How to know when fresh water tank is full

Parlando

This forum has been great.  Thanks for sharing your expertise with new users.

I have a 320 Tab Outback, and no bathroom.  No digital readouts on this particular T@B.  I've been frustrated whenever I'm trying to make sure that my fresh water tank is full.  I fill slowly, and recently even bought a funnel and attached a 12" plastic hose for filling from fresh water containers at campsites.  I also have one of the hose shutoff connectors for when filling from a hose.  My problem has been that even when filling slowly the water begins to backup and overflow at some point.  At first I thought that this indicated that the tank was full, but it has become evident that it isn't full as the water goes down and then I can fill some more.  Today I spent almost an hour trying to fill the 11 gallon tank.  After reading some forums I finally detached the trailer from the car, and raised the trailer as high as I could.  Even then, though it worked better, it still took repeated efforts to finally feel that it was topped off.  I would really like to find a way to know when it is actually full.  And and easier way to fill.  At a campground, when topping up the tank, do I need to raise the stabilizers and then raise and lower the trailer each time i want to add water? Any suggestions would be great.  Thank you.

Sharon_is_SAM

Sounds like you have a pre-SeeLevel TaB.  The air in the tank takes longer to displace, that is why you have water backing up.  The tank is long and short and by raising the tongue you allow more air to be displaced faster.  

I think going slowly and raising the tongue as you are doing is the key to maximizing the fill.  Just keep track of how many gallons you add.  Since you don’t have a shower, and you are not concerned with a shower being interrupted, why not keep a spare jug of water to add if you suddenly run out?

ScottG

Your symptoms are consistent with poor tank ventilation. You might find this discussion useful. In particular, see my comments on page 2 regarding modifications to the vent line.

My tank filled much quicker once I got the vent line opened up. However--as you discovered--it still helps to raise the front of the trailer to keep water from backing up into that vent.

If the vent does become filled with water, I clear it by blowing hard into a short piece of tubing held against the vent hole above the filler. That usually gets me back in business for a while.

Once you establish good flow into the tank, it become clear when the tank is full. The water will just gently back up into the filler port and overflow without any sputtering, burping, or other drama

Admittedly, it's not a very well-engineered system. However, once you learn to finesse the venting and control the fill rate it works ok. 

Parlando

hi Sharon,  Thanks for your suggestions.  Yes, raising the front helps, and i go slow, but I still get the result of having the water come up the fill tank and making me think that it is full, but then it drains down and I continue.  I'm filling with a hose, so it is hard to keep track of how many gallons I've added. One of my concerns is that I read that you shouldn't use your tank below 20% because it is hard on the pump.  I'm not sure if that is true, but I've been pretty guarded about not running out.  Cheers,  Doug

Parlando

Hi Scott.  Thanks for your suggestion.  I don't have a problem drawing water up to my faucets but your comment that the symptoms are consistent with poor tank ventilation.  I was thinking the same, and even wondering if I could add a larger, more direct vent.  I had hoped that by using a clear tube attachment to the hose would leave enough air space for venting.  I think it helped a bit, but obviously didn't resolve the problem.  I looked at your picture and read your comments on the post you suggested, and I'll crawl under tomorrow and see if i have a kink in my line.  thanks!   -Doug

Bayliss

@Parlando, I stumbled upon this gadget while surfing the Internet, but have not tried it out.  I'm posting it in the event anyone is interested in it:

https://www.amazon.com/gp/product/B007NHS9M4/ref=as_li_qf_asin_il_tl?ie=UTF8&tag=knowledgeshar-20&creative=9325&linkCode=as2&creativeASIN=B007NHS9M4&linkId=eb188c6effa0de319131f48287398f65

Parlando

Thank you Bayliss..

Sharon_is_SAM

@Parlando - I have never seen anything about the pump wear and tear when used with a tank less than 20%.  There are many reports by members that the pump starts sucking air when the SeeLevel monitor reads between 15-20%.   I believe that is a function of accuracy with the sensor pad placement as well as a limitation of usefulness with our long, narrow tanks.

Parlando

Good to know.  Thank you Sharon. 

Parlando

Hi ScottG.  I finally got underneath the T@B today.  The weather has been cold! I thought that your suggestion that the vent line might be crimped was a really good idea.  Mine was, to a degree, distorted by the zip tie.  I cut the zip tie, but the vent was still distorted, perhaps by being that way so long, and perhaps by the cold weather.  I took a small hose clamp and placed it around the vent, thinking that it could round out the vent... and that did work.  I'm attaching two photos, one before, and one afterwards with the hose clamp around the vent.  We'll hope this helps.  I'll also get a small length of tubing to blow into the vent hole above the filler.  Thank you much for taking the time to give me the info.

