Gray water vent issue

[Dan Clayton]

Ran into a small issue while getting ready to run my gray water lines for the kitchen sink and bathroom vanity. Had to change the lay out and now I don’t have an area to run the gray water vent off the drain line up thru the roof that would not be in plain site. So my question is can I run the vent line up to the top of the counter and then put a nice grid cover on the top of it. I would need to do the same in the bathroom. These are two different lines and both would run to the lowest part of the main black water drain drop. My only concern is that it may allow the smell to come back up the pipe into the trailer. I’m not worried about the water backing up the pipe and into the trailer, because it is such a small amount of water going down those drains, but I am concerned about the black water smell. If the black water tank was shut off and only dropped every few days instead of leaving it opened then there may not be an issue.
Any plumbers have any thoughts out there?

[Dan Clayton]

The one thing I forgot to ask was does anyone know if I can just run a 1/2 pipe for the air vent. That size I could hide. Also after I did my post I got thinking that shutting off my tank would not make any difference since the connection is open to the drop hose.

[bryanl]

You do need to run the vent to the roof to avoid smells (and dangerous gases). I don't think half inch pipe would be sufficient to handle all cases.

The usual way to handle things if you can't route the vent through the walls or in a closet is to use a bulkhead.

On most of the trailers I have seen, each sink has its own roof vent and the tank has one as well. All of the vent lines are inch and a half. There are good reasons for this, I think.

[wkerfoot]

There is a vent which can be put on the drain line inside the cabinet. I don't remember the actual name, but my plumber neighbor called it a scooter vent. It is available at the big box hardware store, local Ace/True Value or a plumbing supply store. I think the cost is about $20.

I put one at the sink in my Liner when I plumbed the drain line. They are often used in kitchen islands where there is no access to a wall for the vent line.

Bill

[Minno]

Originally Posted by wkerfoot

There is a vent which can be put on the drain line inside the cabinet. I don't remember the actual name, but my plumber neighbor called it a scooter vent. It is available at the big box hardware store, local Ace/True Value or a plumbing supply store. I think the cost is about $20.

I put one at the sink in my Liner when I plumbed the drain line. They are often used in kitchen islands where there is no access to a wall for the vent line.

Bill

Those valves are called air admittance valves. They are discussed in another fairly recent thread:

http://www.airforums.com/forums/f163...gle-70140.html

Gray tank venting is discussed here:

http://www.airforums.com/forums/f444...sue-70525.html

Basically, you can use them under cabinets for sinks, and they work well, but you still need at least one vent from the tank going out the roof.

Chris

[wkerfoot]

Chris,

Thanks for the actual name and you are correct that it only solves the problem of venting the drain line from the sink and not the tanks.

Bill

Originally Posted by Minno

Those valves are called air admittance valves. They are discussed in another fairly recent thread:

http://www.airforums.com/forums/f163...gle-70140.html

Gray tank venting is discussed here:

http://www.airforums.com/forums/f444...sue-70525.html

Basically, you can use them under cabinets for sinks, and they work well, but you still need at least one vent from the tank going out the roof.

Chris

[Dan Clayton]

Thanks all. I went down to the Airstream dealer today and looked at their set up in a 2010 model. They have the gray water line vented under the counter. I looked at 5 trailers and they were all the same. So it's going to be an easy fix. The black tank I already have a vent tube for that one going out the roof. I was smart enought to know I was going to need that one, but since I did not have a gray water tank, I kind of had a old age moment.

[Jim Foster]

Our '83 Excella has the under counter vents as you describe for the wash water drains. It also has a roof vent for the gray tank and a roof vent for the black tank. Both roof vents pass through the trailer inside the closets, black in the street side closet and gray in the curb side closet.