Community Forums

wrbsab12 · 08-15-2018, 05:53 PM

Help !!!
I own a 2017 Ventana LE 4037.
Not sure what happened or why... but 2 weeks ago I found black water overflowing into my half bath sink. Mopped it up, and sure enough... happened again 3 days later.

Black tank level may have been full or approaching full.

Can anyone explain how this could occur?

Can anyone explain how the 2 systems may be somehow plumbed together ??
My impression was that they were totally independent fro one another.
I learned of a 'siphon' valve below the sink in the half bath... I checked it, took it apart to check for blockage, and it was clear. Then reassembled it.
Please confirm back if you have knowledge or guidance on this.
THANKS VERY MUCH !!

BFlinn181 · 08-15-2018, 06:17 PM

The half bath sink may very well be plumbed to the black tank, not the grey tank. Often the lavatory, or in your case, the second lavatory sink, is added to the black tank to add water for dumping purposes and to reduce the grey tank load with it taking the shower, kitchen sink, and main bath sink.

The anti-siphon valve is most likely connected to the tank flusher on the black tank. Usually, a sink will have an AAV (cheater vent) to prevent the draining of the P trap, but it is a different type of valve than an anti-siphon valve. AAV are used on drain lines, anti-siphon valves are plumbed in water lines.

If you dump all tanks, then add some food color to the sink in question, open the dump valve into a section of clear sewer pipe attached to your slinky and you'll soon discover if they are connected.

If you have an anti-siphon valve in a supply line to a tank flusher, make sure that supply valve is completely off. If it was open even a couple of drips, it could fill the black tank over time.

Skip426 · 08-15-2018, 06:21 PM

No; I can't explain how this would happen ; given the sink level compared to the toilet level , the toilet shouldn't flush , before there is any back up anywhere, and unless the 1/2 bath sink drains into the black tank there should be no connection between the grey/black systems ( except at the dump hook up).

Note ; my last fiver the bathroom sink did drain into the black tank , to add extra liquid to the black tank to carry " stuff " away, but as I stated above , with the sink 18" above the toilet water level there should be no back up, to the sink even if the toilet overflowed .
I'd contact Newmar , for a plumbing diagram and register a complaint , because what you have is a health hazard.

EDIT: I see Bob posted while I was typing , sorry for the duplication.

Quincy · 08-16-2018, 04:43 AM

I don't think the reason for piping the rear sink to the black tank is anything more than convenience or access for the guys who built the rig. I do think the shape of the black tank could have something to do with what happened.

BFlinn181 · 08-16-2018, 08:21 AM

Quote:

Originally Posted by Quincy

I don't think the reason for piping the rear sink to the black tank is anything more than convenience or access for the guys who built the rig. I do think the shape of the black tank could have something to do with what happened.

It's pretty standard to route the lavatory sink to the black tank to add water to the black tank and save the gray tank for kitchen and shower, laundry and dishwasher. No matter what the shape, it's pretty rare for the toilet not to back up before a sink that has a drain higher than the toilet.

Bill Hunt · 08-16-2018, 07:05 PM

YES! Your half bath is plumbed into the black tank. Mine was but no worries.. in Nappanee they have a special tool to help in correcting this mistake. They have a saw attached to a broom handle in order to reach in and saw off the drain line. The furnace has to be removed in order to do this.
We had to make a trip to Nappanee just to correct this.
I asked how many had been built this way. Answer was that maybe a couple had gotten through. Our coach was built the last week of July 2016.

BFlinn181 · 08-16-2018, 07:18 PM

Quote:

Originally Posted by Bill Hunt

YES! Your half bath is plumbed into the black tank. Mine was but no worries.. in Nappanee they have a special tool to help in correcting this mistake. They have a saw attached to a broom handle in order to reach in and saw off the drain line. The furnace has to be removed in order to do this.
We had to make a trip to Nappanee just to correct this.
I asked how many had been built this way. Answer was that maybe a couple had gotten through. Our coach was built the last week of July 2016.

Why is it considered a mistake? How much water goes into the black tank from a lavatory sink?