Looking for some help on venting

[rmachetto]

Hello:
I'm an electrical design person looking to find out
the hook-ups differences between dry, wet & circuit
venting. I familiar with "dfu" requirements. The local
code enforcement web-site does not explain it clearly
enough.

 

[PEDARRIN2]

Dry venting is the typical venting where the vent is connected directly to the trap arm coming from the fixture. It is called "dry" because it should never see any liquids from the drainage of the fixture.

Wet venting is a catch all phrase for several types of venting. Circuit venting is one of them. Basically it is used when dry venting is not feasible for whatever reason. Typically, the drain pipe is sized larger to provide for additional area in the pipe for air flow. Plumbing is typically not full flow anyway, but with wet venting, additional area is designed for the air flow in the pipe.

Circuit venting is fairly well described by code publications. It is typically for only fixtures which connect in the horizontal plane (floor drains, floor mounted toilets, etc.) You basically put a vent between the two upstream fixtures and connect to a "dry vent" downstream of the connection. You can only put up to eight fixtures on a circuit vent before you have to add another one.

You have to be careful about using wet venting. Some code authorities do not allow it or circumscribe its use extensively. If you are in a jurisdiction that uses the UPC, then this is the case. The IPC allows use of wet venting. Determine what code you have to follow. That will tell you if you can do it.