Replacing the Air Admittance Valve For RV (Rooftop, Sink)

The foul odor can ruin the scenery. You get up in the morning, open the window shades, and look out to see the most beautiful sunrise ever. Then you take in a breath of …fresh…air…cough. In that breath your nose wrinkles due to the foul odor. It is not a good way to start the day.

The air admittance valve has been around for a long time. It is used in traditional homes, apartments, and other locations that contain a bathroom. Their main purpose is to let air into your plumbing while not letting any air or odors out.

To learn more about this topic, just continue to read our article. It contains the information you want to know about when you need to fix a foul odor problem. Take a few minutes to see how this information helps you solve this problem.

RV What is An Air Admittance Valve?


An RV air admittance valve is the same thing as one for traditional homes and apartments. It is a cap that goes on one specific opening in your plumbing to seal it off.

Once installed, not only does this valve seal the pipe and keep foul odors from entering your RV, but it also allows air into the pipes to prevent a vacuum from forming inside your plumbing system.

Everyone’s plumbing works the same. Inside, the pipes are full of air. Then when water is poured down the drains, it pushes the air already there out. The water takes the place of the air momentarily but without incoming air, creates a vacuum.

The air admittance valve solves this problem. The rushing water while pushing the air out needs to draw air into the pipes to keep this vacuum from forming. What the air admittance valve does is allow air to enter the pipes and replace the water as it vacates those same pipes.

The good thing about these valves, besides that function, is that the incoming air blocks any bad odors that may arise from your holding tanks. Your pipes stay clear and you get a nice-smelling RV interior, that is a win-win situation.

How Does The RV Air Admittance Valve Work?

This valve operates very simply. When the water passes through the pipes, the valve opens to let air in. The incoming air is important as a vacuum could and would suck the water out of the P Trap.

It is the water in the P trap that creates the obstacle that blocks the bad odors from entering your RV. With that water gone, the odor has a free roadway to rise and continue through all of your pipes.

The end result is without the water in the P Trap, your RV will smell as bad as the black holding tank. This means that while not a major part of your RV, this smaller part still plays a vital role in your overall comfort and enjoyment of the great outdoors.

When you do smell the black tank odor or even the gray tank odor, you know that the source of the problem could be the air admittance valve. When your nose detects that bad odor and it will be worse at your kitchen sink, you know it is time to find a replacement valve.

What is The Downside To An Air Admittance Valve?


There are two major downsides to this vital part. One is that it can break or wear out on you. According to some manufacturers, you should be getting up to 500,000 uses out of one valve. So it is not a part you will replace frequently.

That number of uses translates into roughly 20 to 30 years so you do not have to rush out and buy one unless the plumbing in your RV is very old. However, some air admittance valves do wear out, some sooner than later, and you may have to change it in five or ten years.

That is normal but if you are changing it every couple of years then you may have bought bad air admittance valves. Or you may be experiencing the second downside to this vital part.

That second disappointment would be a rodent problem. It has been tested and given enough time and enough rodents, your air admittance valve could be full of holes.

Those holes were from the teeth of the mice or rats that have been able to climb up your pipes to this valve. The solution to both of these downsides is for you to replace the valves and call in an exterminator to get rid of the rodents.

The signs that you have an air admittance valve problem are clogs and sewer odors.

Rooftop RV Air Admittance Valve

Generally, you will not find an air admittance valve on the roof of your RV> They are located under the bathroom and kitchen sinks. This means you do not have to climb up a ladder to replace them.

Also, if they were on the roof, you would never know if one was bad as you would never smell the odor inside your RV. A roof vent in a traditional home would be similar to this RV part.

But that is if you have access to a wall. A kitchen island with a sink may have an air admittance valve but in some areas that may not be code. To make sure there is not a valve on your RV’s roof, check out your roof vents or look in your owner’s manual.

The key to keeping your RV smelling like roses is to make sure you do not buy a cheap model unless that is your only option at the time. These cheaper options have been known to fail after three weeks of use.

When you can, make sure to buy the better quality valves even if they cost a bit more than other brands.

RV Sink Air Admittance Valve


In most RVs, you may find up to 2 air admittance valves. One is located in the kitchen and the other will be in the bathroom. If you have more than one bathroom check the others to see if there is one inside of the second washroom.

Usually, there will only be one air admittance valve in a bathroom. That is because the shower and sink in that room share the same holding tank. There is no need to add a second air admittance valve to the room.

What is in your second bathroom depends on your RV’s manufacturer and if they deem it necessary to add one there. The kitchen will only have one air admittance valve.

Generally, while you may smell the foul odor all over your RV, it will be strongest in the kitchen, specifically, under the kitchen sink. When you open that cabinet door, you should be overpowered by the smell.

When you detect that odor, you know you have to go out and buy a new valve right away. While not harmful, getting rid of that smell is essential for comfort and normal living.

Where Should The Air Admittance Valve Be Located?

The two general locations have already been given. You should find these valves in your bathroom and kitchen. Unless RV makers put one at the roof level, there should not be one at that height.

