Kinda makes me miss my old 2006 National Tradewinds diesel pusher that I traded in for this Redwood

Oh wait! I hear that THOR may buy them next!

We had plans for a DRV in the near future. But I've checked around on the blogs and there are some concerns there as well. I would have to think that maybe, just maybe, there would be less complaints. But to put that in perspective, how many DRV's are actually out there? The are pretty expensive. Still, if we had been able to attend the Redwood Rally, we had plans to slip over to the DRV factory just to see if it was ANY better. We could not go this year as we have to deal with a crappy roof installation. Another story you can read about in other postings here...

BTW...Nice paint on your rig! I like those colors.

Hi everyone. I have a confusing situation with my holding tanks. I have a 2018 3921GK with two gray tanks and one black tank. Originally I thought my InCommand system was not working properly for gray holding tank 1 because it never showed and gray water in the tank. I figured it wasn’t reading the sensor. Meanwhile I was noticing that the gray holding tank 2 was filling awfully fast and I was dumping it ever other day. I just purchased a new sewer hose with a clear elbow and decided to investigate the problem. I ran a constant flow of water into my kitchen sink and went and opened the gray 1 valve. No water flowed from the tank. It seems that all of my sinks and showers are plumbed into gray tank 2.

I can think of two possible possibility:

1. Someone at the factory made a mistake and plumbed everything into gray tank 2.

2. The system is designed to spill over into gray tank 1 after gray 2 becomes filled.

There are two physical gray tank pulls in my utility cabinet and there are two gray tanks configured in my InCommand System. I have never had water come out of the tank labeled gray tank 1. My coach literature indicates a gray tank capacity of 88 gallons. There is no way I’m holding anywhere near that in my gray 2 tank. Anyone else experiencing this? I guess I might have to end up taking things apart to understand the mystery of gray tank 1????

The probability of #1 is extremely low, the probably of #2 is 0. Don't waste your time letting the Dealer park it on the lot and stare at it for a couple of months. Redwood has drawings and you should be able to get a copy through customer service or the Dealer. With Keystone in the mix it won't be easy, but I think once you have them you'll see what Engineering did. I would blame them before production. Some had tanks that did nothing but serve the W/D on some floor plans. Some had washers that drained into the black.

Our Montana had the typical two Gray tanks, one for the Bathroom, the other for the Kitchen Sink, but to use the washer we added (pre-plumbed from the Factory) you had to be connected to sewer as it drained directly into the outlet pipe.
With our current '16 MB, they Gray Tank handles the bathroom sinks, shower, and washer. While the Galley handles the Kitchen Sink and Dishwasher if so equiped.

Our Montana had the typical two Gray tanks, one for the Bathroom, the other for the Kitchen Sink, but to use the washer we added (pre-plumbed from the Factory) you had to be connected to sewer as it drained directly into the outlet pipe.
With our current '16 MB, they Gray Tank handles the bathroom sinks, shower, and washer. While the Galley handles the Kitchen Sink and Dishwasher if so equipped.

I had one of those - a 3400. I was OK with the washer being direct to sewer but if you didn't know that up front it could make a mess. The nicest people bought it from us and I got a call a week later as to why the kitchen sink was plugged up - I forget to tell him about the drain valve above the wheels on the street side.

we had that problem, the washer (which we don't own) went to one holding tank with the bathroom sink, everything else to the other tank which was always filling quickly. Dave rerouted the shower to the bathroom sink tank, so the kitchen is in one tank and the bathroom goes to the other. He said it was easy to do in the basement.

For what it's worth, my thoughts based on the multiple "holding tank mystery" threads I've read and time I've spent trying to figure my rig out is don't bother asking Redwood CS, they don't talk to engineering never mind production. My rig is my rig and I work with what I've got, and am really happy with it even with it's flaws. Luckily I like working on my rig and figuring things out but still I have the basics to work with.

In my 2015-38FL through multiple tests I've confirmed my holding tank hold water and through an upgraded monitor system and a back fill adapter each works just fine and holds fluid as advertised. Start by checking the important boxes for sure.

Saying that, I basically deal with both tanks, plumbed separately, by using an external shut off valve. Having the external valve closed and both internal valves open, water can freely flow between both tanks letting gravity work for me. HUGE NOTE HERE: Some models have their 2 grey tanks at different levels and this won't work!!!!!!

As Oriana says, the external valve closed and internal valves open let's water go back and forth. I don't even try at this point to contemplate why the engineering team decided not to tie them together, but alas they didn't and I can work around it so what ever blah blah blah......

Note if you do install a monitor system, like the iSeries I use, I find it helpful to calibrate one grey tank to cool weather (50F-60F) and one to hot weather (80F-90F) so I can during normal use take the average reading to get a exact sense of the holding tank levels.

Ken, you are correct, with MB being one model with the tanks at different levels. Our Galley tank is in the belly above the axles, while our Gray is in the Front Drop-down area. So if we left both valves open with the outlet closed all the Galley/Kitchen water would fill up the Bathroom Gray.

Thanks for all the replies and possible explanations. I'm scheduled for a dealer visit in December (weather dependent) and hopefully they'll figure it out. Bottom line everything works properly except I have one gray tank that never gets water in it. I have a washer and dryer (dealer installed) that seems to drain into the gray tank. No dishwasher in my coach. Gotta love a mystery.

I have a 2014 RE, and the shower drains into the gray water tank, not the galley tnk as some have mentioned.

I still haven't had this fixed as I didn't want to tow my rig to the dealer until warmer weather arrives. I just drain my tank frequently. My two grey tanks are not labeled as "galley" or anything other than "Grey Tank 1" and "Gray Tank 2" so I don't know exactly which physical location the water is going into. I only know that "Gray Tank 2" is the only tank that accumulates grey water. Nothing had ever come out of "Grey Tank 1".

What a lot of us have done to even out the grey tanks is add a Valterra gate valve at the outlet under the coach. That way you can close that valve and open both grey valves and the two tanks will equalize Might be worth a try in your problem to get more capacity.

I would need to check to see if my grey tanks on on the same level in order for this to work. I have a 3921GK model. Would there be any concern about the grey water going back into the black tank from a valve that doesn't seal 100%?

I know the earlier GKs were the same layout as my RL. The grey tanks are side by side and the black is,above them. I've been doing it this way to equalize th greys for over 5 years.