Plumbing kitchen gray tank drain into front black/gray drain

[leefl]

Our 5er has 3 sewer drains.
The front one (easy access) is for the front bathroom black and gray tanks (seperate dump valves obviously)
The second one is for the kitchen gray tank and is under the dinette slide (and I have to crawl under the slide to connect a sewer hose for dumping, while already setup at camp)
The third is for the rear bunk 1/2 bath

I'm planning to remove the bayonet connector from the front drain, and replace with a 3" tee, and (possibly) remove the valve from the kitchen drain, plumbing that drain into the tee at the front drain, with a new dump valve closer to that drain.

The question is whether I can leave the flange from the backside of one of the dump valves, and just connect another flange to it, without the dump valve in-between ?
I haven't tried to dismantle it yet, and am not sure of how the interior surfaces of those flanges are, and thus whether I can safely just connect two flanges together (e.g.: is there enough space for the large washer/seal between the two flanges ... or too much gap, or no space at all ?)

So, to try to make my plan clearer: -

Remove dump valve from kitchen drain, leaving just the flange which is currently bolted to the dump valve
Connect a flange with a 3" spigot fitting directly to the existing flange
Connect a 90deg elbow with hub-to-hub fittings to that spigot (glued)
connect a length of pipe into that
connect a new dump valve to that pipe
Remove the existing bayonet fitting from the front drain, and replace with a 3" tee, with hub fittings
Connect the new dump valve into one inlet on the tee
Connect a new bayonet-spigot connector into the outlet of the tee


Thoughts ?

[leefl]

I drew a picture



You can see where I'd want to connect the two flanges directly together, having removed the old dump valve

[CaptnJohn]

My 5er has 3 drains. Front is bath gray, 2nd is black, and 3rd kitchen gray...

[leefl]

Originally Posted by CaptnJohn

My 5er has 3 drains. Front is bath gray, 2nd is black, and 3rd kitchen gray...

I'm surprised that your front black and gray drains aren't already connected together like ours are

[CaptnJohn]

Originally Posted by leefl

I'm surprised that your front black and gray drains aren't already connected together like ours are

I should have said 3 tanks. All are connected to the same drain pipe. Pull black, then kitchen gray, then shower gray...

[dieselbobcat]

Why not just leave the existing valve in place, open and remove the handle to prevent use?

Easy enough to undo the mod if ever needed and no worries about sealing the flanges together....

-OR-

Replace troublesome dump valve with a cable operated unit and mount the handle in easy reach. They also offer electric units...

[bob caldwell]

My galley tank handle was under slide....I changed the cap to one that has a garden hose attachment thread....then between it and valve, bored a hole in pipe, ran a length of pvc and hose toward front grey/black tank valve, added a 3" valve, and plumbed that into the side of grey/black tank outlet, between cap and valve, and now leave factory valve on galley tank open. But, if only needing to drain galley, I use that factory valve and a garden hose

[leefl]

Originally Posted by dieselbobcat

Why not just leave the existing valve in place, open and remove the handle to prevent use?

Easy enough to undo the mod if ever needed and no worries about sealing the flanges together....

-OR-

Replace troublesome dump valve with a cable operated unit and mount the handle in easy reach. They also offer electric units...

It's not just that the valve is hard to reach, it's also that is hard to hook up the sewer hose, and I really don't want to have to carry around 3 sewer hoses and multiple tees

[leefl]

I guess I could leave factory valve in place but open, just depends on angle/position between the two connections. The galley one currently protrudes further, so I'll see once I have the tee connector and will measure

[leefl]

Does anyone know where I could buy 3" black ABS DWV pipe in small quantities

Lowes sell 5ft lengths (great) but you have to buy in multiples of 4 (and I only need under 4ft total), and they don't stock locally (so I'd have to get it delivered). Paying over $60 for 4 lengths of pipe, when I only need one isn't a great option.

They also (in theory) sell a 10ft length, but it's not stocked locally, and neither delivery to store, or parcel shipping are available


An amazon seller sells a 2ft length, but I don't think that's quite enough.

