What is a combination drain and vent system?

Combination Waste and Vent System. A specially designed system of waste piping embodying the horizontal wet venting of one or more sinks or floor drains by means of a common waste and vent pipe adequately sized to provide free movement of air above the flow line of the drain.

What types of fixtures can be served by a combination waste and vent system?

A combination waste and vent system shall only serve floor drains, sinks, lavatories and drinking fountains. A combination waste and vent system shall be considered to be the vent for those fixtures.

What is the difference between a drain pipe and a vent pipe?

Drainage pipes carry waste out of your home to either the city sewer or a septic tank. Vent pipes supply fresh air to each plumbing fixture in the house, which helps the system move water through the drainage pipes each time a toilet is flushed or a sink is drained.

Can a vent pipe also be a drain pipe?

A true vent pipe must remain dry while water runs down the drain. A wet vent also serves as a drain line but is large enough that it never actually fills with water. In some cases, local codes allow for other venting strategies.

Does every plumbing fixture need a vent?

Every plumbing fixture must also have an attached vent. Without a vent, negative pressure from water leaving the system can cause a siphon which empties the trap. The top of stacks must be vented too, via a stack vent, which is sometimes called a stink pipe.

Combination Waste

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.

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.

How many vent pipes should a house have?

At least one main vent stack is required for every building that has plumbing when connecting separately to the sewer for the building or its septic tank. The stack has to run the most direct route through open air or be ventilated to extend to open air.

What happens if you don't vent a toilet?

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 sink drain be connected to a vent pipe?

Tying Into a Vent Stack

Individual vents must rise above the overflow line of the topmost plumbing fixture in the house before you can tie it to the main vent stack. This is a precaution that prevents the vent from becoming a drain if that fixture's drain gets blocked.

Do all toilets need a vent pipe?

“Does a toilet need a vent?” And the answer is yes, your toilet has to have a vent. For more information on the great importance of plumbing vents, read our plumbing vent article here. And the size of this vent pipe depends on your local plumbing code.

Do shower drains need to be vented?

Vent Pipe Requirements for Showers

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.

How do you get sewer smell out of vent pipe?

While you can't stop the creation of septic and sewer gases, you can eliminate the odor that is caused as they exit the roof vent pipe or septic tank vent by installing a Wolverine Brand® carbon filter on top of your sewer vent.

How does a combination waste vent work?

Combination Waste and Vent System. A specially designed system of waste piping embodying the horizontal wet venting of one or more sinks or floor drains by means of a common waste and vent pipe adequately sized to provide free movement of air above the flow line of the drain.

Can a washer and shower share the same drain?

You can tie in a shower and tub drain to your washing machine drain as long as there is a vented pipe tied into the drain to keep the flow moving along fluidly.

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.

How do you vent a bathroom with no outside access?

Installing a ceiling vent is probably the most efficient way to ventilate a bathroom with no outside access. A ceiling vent is a unique machine that allows air to escape from the bathroom. In other words, it's a machine that, like an open window, allows moisture to escape from your bathroom.

Can two toilets share the same vent?

Most houses have more than one toilet, and if they are on the same side of the house, their waste lines can usually tie into the same stack. If they are on opposite sides, however, each may need its own stack. Since the stacks must be vented, this would mean two vent openings on the roof.

How far can a vent be from a toilet?

According to the UPC, the distance between your trap and the vent should be no more than 6 feet. In other words, for the vent to work properly, it needs to feed into the drain line within 6 feet of the trapways that connect to it.

How high above the roof should a vent pipe be?

Unless a roof is to be used for any purpose other than weather protection, extensions of vent pipes through a roof should be terminated at least 12 inches above the roof. The vent should be extended at least seven feet above the roof if it is to be used for something other than weather protection.

How far can a vent pipe be from the drain?

For a 1 ½-inc pipe the vent should be 42 inches away at the most while a 2-inch pipe must have a maximum distance of 5 feet. For pipes that have a diameter of 3 inches the distance is 6 feet and for a 4-inch pipe the most it should be away from the vent is 10 feet.

What is the difference between a stack vent and a vent stack?

A vent stack is a vertical pipe that is only used for venting, and runs upward from the drain piping to the open air outside the home. Vent stacks are primary vents and accept connections from other vents in a plumbing system. A stack vent is used for both drainage and venting.

Does a washing machine drain line need to be vented?

All plumbing fixtures—including washing machines—must be vented. Improperly vented drains can be sluggish and noisy, and can emit hazardous fumes. Properly vented drains allow the P-trap to do its job: prevent sewer gases from escaping into your home.

Will a sink drain 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.

Can plumbing vents terminate in the attic?

Yes, a plumbing vent can terminate in the attic. But it must have an air admittance valve at the termination to keep noxious sewer gas fumes from rising into the attic.