Vent under sink cause of smelly trailer?

[wopachop]

My trailer smells gross come summer time. Was gone 3 weeks and come home to that sewer smell. To me it smells like gray tank.

Pretty sure my P traps are still filled with water. It must be the kitchen sink vent inside the cabinet that causes this?

I open that cabinet and hope it smells worse so i can blame the vent. But it doesnt really smell worse.

Also seems to happen after driving the trailer.

Im the 2nd owner. Ive never put any food down the drain. Dont clean dishes either the trailer is parked on a property and i take the dishes into the house to clean.

Is it just soap scum? Owned the trailer 2 years so the gray tank has been filled with shower water and drained a bunch of times. Ive never tried to sanitize it....if thats even a thing.

[dougrainer]

myredracer wrote:

wopachop wrote:
Thanks for all the info. Covered with a plastic bag and rubber band. If smell goes away i will replace the valve.

Just be aware doing that could possibly cause the P-trap to get sucked dry and you could still smell the tank.

Possibly? BUT NEVER HAS HAPPENED. Countless customers of mine over the past 30 years have done the bag trick and even closed the vent OFF and have never had the P trap go dry. Doug

PS, another Gray odor source IS the Plumbed Washer/Dryer drain P trap. Unless you have the drain tube blocked OFF or put water in the P trap(you do not have or use a Washer), then the Gray odors will come up in the Washer Dryer area cabinet. Some OEM's cap off that pipe and others leave it open.

[Lynnmor]

myredracer wrote:


Our galley tank has a vent to the roof less than 3' from the sink, plus an AAV. The vent stack in our bathroom is also less than 3' to the sink & shower. Are AAVs maybe not required in some cases but they put them in anyway? Maybe AAVs in RVs are creating more trouble than they are trying to prevent (when vent stacks are close to sinks & showers)?

I think that there is little to no planning in the RV world so they just do a one size fits all approach. In your case, I would give the drains a good test with the AAVs bagged and if the traps retain water I would just eliminate the troublesome things. My trailer has no roof vent for the galley and the bath sink is more than 3 feet, so I need to keep them, So far I have noticed no problems.

[myredracer]

Lynnmor wrote:


Not required, just permitted when the manufacturer doesn't want to do a roof vent.

I would agree. But is an AAV required if there is vent stack to the roof within a certain distance of a sink or shower?

Our galley tank has a vent to the roof less than 3' from the sink, plus an AAV. The vent stack in our bathroom is also less than 3' to the sink & shower. Are AAVs maybe not required in some cases but they put them in anyway? Maybe AAVs in RVs are creating more trouble than they are trying to prevent (when vent stacks are close to sinks & showers)?

In houses (here at least), a vent stack has to be within a certain distance of a plumbing fixture before an AAV is required/allowed (3'-5' IIRC) which happens when you have a kitchen island for ex.

[BFL13]

They used to warn against going down the road with the RV roof vents, range hood vent, and any windows open in case of losing the water in the P-traps. Would smell up the RV.

With AAVs this could be worse? I got confused about negative or positive pressure with AAVs and what pressure type happens if you drive with the windows open, but whatever--it could be a factor?

[myredracer]

wopachop wrote:
Thanks for all the info. Covered with a plastic bag and rubber band. If smell goes away i will replace the valve.

Just be aware doing that could possibly cause the P-trap to get sucked dry and you could still smell the tank.

[wopachop]

Thanks for all the info. Covered with a plastic bag and rubber band. If smell goes away i will replace the valve.

[BFL13]

That RV one seems to say they can't use one instead of a roof vent, in that the grey and black tanks must have roof vents. Perhaps it allows for longer horizontal distances away from the roof vent stack for sinks to be located.

The battle with actual stick house codes is to persuade the code makers to allow for no roof vents at all, but then they don't have black and grey tanks.

Freezing seems to be a problem with AAVs. Perhaps another thing to worry about with RVs for de-winterizing procedures?

[Lynnmor]

myredracer wrote:
We had an AAV at the kitchen sink fail in the first year of owning our TT from new. Replaced it with one from Lowes. It failed shortly afterwards. Then I installed a commercial grade Oatey one and that fixed it for good.

AAVs are required under NFPA standard 1192 which is specifically for RVs. They call it an anti-siphon vent device.

Not required, just permitted when the manufacturer doesn't want to do a roof vent.

