Plumbing vents

[kpierce]

Came across something new today. Combined plumbing vents (not stacked). Code check says "two or more" may be combined as long as they maintain 1/4 in. per foot rise. Is there a max number of vents that should be combined? Also, what about max length on the branch? I assume as long as the rise ratio was maintained it wouldn't max out.

[Gary Farnsworth]

Ask your local code inspector. We do not quote codes.

[kpierce]

You wouldn't write up combined plumbing vents that had a negative/even grade on the branch?

[kpierce]

Originally Posted by gfarnsworth

Ask your local code inspector. We do not quote codes.

Have you ever read this message board? There's lots of guys who love to quote code.

[Gary Farnsworth]

Then, read the code check, or ask the Blue Man Group.

[Christopher Currins]

Is this what your talking about?

When fixtures are connected to one horizontal branch through a double wye, a sanitary cross in a vertical position, or a manufactured fixture carrier, a common vent for each 2 fixtures back-to-back shall be provided. (See Appendix K: Illustration BB.)

Section 890.ILLUSTRATION BB Fixtures Back-to-Back in Battery

(Referenced in Section 890.1520(d))

[Gary Farnsworth]

That is an exact Blue Man Group PVC instrument blue print.

[kpierce]

Essentially. However, one vent intersects perpendicularly. Basically, three bathrooms, one vent goes straight up and out, one comes up and over and connects to the first one mentioned. The third comes up, over and joins the second one perpendicularly.

[kpierce]

Originally Posted by gfarnsworth

Then, read the code check, or ask the Blue Man Group.

That legislation has made you one bitter man.

[Christopher Currins]

As long as they're sized properly I wouldn't see a problem. But, of course, I'm not a plumber.

[kpierce]

Originally Posted by ccurrins

As long as they're sized properly I wouldn't see a problem. But, of course, I'm not a plumber.

Yeah, for this setup, I was thinking as long as they had a proper rise and size, it wouldn't be a problem. Just got me thinking about max lengths and combinations and thought I'd post. Should have remembered that this MB is mostly filled with bitter old men with thorns up there asses cuz they aren't creative enough to diversify in a rough market.

[Christopher Currins]

I agree, there were about 50 members logged in when you posted the question and all you got was an answer from a non-member and a grumpy old one. Nothings changed.

[Nick Gromicko]

Came across something new today. Combined plumbing vents (not stacked). Code check says "two or more" may be combined as long as they maintain 1/4 in. per foot rise. Is there a max number of vents that should be combined? Also, what about max length on the branch? I assume as long as the rise ratio was maintained it wouldn't max out.

I believe you are describing a "circuit vent"...

Is there a max number of vents that should be combined

...in which case a maximum of 8 fixtures are permitted.

Also, what about max length on the branch?

The maximum length of the branch is dependent on the size of the trap (the bigger the trap the longer the distance to the vent can be).

The minimum required diameter of a branch or circuit vent is 1/2 the the drain served but at least 1-1/4 inches in diameter. And bigger in diameter if the vent is more than 40 feet long.

Code check says "two or more" may be combined as long as they maintain 1/4 in. per foot rise.

If you are talking about the slope of the drain... no. 1/8-inch per foot rise (slope) is fine for 3" and 4" traps.

[kpierce]

Originally Posted by ccurrins

I agree, there were about 50 members logged in when you posted the question and all you got was an answer from a non-member and a grumpy old one. Nothings changed.

No worries though. I didn't "need" to know an answer. Just thought a little dialogue on the subject would be interesting.

[kpierce]

Originally Posted by gromicko

I believe you are describing a "circuit vent" in which case a maximum of 8 fixtures are permitted. The maximum length of the branch is dependent on the size of the trap (the bigger the trap the longer the distance to the vent can be).

Thanks for the response, Nick.