Holding tank outlet info needed

[Cubey]

I bought a new tank for my Class B which had one at time but the previous owner removed it for what ever reason. I found a new one, ordered it and installed it almost completely now.

One thing that I am a bit stumped on is how do you connect up your drain piping to it? It has a 3" outlet but it's a bit oversized compared to 3" schedule 40 pipe.

I bought a 3" rubber coupler for pipes but it's a bit too small, however light use of a heat gun on the coupler may make it pliable enough to get on the tank. Is that the normal method for a drain hookup?

I had to use the heat gun lightly on the inlet grommet as well. Not enough to melt it, just enough to soften it up to get it down in the tank. It worked perfectly.

I have attached a photo of the tank's outlet.

[RV Wizard]

Some good thick sealant like poly-butyl around the pipe inserted in the outlet and a couple of hose clamps tightened down usually will hold the connection.

[Cubey]

I also emailed the manufacturer (Ronco) and asked them and that's what they replied saying also. I don't/didn't think a 3" pipe would fit into it.. but I guess I'll cut a piece the size I need and see.

[jesilvas]

Just put 3" pipe in. Or a 3" spigot end of a valve adapter flange. Some good sealer, we use 501LSW dicor, and hose clamp it.

[Cubey]

A hose clamp honestly seems to do nothing but I have one on anyway. I've attached a photo of the final product below. This is a restoration of how the original tank and drain setup was.

The only deviation is inside at the drain coming from the bathroom sink just before it enters the tank on the top. It used to have an ABS 90 degree elbow then a straight, short rubber/metal clamp on a very short straight piece of straight pipe. That is very hard to deal with in such a tight place and could allow for pipe breakage or even tank damage if the tank were to shift a bit.

Now it has a rubber 90 degree elbow (photo below) which allows for more movement/vibration tolerance. I have also put a new, better one on the pipe from the shower and gally sink drains that also allows for better vibration tolerance.

I took 2 gallons of water out and tested it out. I put one gallon down the gally sink and one down the bathroom sink. No leakage. I drained it back out quickly in case that sealant needs to dry more.. I didn't think about it until after I dumped in the water. It had at least 30 minutes to dry before I put the water in.

Maybe I better take off the cap off and open the valve and let it air dry inside the tank over night to be sure.

[jesilvas]

You can put on one of these clamps
http://www.summitracing.com/parts/tn...-300/overview/

[Cubey]

I got everything all assembled today. Hopefully it'll hold up. Lots of photos here:

Plan 'V' - A van dwelling blog: New holding tank installed!

[RV Wizard]

Looks good. Thanks for the update. You can now fill the tank and put a little pressure on the fitting for leak testing but I am sure you did a good job and will be leak free.

[Cubey]

If not, I did make sure that it can be disassembled without having to cut any pipes. Same with changing the valve seals later on.

I had to use one slightly non-standard part which would be a code violation if it was done on a house. The 3" 90 degree elbow between the valve and the hose hookup is meant for vents, not for drains. The one meant for drains has a more sweeping flow inside, but it's also about an inch or more wider and would have interfered with the exhaust pipe. Since it's only purpose is to drain the tank, it's not going to do any harm, especially since the inlet drain pipes are only 1-1/2 each and I don't think I'll ever have both drain pipes running at full flow capacity at the same time. Being only gray water, it shouldn't end up with any clogs like black water could when draining.

I also gave it better tolerances for vibration than the pipes did have originally. I removed and threw out short reinforced hub couplers like these (photo below) in favor of longer ones without the metal in the center, as shown in the photos in the blog post. This allows for greater tolerances in vibration so less stress is put on the pipes and tank when on a bumpy road, going over train tracks, etc.