think of a better way to do this. Basically, would this probably meet code requirements?

Rules state the AAV must be 4 inches above the trap arm. How is this 4 inches measured? Top of arm to bottom of AAV? Top of arm to top of threaded fitting where the AAV attaches?

I made the most restrictive assumption, that it means top of arm to bottom of the threaded fitting. Therefore, in order to get and exceed the required 4 inches and still leave room to unscrew the AAV, I had to use 2 90 degree elbows connected by a horizontal pipe to get out from under the sink. I am uncertain however if the 90 degree elbows and horizontal pipe between the Sanitary Tee and the AAV are acceptable. The pictures I can find online of AAV installations don't have any horizontal runs like this but my situation seems to be a bit unusual.

Also, does this whole setup needs to be supported by a strap? I could conceivably attach a strap to the horizontal pipe at #7 and secure it to the underside of the sink.

The final question I have is, since this is in a garage, how much of this needs to be insulated? Is it only between the trap and the wall, or does everything up to the AAV need to be insulated as well?
 
Attached Images    

Last edited by orulz; 07-11-14 at 10:34 AM.
  #2  
Old 07-14-14, 10:09 AM
O
Member
Thread Starter
Join Date: May 2014
Posts: 4
Received 0 Votes on 0 Posts
I think my previous post was too wordy. I don't blame people for not reading it, so, this time I'll make it short. Please find pictures below...

1. Code specifies a minimum 4 inch rise from trap arm to AAV. How is this measured?

2. Can there be a horizontal run between the sanitary tee where the trap arm connects and the AAV? In my case this horizontal run would be ~6 inches long, and would be dry unless the drain backs up.

3. Since this is in a garage, how much of the drain pipe should be insulated? Just the "Wet" part, or the whole thing?
 
  #3  
Old 07-18-14, 09:59 AM
Z
Forum Topic Moderator
Join Date: Sep 2005
Location: USA
Posts: 5,817
Received 203 Votes on 181 Posts
Hey there, sorry for the delayed response... sometimes it does take a while to get through longer posts.

I think your setup looks pretty good. Even though it may look funny with the trap crossed over like that, it certainly works and shouldn't cause you any issues.

To answer your questions:
1. Code specifies a minimum 4 inch rise from trap arm to AAV. How is this measured?
I'm pretty sure it's measured from the center-line of the trap arm pipe to the bottom vented portion of the AAV. But that said, the higher it is, the better, so in your case, I would extend it up to the rim of the sink or preferably even higher.

Can there be a horizontal run between the sanitary tee where the trap arm connects and the AAV? In my case this horizontal run would be ~6 inches long, and would be dry unless the drain backs up.
No, there shouldn't be any horizontal run until the vent reaches 18" above the flood rim of the sink. But, there is a caveat in the code that states that you can run a horizontal run if needed to avoid obstacles, typically a kitchen window or medicine cabinet. The final decision would be up to your local inspector, but in my book, it would be fine the way you have it.

Since this is in a garage, how much of the drain pipe should be insulated? Just the "Wet" part, or the whole thing?
You can insulate the trap, which is the only part that will have water in it. But insulation will only help for a short period of time. If you use the sink at 5pm, and it's freezing overnight in the garage, the water inside the trap will freeze, regardless how much insulation you add. It will just keep the water warm for longer.
In NC you probably don't have many freezing nights, and rarely any really cold nights, so you might be fine. What are you doing with the supply pipes? I see they are insulated, but is the garage heated a bit, or are you using heat tape?


I would add some kind of support near the AAV to hold the whole structure up. Also, did you use primer on the PVC? Most locales require purple primer so it's clear that the pipes have been prepped.

-Mike
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: