How does the auxiliary water tank work?

[ace85340]

I've read through the manual which seems mostly outdated for my model and I couldn't find any mention of how the aux water tank works.
I also asked the dealer during the PDI and they didn't know anything about it.

I see a connector near the normal water inlent that is labeled aux tank but I dont know if that needs to be filled separately or how you monitor the level of it or use the water in it.

[trueweb]

This is a good question and I still don't understand after having it explained to me twice by the dealer. Apparently it will fill and not show on your gauge, however your pump can draw down both the main and auxiliary tank. There is a separate fill inlet on the Nautilus for the Aux with appears to need pressure although the main tank can be filled by city pressure or by drawing from a water container with the on-board pump. I'd like to hear the official explanation as well, perhaps a drawing/diagram would help too.

[GDRV Missy]

Good Morning,

The Aux tank fill point is at the convenience center as suggested and then is monitored and connected to the fresh tank and is only in use when on the Dry Camping setting with the water pump on.

Missy

[ace85340]

Good Morning,

The Aux tank fill point is at the convenience center as suggested and then is monitored and connected to the fresh tank and is only in use when on the Dry Camping setting with the water pump on.

Missy

Thank you Missy, could you clarify a little more? Does the pump pull from the aux tank before or after the main tank? Is it direct or does it pump from the aux tank into the main tank and then to the fixtures?
I'm trying to imagine how the plumbing for this would work.

Thanks
Is there a separate drain for the aux tank or does it need to be emptied with the pump?

[trueweb]

I have the same questions and wonder how the plumbing works as well. Additionally, do the gauges indicate the fill level in both tanks combined? I believe there is only one indicator for fresh water.

[GDRV Missy]

Hi,
This is what I found out from the regional service managers here..... There is a separate drain on the aux tank, it will also drain by opening the drain valve on the main fresh tank, the 2 are plumbed together.
Missy

[rcastorena]

If the two tanks are plumbed together, what's the point of the aux fresh water fill point?

[rcastorena]

I have a 2018 Momentum 349M with two separate fresh tanks and two separate fill points. I fill my main tank first until water comes out of the overflow. Then I fill the secondary tank until it comes out of it's overflow. I have a cheap little water flow meter that measures how many gallons I have used and according to it, I'm only adding another 5 or 6 gallons to the auxiliary tank after the first tank is full. I've tried this even after completely draining both tanks and it's the same. Such a mysterious system. Why is it so hard to have someone from GD explain this? A simple plumbing diagram would be awesome!

[elkaholic]

Actually the system is pretty simple. There is an equalizing line plumbed into the bottom of both tanks. When you fill (or drain) one, you are essentially filling (or draining) both. The difference is that you can fill the tanks slightly faster than they can equalize.


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[We2RV2]

I feel like the name says it all, it's an aux tank. It should be used as a spare, a warning that your low on your main tank and you have to switch to your aux tank letting you know you only have 40 gallons left.
The simple fix is to add a valve between the two tanks. You can chose to not fill your aux tank if your only going for a short trip and rely on the 117 gallons or less if you chose. If your going for a longer stay fill the aux by either using your power fill or the aux fill. If you use the power fill wait till the aux starts venting water then close the valve and continue filling your main tank, at this point both tanks are 100%.
If you run out of main tank simply open the aux valve and your pump can consume from the aux now .
Seams like GD just forgot the valve. They both have vents,they both have fill points.
Just add the valve with a cable handle or use an electric valve .