Under sink vent

[Garypowell]

Just like many others I have had that "smell" under my kitchen and bathroom sink. I changed out the vent valves and the smell persisted under the kitchen sink. I then systematically went through all the piping and sink drains and reseated them all...and the smell persisted.

I then dropped the bottom to see if I had a leak....and some water came out. But upon further inspection and a few days determined it was just water from wheel splash. Not good in itself but not the cause of the smell. But just to be sure I closed up the hole where the pipes go through with foam.

And the smell persisted.

So I removed the vent valve and put some Saran wrap over the hole and screwed the vent valve back in......and the smell is gone!

Obviously another bad (but unfortunately new) vent valve.

I did that 2 weeks ago....having the under sink vent valve on #2 tank closed off. Besides the absence of smell I see no different operation in the kitchen sinks themselves.

I understand that many times things are done because of RIVA rules.....or general plumbing practices. But if I see no difference in the way the sink operates then why do I need this troublesome vent valve.

And that is my question to you plumbers out there......am I causing any long/short term problems by simply plugging up this vent?


​Thanks,

 

[scottyb]

Just like many others I have had that "smell" under my kitchen and bathroom sink. I changed out the vent valves and the smell persisted under the kitchen sink. I then systematically went through all the piping and sink drains and reseated them all...and the smell persisted.

I then dropped the bottom to see if I had a leak....and some water came out. But upon further inspection and a few days determined it was just water from wheel splash. Not good in itself but not the cause of the smell. But just to be sure I closed up the hole where the pipes go through with foam.

And the smell persisted.

So I removed the vent valve and put some Saran wrap over the hole and screwed the vent valve back in......and the smell is gone!

Obviously another bad (but unfortunately new) vent valve.

I did that 2 weeks ago....having the under sink vent valve on #2 tank closed off. Besides the absence of smell I see no different operation in the kitchen sinks themselves.

I understand that many times things are done because of RIVA rules.....or general plumbing practices. But if I see no difference in the way the sink operates then why do I need this troublesome vent valve.

And that is my question to you plumbers out there......am I causing any long/short term problems by simply plugging up this vent?


​Thanks,

Good question and I am having the same problem. I know I have read where a few have installed a threaded plug in place of the vent. I was going to try to re-visit those topics before doing so.

 

[branson4020]

Without the air admittance valve it's very remotely possible for the water to be sucked out of the sink trap.

 

[Garypowell]

Bob,

thanks.......I think it might happen when we drain out a lot of water. But we don't do the dishes since we have a dishwasher.

Probaly might be best to add some water after a dump too.

 

[brianharrison]

And that is my question to you plumbers out there......am I causing any long/short term problems by simply plugging up this vent?


​Thanks,

Hi Gary, No problems that I can think of - other than the one mentioned that the P-Trap can be siphoned dry by water flowing downstream of the trap.

But as with all safety/code devices that are removed or altered, owners assume all responsibility for modification.

I have just replaced the valve a couple of times until I found a working one - it is low cost. My reasoning is that when I sell the coach, it has all the required safety/code devices in place. I am getting old, I can barely remember what I did yesterday.......let alone replacing/restoring mods made a couple of years earlier......

Brian

 

[azbigfoot]

I gave up and replaced them with plugs. No more smell. The P-traps will be suctioned out when you drain the grey tanks. It has happened to me. Then the smell will be really bad. I just refill them by running some water in the sinks and shower after I dump them. The alternative is Home Depot sells some fairly expensive Studor air admittance valves ... like $30 a pop. I imagine they may work better than the $6 version installed by Heartland.

 

[Randy]

I am on our 4th travel trailer or 5th wheel with the same problem. Plug it and remember to add water to the P-trap
to block the smell from the tank. Randy, Santha and the Poodles

 

[Bohemian]

The purpose of the vent is to allow air to enter the drain pipe and assure that the water flows down the drain. In your home the vent is connected to a vent pipe that goes up and out your roof. If a pipe has to much water/junk in it, it can cause a blockage and prevent flow because air can not move into the pipe and replace the water/junk. This is a vacuum lock. If the water flows without it ...

 

[maldam]

Kitchen grey tank: Roof vent + under sink vent.

Black tank: Roof vent.

Bathroom grey tank: One vent on both sides of trailer (Shower is on one side, sink the other).