7.6.6 Anti­Siphon Trap Vent Devices.An anti­siphon trap vent device shall be permitted to be used only as a secondary vent in accordance with the following: (1) An anti­siphon trap vent device shall be installed in accordance with the terms of its listing. (2) One anti­siphon trap vent device shall be permitted to serve not more than two fixtures. (3) Anti­siphon trap devices shall not be used as a primary vent for toilets or holding tanks. (4) When a fixture drain or main drain bypasses a holding tank, that drain shall be vented by a primary vent. (5) Anti­siphon trap vent devices shall not be used on more than two consecutive fixtures before being vented to outside atmosphere. (6) Two fixtures protected by one anti­siphon trap vent device shall be drained by a common 1 ½ in. (38.1 mm) minimum drain. (7) The device shall be installed in an accessible location that permits a free flow of air.

[BFL13]

maillemaker wrote:

AAVs are required under NFPA standard 1192 which is specifically for RVs. They call it an anti-siphon vent device.

When was the AAV added to the standard?

I don't think my 1990 Winnebago has one.

No idea about RV timing , but reading some stuff I Googled, it looks like they came into use in Can/US about twenty years ago, but only started getting code approvals around 2008 give or take. Those limited use approvals have since been expanded allowing more in stick houses/apartment buildings than originally.

That could be why I never saw any in my 2003 5er. Of course "standards" and "guides" are not "codes" AFAIK. (RVs are not stick houses for all code things apparently)

[myredracer]

maillemaker wrote:

AAVs are required under NFPA standard 1192 which is specifically for RVs. They call it an anti-siphon vent device.

When was the AAV added to the standard?

I don't think my 1990 Winnebago has one.

Ni idea when. You might have to contact NFPA to get info. like that.

You may not have an AAV if the kitchen sink is close enough to the vent pipe to the roof?

[maillemaker]

AAVs are required under NFPA standard 1192 which is specifically for RVs. They call it an anti-siphon vent device.

When was the AAV added to the standard?

I don't think my 1990 Winnebago has one.

[myredracer]

We had an AAV at the kitchen sink fail in the first year of owning our TT from new. Replaced it with one from Lowes. It failed shortly afterwards. Then I installed a commercial grade Oatey one and that fixed it for good.

AAVs are required under NFPA standard 1192 which is specifically for RVs. They call it an anti-siphon vent device.

[BFL13]

dougrainer wrote:

BFL13 wrote:
I never heard of an AAV until this thread started, so no help with that. I Googled to see what they are.

My 2003 5er didn't have any, and my stick house doesn't have any. Sort of reminds me of the dishwasher drain, where you have to leave the sink drain open as a vent for the dishwasher, but not exactly I guess. Learned something new again on this forum!

EDIT- seems they had to amend the plumbing codes a few years ago to allow these AAVs. As alternatives to roof venting, they could be handy for RVs, not just for island sinks.

https://garynsmith.net/venting-101-air-admittance-valve-pros-cons/

In 40 years and still working as a RV tech, I have never really seen a RV Gray Tank drain system from the sinks NOT HAVE a AAV. They are standard. The usual fix besides replacing is to install a ziplock bag over the AAV and secure with a rubber band. That usually fixes the smell problem. Doug

All I can say is my 2003 Komfort 5er didn't have any that I could tell. Just same sort of plumbing as the stick house. I have done work on the house and the RV plumbing at times.

The 5er had two grey tanks, one for the kitchen (galley) and one for the bathroom tub/shower and sink, each with its own roof vent. I worked on the bathroom sink drain when I changed the sink doing a reno, and also the kitchen sink double drain so I could get underneath its tap I was changing.

I don't see how I could have not noticed any AAVs. Was the same sort of plumbing as in the stick house (roof vented).

[dougrainer]

BFL13 wrote:
I never heard of an AAV until this thread started, so no help with that. I Googled to see what they are.

My 2003 5er didn't have any, and my stick house doesn't have any. Sort of reminds me of the dishwasher drain, where you have to leave the sink drain open as a vent for the dishwasher, but not exactly I guess. Learned something new again on this forum!

EDIT- seems they had to amend the plumbing codes a few years ago to allow these AAVs. As alternatives to roof venting, they could be handy for RVs, not just for island sinks.

https://garynsmith.net/venting-101-air-admittance-valve-pros-cons/

In 40 years and still working as a RV tech, I have never really seen a RV Gray Tank drain system from the sinks NOT HAVE a AAV. They are standard. The usual fix besides replacing is to install a ziplock bag over the AAV and secure with a rubber band. That usually fixes the smell problem. Doug