Plumbing vent

[john9861]

When considering plumbing vents I'm curious as to my options. Presently I'm planning a combined vent for the gray & black tanks. Will this be sufficient for my bathroom & kitchen sinks or will they need to be tied in to the vent pipe upstream of the tanks? How about an auto vent on the kitchen sink? There will also be a washer/dryer in the kitchen. The shower has a 12 inch long drain pipe that dumps straight into the gray tank. Of course the sinks are trapped. There is also a cyclone vent on the roof. Hope this is enough info.
Thanks,
John

[loosenut]

I have one vent and it is sufficient.  Building codes can help with the size.  Mine looks to be less than 2 inches in diameter.

Mike

[FloridaCliff]

John,

I have a combined vent for my Black and Gray tanks, it is 2".

It comes almost straight up off of the Black tank and Through the roof to a vent stack.

Basically a tee facing for and aft with a reducer to 1 1/2 in the fore facing hole.

The Gray tank is vented on the vertical leg of the Black vent.

I used an auto vent in the kitchen also.

You didn't say, but I am assuming that you know to put a trap on the shower, not just a straight pipe to the Gray tank.

The only issue I have ever had with this set up was prior to the tee with the venturi, I would draw some odor into the cabin underway.  After the tee with the venturi I have zero odor being pulled in.

Cliff

[bevans6]

basically plumbing is plumbing.  The requirements on the bus are pretty much the same as for your home.  Each fixture needs to have a vent or it won't drain.  Often an air admittance valve is used for sinks and things that are a little way from the vertical vent stack.  The septic tanks need vents to the top of the structure, the roof of the bus in our case.  That vent can be combined for the grey and black tanks, and it can combine with the vent for the sinks and such.  It should be constantly rising, no horizontal sections, directly from the tank to the roof.  1.5" is usually considered large enough, but when you dump your tanks you will pull the water out of all the drain traps and you'll need to replace it before driving or you will get vapors inside the bus.

Brian

[Sean]

The requirements for Drain, Waste, and Vent (DWV) plumbing are extensively spelled out in the code, NFPA 1192, available on-line for, IIRC, about $37.  We have also covered this topic pretty comprehensively in the archives.

In all deference to the folks who claim it is the same as for buildings, there are actually quite a few differences.  For example, "wet vents," generally not allowed in fixed structures, are allowable in RV installations provided certain size requirements and limits on number of fixtures are observed.  Also, NFPA 1192 covers holding tanks, which are generally not found in fixed structures.

I strongly recommend you buy or borrow a copy of 1192.  Not only will it spell out how to do the DWV plumbing, but is also covers many other aspects of your conversion, such as emergency exits, LPG plumbing, smoke and CO detectors, toy-hauling compartments, generator installations, fresh water installations, and a handful of other pertinent topics.

-Sean
http://OurOdyssey.BlogSpot.com

[john9861]

Thanks guys,
                  Wayne helped me out on theEagle board by reminding me that the shower without a ptrap will lead to some fabulous smelling encounters while showering.    My tanks & vent pipe are located in the back bay & go toward the back of the bus through the old A/C vent then up through a closet in the bedroom adjacent to the bathroom wall. By running my vent & electrical chase in the closet I was able to keep my wall to 3/4" thick. It also means that if i have to i can access these things without removing any walls, etc. If I can use the auto vent in the kitchen it would help as it is complex to run a hard vent & tie in with the others.   

[JackConrad]

If I can use the auto vent in the kitchen it would help as it is complex to run a hard vent & tie in with the others.   

We used an "auto vent" (Studor) on our kitchen sink.  Over 10 years and no problems (or smells) so far.  Jack