Re: venting problem
Posted by Parker on October 23, 19100 at 10:14:49:
In response to Re: venting problem
Thanks for the explanation. I can see three types of stoppages:

1) A stoppage between the kitchen sink and its vent/drain connection. This would not be a problem since no waste could get through to the vent.

2) A stoppage far downstream -- under the house and beyond the point at which I'm connecting the new utility sink drain. In this case, it seems as though all lower fixtures become drains as waste backs up and exits through sinks, etc.

3) A stoppage between the kitchen sink vent/drain connection and the new utility sink drain. This seems to be the situation you're describing. In this case, the new vent would become a drain, but wouldn't the waste simply run down the vent and on through the new utility sink drain? If I DIDN'T install the new vent, the kitchen sink would overflow onto the kitchen floor.

I'm sure I'm exposing my ignorance, but I don't see that installing the vent 2" lower than the flood level of the kitchen sink creates any problems I didn't already have. Am I missing something?

: If you connect below the flood level of the fixture, the vent would become a drain line in the event of a drain stoppage, when the sink filled to the level of the lower vent.

: : I'm adding a utility sink in my garage. To vent the drain, I'd like to connect into the vent pipe running up vertically from the kitchen sink drain pipe.

: : I've heard that I need to connect into the vent at least 6" above the flood level of the sink. Why is this minimum height required? I can easily tap into the vent pipe behind the dishwasher, but that means I will connect to the vent pipe about 2" below the flood level of the sink. Connecting any higher would require heavy drilling and tearing into visible portions of the kitchen wall.

: : How big of a risk would I be taking if I connected it lower than the 6" requirement? If that's unacceptable, any other suggestions? Thanks in advance.

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