Occasionally, we'll come back to the trailer after being away from it for a few hours, and there is an awful smell. Don't know where it is coming from.

Maybe from this vent under the sink ? Why do I need it if there is a vent on the roof ?

How can I find out where the smell is coming from ? It doesn't seem to be worse at any particular place.

Thanks.

 

[cookie]

It is difficult to pin down the source of those odors.
You pretty much have to do everything to try and eliminate them.
One thing that I have done and it did the trick for me was to seal around the vent pipes on the roof.
Take the mushroom caps off and seal around the vent pipes. Then re-install the caps.
You can try to put a baggie over the air admittance valve under your sinks and secure them with a rubber band.
If the odor was coming from there the baggies will stop it.
Another thing worth noting is that at one time we had an awful odor. Turned out it was a small propane leak.
Not enough to trip the detector, but enough to smell.

Peace
Dave

 

[maldam]

One thing that I have done and it did the trick for me was to seal the vents on the roof.
Take the mushroom caps off and seal around the vent pipes. Then re-install the caps.
You can try to put a baggie over the air admittance valve under your sinks and secure them with a rubber band.

Peace
Dave

I don't understand what you did here and why. I take it you DON'T mean you sealed off completely the vents to the open air ? But that you took off the mushroom caps, sealed AROUND the pipe, i.e covered any gaps between the pipe and the roof lining ? Why would this make any difference ?

Yes, we have put a bag with an elastic band (DW's suggestion !) over the under the sink valve. We'll see if that makes any difference. Still don't understand the need for this valve if I have a vent pipe to the roof.

Thanks for your reply.

 

[cookie]

I don't understand what you did here and why. I take it you DON'T mean you sealed off completely the vents to the open air ? But that you took off the mushroom caps, sealed AROUND the pipe, i.e covered any gaps between the pipe and the roof lining ? Why would this make any difference ?
Thanks for your reply.

Well, when things are running that suck air into the coach things like dust and odors can also be drawn in.
Things like the over the range exhaust fan and AC units.
Some how some way that vent air from the roof vents gets sucked into the gap between the roof and ceiling and eventually make it to the living area.
And yes you are correct, I sealed around the vent pipes.
This made a huge difference in our rig especially when the front AC was running.
And thanks for pointing out my error. I did edit my previous post.

Peace
Dave

 

[maldam]

Well, when things are running that suck air into the coach things like dust and odors can also be drawn in.
Things like the over the range exhaust fan and AC units.
Some how some way that vent air from the roof vents gets sucked into the gap between the roof and ceiling and eventually make it to the living area.


Peace
Dave

Actually, I believe the range exhaust fan sucks air from INSIDE the coach to the outside. (Unless your coach is air tight and sucks up air through the toilet. In fact, we've found that we have to have the window open a bit in the toilet, otherwise, with the toilet exhaust fan on, smelly air does indeed get up from the black tank and makes the environment even more blue !). So we should not get a problem from that. (But keep some air coming into the coach when you've got the range exhaust fan on). BUT I think the AC sucks air from outside, cools it down, and blows it INTO the coach.

All I know is that this morning, when I had the AC on, and the door OPEN, (to blow the hot interior air OUT), the smell started to get worse. Yesterday I took a picture of the roof. When I consulted this, I found that the AC intake is about 4' away from the black water vent and about the same horizontal level. So I am thinking, that the AC is sucking in air from the black water vent ????!!!!!!!

So, what to do ?

Option One is to put on one of those vents that goes around in circles and the smelly air goes out horizontally. Only trouble is that the wind often blows from a direction that would make the smelly air point right into the AC inlet !

Option Two is to make the black water vent higher.

I think I'm going with Option 2.

I'll let you know how it works out. And what do people think about my theories above ?

 

[Miller0758]

AC on? Man, that sure sounds good

 

[cookie]

You can do what you feel most comfortable doing, but I think the easiest would be to go up on the roof with a #2 square screw driver and a tube of caulk or a can spray expanding foam.
Your theory about the range hood is only partially correct. It does in fact suck air from the inside of the coach but that air has to be replenished, so it does in fact suck in outside air.
The AC does not use outside air. I recirculates the inside air.
But, if there is any lack of sealing in the AC plenum it will suck air from the attic. Smelly air.

Peace
Dave