Black/Gray Tank Vent

kamoo · 06-21-2009, 10:29 AM

I know this has been discussed a few times but I am having trouble figuring the best way to do this. I really didnt want to cut a hole in the roof (or out the side) to vent my combined tank but if I have to then so be it. I have also seen some charcoal filters for boats, not real cheap. Does anyone have a cretive way to take care of venting? Home Depot has some spring loaded vents (pop vent?) that go on the sink drain side, when a drain is opened the vent opens and when the water stops running it shuts. Would this work? Also, if I have to go through the roof, can you T off of the sink drain and run the vent off of this instead of cutting another hole through the floor?

Here is a similar spring loaded vent http://www.oatey.com/Channel/Shared/Pro ... 0_DFU.html

kamoo · 06-21-2009, 11:07 AM

I would assume that the spring vent wouldnt allow gasses to escape until you run the drain. As far as I know, boats just have a vent out of the side (1/2" - 3/8" I think) with no filter or anything. You get a whiff from time to time but it isnt usually bad or constant. When you pump out the tank you get the wonderful smell but its only for a few mins. Its not having another hole that bothers me, sealing it up is no problem, it is cutting the holes through the metal and routing the pipe that sucks. The stupid hole for the toilet has eaten two drill batteries and it isnt through yet.

elkoskoolie · 06-21-2009, 03:50 PM

My bus had a roof vent near the tank area. I made a masonite replacement for the ceiling cover, and cut a hole a hair to fit a 1 1/2" PVC threaded close nipple. A threaded piece on the roof side, and a 90 degree elbow and 1 1/2 hose barb inside and some caulk holds it tight. Then just ran some corrugated 1 1/2" sump pump discharge hose down the wall across the floor to the hole accessing the waste tank. No cutting, no odor, no messing with PVC to get the angles and lenghts just right... The corrugated hose works very well, even if you do need to cut a hole.

kamoo · 06-21-2009, 06:38 PM

Has anyone used something like this? Think this could be used under the floor?
http://www.jamestowndistributors.com/us ... aste+Tanks
http://www.jamestowndistributors.com/us ... ent+Filter

paul iossi · 06-21-2009, 06:55 PM

it sure looks like a $100 marine type charcoal filter, they work good at eliminating the stink, just needs to be replaced yearly. it needs to be mounted high enough that it will stay clean and dry, if it gets contaminated with stuff it will need to be replaced. all that you need is to let air out of the tank when you fill it and to let air into the tank when you empty it, it's not like in a house where you need a 3'' stack so that frost doesn't close the vent off in the dead of winter. you need to vent the sinks and shower so that water stays in the traps and keeps sewer gas from coming into the living space, not so critical with seperate grey and black tanks but grey tanks can get funky smelling.

kamoo · 06-22-2009, 06:36 PM

So through the roof it is! I have a few more questions. So the toilet will sit directly over the tank with the standard 3" pipe going into a slip grommet. I will have a sink on both sides of the bus, no shower. Can I run the two sink drains with 1.5" line into a y or t that goes into 1 x 1.5" pipe into the tank? Do you typically run the vent line (using 1.5") into its own inlet into the tank or would I come off of the sink drain pipe? If coming off of the sink drain, do you need a seperate vent for the other sink or would being on the same drain take care of this? I can draw a pic if needed, need a quickie on how to post it on here.

paul iossi · 06-22-2009, 07:53 PM

a vent direct from the tank should be sufficient, but if it's easier yo vent one of the drain lines that will work also.

GoneCamping · 06-23-2009, 09:36 PM

I ran the kitchen sink, bathroom sink, and shower drain all into a single 1.5" line going into the tank, and used a sererate 1.5" for the roof vent. Something you might want to keep in mind, that pipe going up and through the roof, find some way to support it so that it doesn't push it's way down on the slip joint. You want it into the slip joint, but no additional pressure like from vibrations while driving down the road. I didn't do this at first and the vent stack pushed too hard on the slip joint gasket and caused some problems. I have since added a pipe clamp that attaches to the underside of the floor to prevent any downward pressure from the pipe.

I also ran seperate vents for the gray & black, and in retrospect I guess I could have got away with putting in a "Y" to connect the two and running only one pipe up through the roof.

In the picture below the vent pipe is the 1.5" in the foreground... The second (rear) pipe is the drain pipe, the one coming down from the top comes from the bathroom sink, the drain from the kitchen sink & shower are coming across from the other side of the bus and "Y" into the other pipe just before dropping through the cargo floor and into the tank. You'll note I've tried to keep all plumbing that crossed from one side of the bus to the other all together in one corner of my cargo box...

kamoo · 06-23-2009, 10:06 PM

GC - Thanks for the pic! I never thought about supporting the vent pipe, Ill try to use a coupling above and below the floor to keep it from moving up and down. How did you vent your sink drains?

GoneCamping · 06-24-2009, 10:29 PM

Can't find a picture of it, but I used an under the counter vacuum breaker, it has a check valve built in, it's piped in from just above or below the trap (I honestly don't remember), goes up beside the side of the sink bowl. I got it out of a 5th wheel, that's how they had their sinks plumbed so I just used it like they had it...

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