Ace Hardware don't stock ABS pipe, only PVC

[TURBS]

Go to your local plumber!
They always have pipe laying around in different lengths


2008 2500hd Duramax
2015 Columbus 320RS
2016 nights camped "0"
2015 nights camped "34"

[leefl]

Originally Posted by TURBS

Go to your local plumber!
They always have pipe laying around in different lengths

I'm not sure any of the local plumbers would be happy if I just showed up at their house
but I guess I could pick one out of the phone book and try calling one at random

[TURBS]

Originally Posted by leefl

I'm not sure any of the local plumbers would be happy if I just showed up at their house

but I guess I could pick one out of the phone book and try calling one at random

I go to my local plumber all the time for odds and pieces.

[leefl]

Originally Posted by TURBS

I go to my local plumber all the time for odds and pieces.

I'm used to doing most plumbing myself, but I guess it's not a bad idea to find a local guy that can supply me with stuff that I can't get from Lowes

[TURBS]

Originally Posted by leefl

I'm used to doing most plumbing myself, but I guess it's not a bad idea to find a local guy that can supply me with stuff that I can't get from Lowes

Exactly!

[leefl]

So, I'm toying with 3 options, and would like folks input: -

1. Replace the existing valve (top right of my drawing) with a cable-release one, so that I can easily access the handle, but don't fit any secondary valve near the new Tee (my only concern with this is whether stuff from the black-tank flush will wash up into the new length of pipe and get left there (tho' in theory that shouldn't be an issue so long as I always flush the galley tank after, tho' on short stays there might not be much to flush)

2. Leave the existing valve, but also add a secondary valve near the Tee. That should handle the above concern (of black tank contents washing up into the new pipe), but if I left the existing valve open and only use the new valve then I'll have water from the galley tank always sitting in the new pipe adding weight and possibly causing a breakage (more of a concern if travelling with a non-empty tank)

3. Combo of both. Replace existing valve with cable release, AND put the old valve (with new flanges) near the Tee, so that I can both keep the black tank from washing back up into the new pipe AND keep galley tank water weight out of the new pipe.

[leefl]

Ordered all the parts for option #3
Most should be here tomorrow, but will have to wait an extra few days for the pipe and new valve

[M&K Hoffman]

Originally Posted by leefl

Does anyone know where I could buy 3" black ABS DWV pipe in small quantities

Lowes sell 5ft lengths (great) but you have to buy in multiples of 4 (and I only need under 4ft total), and they don't stock locally (so I'd have to get it delivered). Paying over $60 for 4 lengths of pipe, when I only need one isn't a great option.

They also (in theory) sell a 10ft length, but it's not stocked locally, and neither delivery to store, or parcel shipping are available


An amazon seller sells a 2ft length, but I don't think that's quite enough.

Ace Hardware don't stock ABS pipe, only PVC

Wow,just for fun I looked around and ABS is hard to find. It is not stocked anywhere here as I believe it cannot be used in residential applications. Random searched turned up that WalMart will ship me a 10' joint of 3" ABS for $5 shipping.
Fortunately for me we bought some rural property many years back that had an old 12' x 60' mobile home on the property. When we tore down the MH I kept every bit of the ABS that was in it so I have a fairly good stash of 1-1/2", 2" and 3".

with your project!

[leefl]

Originally Posted by M&K Hoffman

Wow,just for fun I looked around and ABS is hard to find. It is not stocked anywhere here as I believe it cannot be used in residential applications. Random searched turned up that WalMart will ship me a 10' joint of 3" ABS for $5 shipping.
Fortunately for me we bought some rural property many years back that had an old 12' x 60' mobile home on the property. When we tore down the MH I kept every bit of the ABS that was in it so I have a fairly good stash of 1-1/2", 2" and 3".

with your project!

Thanks!
I ordered 10ft of 3" from jet.com
I think it's the same seller as on Walmart but with free shipping.
Lowe's sell 5ft lengths for $15, but you have to buy 4, and no stock locally so have to get delivered. The 10ft length from Lowe's is special order and would take weeks to get delivered.
I'm hoping to get the work done next weekend, after getting new tires fitted, but depends on time and weather of course

[leefl]

I finished this mod over the last week, and posted a full write-up here: -
http://www.forestriverforums.com/for...in-107840.html