The specific locations are under the sinks and right over your P Trap. The following image will provide a better description than 1000 words could do in this instance:


This does not mean that RV makers do not get creative and find other locations for this part. But this is the ideal location and where you should look first. The image also provides you with a good picture of what one of these air admittance valves looks like.

There are different colors, usually black, so do not ignore those colors as they are still air admittance valves. It is a good idea to buy a couple of these valves and keep one or two as a spare.

That way you can make the change without having to run into town and only have the option of buying a cheap one that will not last very long.

How To Replace An Air Admittance Valve In RVs

In all RVs and trailers, there are simple parts to remove and replace and there are some very difficult parts to remove and replace. Fortunately, the air admittance valve is among the former group and not the latter one.

The hardest part of removing the old valve and installing the new one is getting down to the floor to do the work. Then getting back up again. As you get older, those knees just do not want to bend in those directions.

Once you are on the floor, and as you can see from the image above, you just need to unscrew the air admittance valve and screw in its replacement. That is if the threads are cooperating.

You may find them a bit tight if the valve has been in place for a long time. Or you may find that the RV maker used glue or plumber’s putty to help secure the threads.

In those situations, you may need a good monkey wrench to loosen the valve and then use your hand to unscrew it. Just do not pull too hard because the valve and the pipes are not very strong.

They are made from plastic-like materials and do not have the strength of the old metal, iron, or copper pipes. Once you get the old one off, you just crew the new one in place.

You want it tight but not too tight so watch how you screw in that replacement. It is possible to ruin both the valve and the pipe attached to it if you go too tight.

The good news is that there should not be any water mess when you do this task. The valve is up high enough that any water in the P Trap should not escape. Some owners have taken off the P Trap to do this work. It is up to you which method you use.

Best Air Admittance Valve For RV

This turns out to be a part that no one has an interest in ranking from best to worst. There are no top 5, 10, or even 20 best lists available for the air admittance valve.

We will give you some brands that should be good to put you on the right track. But even cheap ones serve a purpose when you are stuck in small rural areas with a limited selection to choose between.

1. Studor 20349 Redi-Vent Air Admittance Valve with ABS Adapter- this valve works with 1 1/2 to 2-inch pipes and is a black and white color. It will work on one pipe or up to 20 drain fixture units on the same system.

Plus, it creates circulation to protect the water in the P Trap as well as uses gravity to close the valve when air is not needed in the pipes. Then it comes with a rodent protection system and helps keep bugs and other foreign objects out.

Right now at Amazon, it is selling for just under $14. Its temperature rating is from -40 to +150 degrees F.

2. Oatey 39012 1.5 in. NPT ABS in-Line Vent- Colorado residents be wary of any local state laws governing RVs and this specific part. It has been said that only white is allowed and this model is black.

This valve is made from ABS plastic and is spring-loaded. The spring opens with negative pressure and closes with positive pressure. This model is good for all types of drain systems including kitchen and bathroom sinks as well as shower drains.

The ad says it is also available in Chrome and this part sells on Amazon for $7.67.

3. Lasalle Bristol 74PV240BB Vent Valve- this air admittance valve is only one and a half inches in size and opens and closes automatically to keep your plumbing flowing normally.

With the built-in threads, it will screw on and off easily making replacement a snap. Also, it is designed to meet all plumbing standards even though the color is black.

The current price on Amazon is just over $22 and do not let the images fool you. It does not come with the extension shown in the pictures beside the product description. You should only receive the cap.

4. 1-1/2 inch Tuuber Vent 2x Superior Seal Air Admittance Valve- the overall size of this valve is 3 x 3 x 2.5 and it fits pipes measuring 1 1/2 inches in diameter.

Plus, it meets with ASSE 1050, and ASSE 1051 standards and is white so you should be able to use it no matter which state you live in. Its dual sealing system makes sure that no foul odor escapes your pipes and into your RV.

Also, it works automatically so you can put it on your pipes and forget about it. That is until you start to smell a bad odor once again. It opens with negative pressure and closes with positive pressure. The cost is $18.50 on Amazon

What To Look For In An Air Admittance Valve


1. Brand- in this situation, the brand is one of the more important criteria to use. If you buy a no-name brand there is no telling what you will get or how long it will last. Most top brands will last up to 30 years while cheaper ones may not last 1 year.

2. Price- this is another important criterion but not for your budget. You can buy the cheaper models but again, there is no guarantee that it will last a long time. Usually, the more expensive models are the best ones to buy and have a better chance of lasting that 30 years.

3. Construction material- no matter what you do, you will find that these parts are made of plastic. But there is a difference in the quality of plastics used to make these and other parts. Make sure to get one made from the best plastic materials.

4. Size- take accurate measurements so you get the air admittance valve made for your pipe’s diameter. If you can get a valve with an adaptor, all the better as that will give you some leeway if you want to change the size of your plumbing.

5. Installation- buy the one that will be easy to install. It is already hard enough to get under the sink so do not add to your troubles by picking one that is hard to install.

Some Additional Words

You may not have heard about this part before and that is okay. It is a small minor part that does a big job for you. In your lifetime, you may only have to replace this part once so it is usually not talked about.

However, this air admittance valve contributes greatly to your comfort and enjoyment of the surrounding scenery. It keeps your RV smelling nice.

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