ScottG

You're welcome, @Parlando--your tubing looked very similar to what I found on mine. Hopefully your fix will help with the filling issues! 

Dudlee

Where would I find this vent line on a 2019 320 S? Do I need to remove the bottom cover from underneath the trailer?

Parlando

Mine comes off of the front of the water tank, and then runs up towards the kitchen cabinet. ScottG posted a picture that was helpful for my 2015 T@B 320 Outback.  I'm not able to copy and paste it for you, but to see his photo go to his post on page 2:   https://tab-rv.vanillacommunity.com/discussion/5130/water-issue-read-forum-posts-still-have-issue/p2.   

He also suggested trying to "clear it by blowing hard into a short piece of tubing held against the vent hole above the filler."  And raising the front of the trailer all the way, quite high, did help.  Also Floyd67 had an interesting idea for clearing the vent on page 2:   https://tab-rv.vanillacommunity.com/discussion/5130/water-issue-read-forum-posts-still-have-issue/p2. 

good luck.  -Parlando

ScottG

Dudlee said:

Where would I find this vent line on a 2019 320 S? Do I need to remove the bottom cover from underneath the trailer?

I believe you will have to remove bottom cover. Mine is a 2015 and lacks that cover, which I think was added a year or two later.

plink50

While this may be a silly question, since I am new to this world, bear with me! I have a 2021 T@B 400 Boondock beast and wanted to make sure I did not ruin anything when overfilling the fresh water tank. I left the hose running to fill up the tank and wandered away. When I remembered, I rushed back, turned off the hose and noticed water pouring out below the filling area. I did not see any flooding inside or any issues since then. Does this beast have an overflow valve that allows such an error without causing damage to any systems? I hope!

pthomas745

@plink50,  Welcome to the Forums.  The World Of Silly Questions That Are Not Silly At All. 

Question 1:  Did you use a water pressure regulator? If No, see below.

Answer: The plumbing system in the trailer has a built in pressure relief valve.  It is The Famous Yellow Pressure Relief Valve. The trailers PEX plumbing can't handle a lot of pressure, so when you don't use a regulator, the valve will open to protect the pipes.  (This is basically what  you called an "overflow" valve...but the Yellow Valve is also used to drain the Alde tank.)

Here is a thread with a picture of what to look for. (Not exactly sure where it would be in your trailer, but it might be in the Alde compartment.)

https://tab-rv.vanillacommunity.com/discussion/9306/city-water-connection-issue

You can reset the Yellow Valve by pressing it down til it clicks shut.

If  you did use a pressure regulator, see the Answer and check the valve anyway.  If it is shut, there may be other issues.

Sharon_is_SAM

@plink50 - Regarding overfilling the 2021 fresh water tank:  I know on the 320 there is an air vent from which water may escape.  It seems to me that someone else overfilled with the same wet result.  Hopefully someone with the new 400 and Nautilus will chime in.  The excess pressure when you don’t use a regulator will trip the Alde Safety/Relief valve when you are hooked up to the Nautilus for a city water connection.

Sharon_is_SAM

@plink50 - here is a response from nuCamp from another thread:

Here's the answer from NuCamp customer service for a 320S:

"while the nautilus does warn against overfilling we have a setup to where it will not damage the tank / lines if you overfill. There is an overfill line outlet that’s located right behind the Nautilus panel itself that will spit out water when the tank is overfilling .... {extraneous text removed}.... I made sure to check with Quality Control on this as well and they say the same thing."

So, no worries!

plink50

Thank you, Folks...most helpful...and stress relieving...on to other worries...and the road ahead.

annechris

The T@B manual has warnings not to overfill the fresh water tank. I filled it until the control panel level indicated full, and then slows added a bit more with no problem. Boondocking is often water limited, so I'd like to know when the tank is completely full, without risk of breaking anything. In our old RV there was an overflow next to the fill port that water spouted out of when it was overfull, and I could easily hear when that was about to happen. Is there any such indication with a T@B? I've got a 45 lb pressure limiter on the fill hose.

Sharon_is_SAM

@annechris - I moved your post over to this existing thread.  Filling the tank on models with the Nautilus was addressed by nuCamp in my January 2021 post above.