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Do Plumbing Vents Need Caps? (Read This First)

do plumbing vents need caps

Many homeowners believe they need caps on their plumbing vents. They assume that adding this cap to the top is the best way to help keep everything safe and can prevent anything from getting into the plumbing system. However, these caps placed on top of the plumbing vents can actually backfire and cause more issues than it is worth. 

It is generally best not to add caps to your plumbing vents. Adding these can mess with the natural way these vents are meant to work in your home, causing issues with the amount of water or the pressure in the system. It is best to keep this open unless your plumbing specialist suggest otherwise for some reason. 

Let’s take a look at what the cap is for a plumbing vent and some of the reasons why you may want to consider not having one on your plumbing vents. 

Do I Need a Cap on My Plumbing Vent?

Many people assume that you need to have a cap on your plumbing vent for it to work. However, there could be some issues with this. For example, the cap and the flashing that are on it could obstruct the vent and make some issues with the plumbing in your home. 

Caps On Vents Can Get In The Way

A cap on your plumbing vent can get in the way of anything coming in and out of the vent. The underside of the metal cap in winter could become choked with ice as the plumbing vents will often aspirate moist air when there is nothing that goes down the drain pipes. There are other times when this may become an issue, but ice in the winter is one of the main reasons. 

During the winter, one extra problem that may show up is ice gets into the system. When the cap does open, it can let moisture out. This moisture, depending on the temperature inside the home compared to it outside the home, could easily freeze and turn to ice. When that happens, it is hard to get the plumbing system to work well at all because it is so clogged up. This makes it hard for the cap to go up or down at all and can make you need a professional. 

What are Plumbing Vents?

Plumbing vents are just pipes that will extend out from the waste pipes to the outside of your building. They will often find their way to the outside through the roof. This vent makes it easier for the sewer gases to get outside of your home rather than any of that being released in your home. These are also the way that oxygen will find its way into the waste pipes so bacteria can break down. 

The vents can come into play when it is time to keep the air pressure even on both sides of the trap while maintaining the water inside of your trap. If there is a time when the air pressure is unequal, the water would then be sucked out towards the part of the pipe that is lower in pressure. This helps everything stay as balanced as possible. 

The air pressure in these pipes should be equal throughout the whole pipe. But when water moves through the pipe, it is going to compress all of the air ahead of it, giving a positive pressure. There is a need for the buildup of pressure to be released or that positive pressure you just created will push back on the water. When air pushes backwards, the wastewater will back up through the plumbing and come out the drain. 

In a similar way, if the air is not replaced behind your water as it moves through that vent, it would start to create the negative pressure. This will suck the water out of the trap. For the most part, your venting will work well. However, if you add a cap to the process, it could cause the wrong kind of pressure to build up over time. 

The plumbing vent needs to be open so that it can do the job we just described above. A cap can definitely get in the way and may make it impossible for the system to work. Even a light cap that just sits on the top can make this a little bit difficult too. It is best to leave the cap off and let the system do the work that it needs. 

It is important to have your plumbing vents are set up the proper way. This will ensure you are able to get the right pressure and water at each stage of the game. If you are uncertain about whether the vents are working properly or if you notice that there is something wrong, then it may be time to contact a professional plumber to help you out. 

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