Proper Venting for Plumbing Systems - What You Need to Know

Proper Venting for Plumbing Systems: What You Need to Know

If you’re planning to remodel your kitchen or your bathroom, you will surely have to deal with the plumbing tasks that come with it. Among these involve plumbing vent systems, which are usually more difficult to handle.

The purpose of vents in plumbing is to allow waste water to be smoothly flushed down the sewer system or the septic tank and prevent harmful gases from entering the home. If vents are not installed properly, your home will stink of sewage gas.

So if you’re planning to renovate your home, ensure that your pipes are properly ventilated, especially if you are going to get a new set of fixtures like sinks, tubs, or toilets.

Types of Vents

How many vents do you need for your plumbing system? Each fixture will have a vent that will be connected to the main vent or the vent stack. Depending on where your fixtures are located and how close they are to the main stack, the vent attached to them will have a different name.

1. True Vent

If your sink, tub, or toilet is close to the vent stack, the ventilation for it will be coming from the true vent. The true vent is a vertical pipe attached to the drain line and the main vent. Air pushes down from the main vent and directly through the true vent. If your fixture is located far from the vent stack, it will be connected through a different vent.

2. Revent Pipe

A revent pipe is a horizontal pipe that is attached directly behind the fixture to the drain line and the main vent. Also called “auxiliary pipes,” revent pipes are what connect fixtures that are a little far from the main vent.

3. Common Vent

When you have fixtures on opposite sides of your wall, your fixtures will have a common vent. The common vent ties the two drain lines together in what is called a “sanitary cross.”

4. Wet Vent

If your sink, tub, or toilet is close enough to the stack, code might allow for them to be connected to the main vent through a wet vent. A wet vent is a drain pipe that also functions as a vent. Water passes through it, hence its name.

5. Loop Vent

If your fixture is not up against a wall like a kitchen island, it will be attached to a loop vent. It’s called a loop vent because it loops around other pipes or fixtures to connect to the main pipe.

Introducing the Air Admittance Valve (AAV)

A great new device, and to some localities, a great new alternative to the plumbing vent system involves a one-way valve that is in line with air venting for plumbing – the Air Admittance Valves.

AAVs allow air to enter as waste drains, and it seals back up through the force of gravity before any sewage gases enter back into the building. AAVs work without a vent. They are also used to prevent slow draining and gurgling.

Because the AAV is relatively new, make sure to know about your area’s code before purchasing any.

Identifying the Critical Distance

The amount of space between the fixture and the vent pipe is known as the critical distance, and it usually involves complicated calculations with formulas that vary for each locale.

The critical distance is identified using three factors: what the size of the pipe used for the plumbing vent (as required by codes), the kind of fixture to be installed, and how many fixtures are wet vented on similar lines. The calculations require careful measurement of the pipe length. After which, it is highly recommended that you consult with a plumbing inspector for the possibility of wet venting, some tips on proper ventilation, and identification of which plumbing vent systems works best with the local code.

Some Points on the Main Drain

Planning out your drain lines helps to minimize the risk of clogging when you install your vents. Although kitchen sink drainpipes (1-1/2 inches) and bathroom sink drainpipes (1-1/4 inches) appear smaller compared to the rest of your drain system, they lead to larger branch drains pipes, which continues into a 4-inch stack.

Since the main stack is positioned vertically, it rarely clogs. The pipes connecting the stack need to be positioned horizontally to allow water to flow through them freely. Since the main drain line is found underground, it’s best to call for plumbing experts to check your plumbing system’s main drain line for any clogging.

That said, to ensure safety when implementing processes involving plumbing vent system, make sure to always check with plumbing experts for guaranteed professional care. At A Better Plumber (ABP), we have the best plumbers at Arvada, CO, who can help you implement proper venting for your plumbing systems. For inquiries and more information, call us now!

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