1 Answer. Show activity on this post. You don’t provide much context to this question, but the short answer is there’s a maximum distance between the trap and the vent (should be specified by your local code). If the vent is too far away, the sink won’t drain well.Jan 14, 2013

Will a drain work without a vent?

Without venting, the negative pressure caused by the flow of draining water can potentially suck water out of the drain trap and allow sewer gases to enter the home. The vents allow air into the drain pipes to help keep the drain flowing properly.

Does a plumbing vent have to be straight?





Plumbing vents need to be straight on the vertical. This is necessary to avoid any vapor locks from occurring. When there is a bend in the vent pipe, moisture accumulates and is trapped.

Can sink drain be moved?

Moving the sink is almost always possible. The only problem with moving it is how the sink drain is vented. A drain must have a vent so that the water can move freely. Moving the drain and/or the water is very simple in most cases.

What happens if you don’t vent a shower drain?

Poorly-vented drain lines will not be able to effectively move wastewater and solid waste out of your building. This could lead to problems such as overflowing drains, backed-up toilets, and similar plumbing issues.

Can a plumbing vent run horizontal?

2. Can Vent Pipes be Horizontal? There is no problem with running your vent pipes horizontally as long as you remember that there should be a minimum clearance of 6 inches above the spill line.

Do plumbing vents have to go through the roof?





It does not have to go through the roof. From the plumbing code (I have the 2003 edition), P3103: It must not be less than 4 feet directly beneath a door, openable window or other air intake of the building or adjacent building.

Does shower drain need its own vent?

It’s easy to forget, but it’s a vital and required part of any plumbing fixture drain. The vent pipes remove sewer gases while allowing air into the system to help the water drain. Without a vent, your shower won’t drain correctly.

Will a shower drain without a vent?

Every plumbing fixture in your house needs to connect to a plumbing vent pipe. If it doesn’t, the fixture’s drain will not function correctly, which may lead to a dangerous situation in your house.

Does every drain need a vent pipe?

Without getting too far into building science, a general plumbing rule of thumb is that every drain needs a trap, and every trap needs a vent. All those traps and drains are designed to prevent sewer gas from entering your home.

Can a toilet and sink share a vent?



Wet venting is most common in conjunction with toilets and sinks; the drain for the sink is also the vent for the toilet. It can also be used for a variety of other applications but due to the following rules this is the most convenient and common situation to run into.

Does vent go before or after trap?

The simple answer is if your trap from the fixture cannot see the vent then it is installed wrong. We must always keep the vent connection above the trap weir to prevent siphoning and keep proper pressures on both side of the trap.

Where should a plumbing vent be located?

Vent pipes must be installed so they stay dry. This means that they should emerge from the top of the drainpipe, either straight vertically or at no less than a 45-degree angle from horizontal, so that water cannot back up into them.

How do you move a vent pipe?



Sever the existing vent stack from its branch fitting with a hacksaw or reciprocal saw; cut the pipe as near to the fitting as possible. Cut the pipe into sections to remove it from the wall or pull it out of the wall from the building’s roof.

How far away can a vent be from a sink?

Install the vent between the sink P-trap and the point where the waste line leading from the trap drops to the main sewer. If the waste line has a diameter of 1 1/4 inches, the vent can be no farther than 2 1/2 feet from the trap. If the waste line is 1 1/2 inches, this critical distance is 3 1/2 feet.

Can you offset a vent stack?

For this system to function effectively there cannot be any offsets in the waste stack portion. Once the highest branch interval is connected to the stack, the vent portion may contain offsets, provided such offsets are at least 6 inches above the branch interval connection.

How far can a drain be from a vent stack?

For a 1- 1/2-inc pipe the vent must be 42 inches away at the most while a 2-inch pipeline must have an optimum distance of 5 feet. For pipelines that have a diameter of 3 inches the range is 6 feet and for a 4-inch pipe the most it should be far from the vent is 10 feet.

Can two drains share a vent?



Common vent

This very simple concept allows two traps to be vented by the same vent. The two traps and their fixture drains can be either at the same level or at different levels, provided that they are on the same floor. The following diagrams show some of the various approaches to common venting.