Garage Utility Sink Plumbing Question

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Nate Schwartz, Aug 4, 2013.

  1. Nate Schwartz

    Nate Schwartz New Member

    Messages:
    2
    Location:
    Florida
    Hi all! I am looking to install a utility sink in my garage on a wall opposite a bathroom sink. As luck would have it a house is being built in my neighborhood that is the same model as mine so I was able to take some pictures of the in wall plumbing where I am hoping I can tie in.

    plumb1.jpg
    This is the garage side of the wall and shows hot and cold water and the drain pipe. To be honest I do not know what that smaller pipe in the lower right corner is. The same sink in my home does not have that particular pipe, but a seperate sink in the same bathroom does and it is connected to an Aqua-Gard Thermostatic Mixing Valve. I don't really understand why it is needed and why only on this one sink either so maybe someone can explain that to me as well.

    plumb2.jpg
    This is the same pipes from the bathroom side of things.

    My questions essentially is, can I tie in to these pipes for my garage utility sink? From what I have read and researched so far, tying into the hot and cold water shouldn't be an issue, but the drain/venting might be. The vent in particular confuses me since I do not see where or how it is vented at all. In the roughed in house I can see the vent stacks going up but I don't see this sink tying into it anywhere. The other sink in the same bathroom is vented with an AAV but the two sinks are on different walls so I don't see how they could be sharing that. Can anyone explain to me how I can do this if it is even possible? My though was to tie the hot, cold, and drain pipes for the utility sink and bathroom sink together and then just put an AAV in the garage to vent the utility sink. Please let me know if any of this makes sense or if I am completely off on all of it. Thanks so much!

    Nate
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,056
    Location:
    Cave Creek, Arizona
    That sink, unless it has an AAV in the cabinet is not, nor can it be, vented. From your pictures, I do not have a very high estimation of the "plumber" who installed it. Depending on where the water heater is, that third pipe could be a connection for a hot water circulation system.
  3. Nate Schwartz

    Nate Schwartz New Member

    Messages:
    2
    Location:
    Florida
    HJ,

    So I decided to go ahead and open my own wall to see what was there. What I found was essentially the same as the pictures above except the drain pipe did in fact continue up which I assume is then attached to the vent stack. Is it acceptable to simply add a wye below the bathroom sink drain and drain my utility sink there?
  4. Terry

    Terry Administrator Staff Member

    Messages:
    15,303
    Location:
    Bothell, Washington
    If you are cutting in a fitting for a sink on the vertical, it would be a santee.
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