Blackwater tanks and plumbing - need some hints

[enthe0gen]

I'm almost to the phase in my renovation where i will be adding the combo black/grey tank and accompanying plumbing. My plan is to have a kitchen and bathroom sink and a toilet, but no shower. I'm planning on using a 20 gallon freshwater tank, and 40 gallon combo black/grey tank.

I know that the toilet needs to be mounted directly above the black/grey tank, which has been accounted for in my floor-plan. I was going to purchase this tank: http://www.plastic-mart.com/product/...lding-tank-71h.

My questions and concerns revolve around the plumbing connections from the toilet to the black/grey tank:

Do i need to have the 3" inlet location on the black tank pre-measured and pre-installed by the factory, or can i just use a hole saw and cut out the location after i mount the tank on the underside of the bus? (same for the grey water 2" inlet?) If i go the route of using a hole saw to cut out the 3" inlet location, what kind of flange or gromet would i need to make sure the connections are tight? Can any of the veterans out there point me in the right direction on the correct way to go about this? What about which parts or install kits i need to purchase? I know that i'll need an RV toilet floor flange, but what else?

Also, I purchased a Dometic 310 ReVolution Toilet and am a little nervous about how to actually get the plumbing connections to line up so there is no leakage (ewwwww). Has anyone installed this particular toilet before? Any advice to avoid a messy and smelly mess from faulty installation?

Thanks in advance for any advice you might be able to offer.

[nat_ster]

Measure, Measure and Measure again.

A residential toilet normally gets installed 13" from the back wall to the center of the 3" flange.

Measure it out inside the bus, get your layout done with masking tape. Try not to land the hole onto one of the floor ribs. Be sure on your toilet location.

Cut the main hole in the floor using a 3 3|4" metal cutting hole saw, or less preferable, a jig saw. If your floor will not be insulated, you will need a 4 1|4" to fit the lower sleeve portion of the flange through the floor also.

Now shove a nice long piece of 3" through the opening, all the way to the ground. Using a level, make sure it's plumb.

Now Measure again. This time make sure you know how and where your tank will be installed. Now you know where you need the fitting installed.

The manufacture will install the better fitting. Anything we install won't hold as well.

To route the sinks into the 3" line, all you need is a 3" to 1.5" Tee Y adapter. Some people use 2" from their sinks. Both do fine in a bus, 1.5" is cheaper. Simply install it between your toilet and the black tank.

Or for more versatility, have the manufacture install a 1.5", or 2" opening for the sinks to flow into.

Also have the company install a small 3|4" opening for your vent line. You may need others depending on what other systems you will be adding.

Nat

[enthe0gen]

Thanks nat_ster. This is invaluable information.

To reiterate what you are saying (so i know i have it correct): Find a location in the masking tap layout for the bathroom that isn't directly over a rib. Cut a 4.25" hole with a metal cutting hole saw in the floor (4.25" to accommodate the lower portion of the floor flange, correct?).

Place a 3" PVC pipe through the hole all the way to the ground, make sure it's level and plum. Re-measure where the 3" PVC inlet would need to be installed on the tank and submit this to the manufacturer so they can install a 3" pipe fitting, correct?

I sincerely appreciate the advice. I will snap some pics and update when i get to this point.

[nat_ster]

Originally Posted by enthe0gen

Thanks nat_ster. This is invaluable information.

To reiterate what you are saying (so i know i have it correct): Find a location in the masking tap layout for the bathroom that isn't directly over a rib. Cut a 4.25" hole with a metal cutting hole saw in the floor (4.25" to accommodate the lower portion of the floor flange, correct?).

Place a 3" PVC pipe through the hole all the way to the ground, make sure it's level and plum. Re-measure where the 3" PVC inlet would need to be installed on the tank and submit this to the manufacturer so they can install a 3" pipe fitting, correct?

I sincerely appreciate the advice. I will snap some pics and update when i get to this point.

Correct.

I gave measurements for ABS pipe. PVC has a thinner wall, so hole saw sizes may be smaller.

If in the budget, use ABS. Much stronger material, and far better glue connections.

Nat

[gbstewart]

When I figured out where my toilet was going, making sure not to hit a floor rib, I got my tank lined up and figured out the vent hole was going to be, drilled out the vent hole, 11/4 and put a 45 elbow on it, then mounted the tank, there is not much room between the top of the tank and the bottom of the floor. then inside I drilled out my hole in the floor 3.5 inch then 3 inch in the tank, glued in a coupler that had one end threaded female end, the toilet flange has a threaded male end, then I just screwed it into the tank flush with the floor, screwed it down, and done, pc of cake. there was no room to put a 3inch why for a grey water hook up, you would have to put a separate hole in the top of the tank like I did for the vent pipe. when a tank is right up against the floor the only room you have is the space between the floor and the ribs,
gbstewart