WHere do your gray and black vent tubes go?

[Bystickel]

I'm reconstructing our plumbing and need to add vents for the black and (new) gray water tanks.

I assume I want the gray vent to reach above the height of the sink drain. I'd like to avoid adding any vents to the outer skin.

Could I run a long tube way up between the inner and outer skins, and then have it loop back down and terminate beneath the floor or have them poke through the belly skin?

Any advice is appreciated!

[dznf0g]

Definitely needs to go outside to avoid gas and odor buildup....and I don't believe the thru floor is a good idea. They should go through the roof.

[markdoane]

I'd be sure you use a large enough vent tube and route it as high as possible before you turn it down.

Otherwise you could end up with a slosh siphon if you hit the brakes or go around a sharp curve.

Your tank contents could end up on the highway.

But maybe that's a good thing?

[truckasaurus]

With a disclaimer because I am not an expert on this. I think RV code is a 1 1/2” through roof vent. My first trailer had 5/8” vents with Sealand charcoal filters through the wall and I had no problems at all but that trailer used a pump to dump the tanks. I am curious to see if a grey tank can gravity dump fast with just a 5/8” vent and fixtures using Hepflo traps rather than p traps; it seems like it would be good?

[bibbs]

Can you tie the two tank vents together, and pipe it out the original spot ?

[jeffmc306]

Bystickel, for reference, I checked the parts manual for our 2019 Globetrotter’s plumbing and found they used two 1 1/2” PVC pipes for the tank vents.

As others have mentioned, you’ll want to vent through the roof for proper operation.

Thought it might help you!

[Bystickel]

Thank you for the replies!

The original vent pipe (I think it was the original) went into the wall behind the toilet turned up, and then ended. I'm not sure if it used to go farther up or not. I'll look at the outer skin for signs of a vent, but I don't think there was one.

1 1/2" vents on the new models, wow. I don't see being able to do anything like that.

One thought I had was to add hose fittings to the vent lines so that I could also do a flush when desired. Vent tubes the size of garden hose would be about as large as I had imagined using. It's tough to figure out a solution that isn't going to have a negative impact on our interior aesthetics.

As far as the gray tank draining speed, I don't expect it to be quick, or to drain fully unless the trailer is tilted. Some will always remain. There's only 4" of depth to work with under there, and the line to the dump valve is horizontal and level with the 'tank". I know the flow will slow a lot as the level drops. Since we previously had no gray tank at all, I think it'll still be a nice upgrade.

[Glenritas]

You need 1 1/2” vent pipes to each tank so they can drain at a reasonable flow . Your black tank should have a 3” valve and plumbing.
Your gray tank needs a 1 1/2” vent also . It will have a 1 1/2” valve and plumbing, 3” would make draining fast at the dump station .

With all the new campers on the road the dump station lines will be longer , so the faster you can dump the better . You don’t want to be “that” guy that holds up the line .

You can hide the vent lines in a closet on the way to the roof or you could take them up in the closet at least a foot higher then the highest drain the make a U turn down and out through the floor to the outside.

[57Vintage]

Originally Posted by truckasaurus

With a disclaimer because I am not an expert on this. I think RV code is a 1 1/2” through roof vent. My first trailer had 5/8” vents with Sealand charcoal filters through the wall and I had no problems at all but that trailer used a pump to dump the tanks. I am curious to see if a grey tank can gravity dump fast with just a 5/8” vent and fixtures using Hepflo traps rather than p traps; it seems like it would be good?

I used the original vent size for my 58 (1") and it seems to work fine for both BW and GW. Although I must add that I use a macerator pump on my GW tanks to speed things up. I can divert the GW around or through the BW tank to aid in cleaning. This is the plumbing nightmare I created to do this (upside down on my bench before installation).



I kept the original copper fittings at the roof, polished them and cleared. I call it my one concession to steam punk. It was in the bathroom closet, which we deleted, so now its visible above the sink.