Fresh water won't fill more than 2/3

[Morich]

Originally Posted by dkoldman

This is crazy. With all of the info I have read thus far it makes me think of one thing that I have seen do similar. Maybe it creates an idea for someone.

I have Saltwater tank, when I drain I using a siphon pump. I am trying to visualize if I have siphon in fixed position where 1/2 tank provides enough pressure head restart the siphoning. The pressure coming out my Siphon tube is function of weight of water. Have you eyeballed exactly with overflow come out of tank?

In my tank, I can see the water tanks water level and overflow at the same time. It would be impossible for water to come out that overflow unless the tank water lever was raise to level of the input.

You have caused me to reconsider and admit mistakes!

I'm not following what you are saying about the siphon but I have to say I left out one big thing about building pressure! There was a blank in my thinking and I left off the overflow!

With the overflow added, there is no way to build pressure in the tank as air and finally water will go out the overflow and longer before forcing it's way up and out the much higher vent and gravity fill tubes!

That makes my ideas totally bogus, so back to not knowing how it happens!

[dougb]

Both tubes backflow but the external intake tube shoots water out with force like a water hose at your house on full. Very strong back pressure. The whole thing is very weird.

[dkoldman]

Originally Posted by Morich

You have caused me to reconsider and admit mistakes!

I'm not following what you are saying about the siphon but I have to say I left out one big thing about building pressure! There was a blank in my thinking and I left off the overflow!
Attachment 189447
With the overflow added, there is no way to build pressure in the tank as air and finally water will go out the overflow and longer before forcing it's way up and out the much higher vent and gravity fill tubes!

That makes my ideas totally bogus, so back to not knowing how it happens!

This is why I say this is crazy, need to eyeball the plumbing, pictures are needed. I believe what is happening and if true it is NOT built by design because per design this phenom would be impossible.

I use the Siphon reference as the manner how I extract saltwater from the aquarium. I have a valve on one end that I can turn the flow on/off. It is emptying due to flow started by outbound air flow, but if I turn it off the pressure sustains. Really slick. Now in this application there could be something like check valve in the line and pressure in the line maintains based on the height or location referential of the tank.

Until I see a actual real life picture of the overflow line on the tank, all bets are off. This is where I stand around the Blackjack table and watch keeping my money in my pocket

[dougb]

Yes its crazy. But I am determined to find a solution so that I can have a full fresh water tank when heading out. When boondocking it is essential as you know. Thanks again for your ideas and ramblings.

[Morich]

As the drawings show the overflow should just be a simple pipe out of the tank and an elbow to turn it down and out of an open pipe underneath.
With the gravity fill and vents both higher than the tank top, it really should make any over flow go out that pipe way before going higher and out the gravity fill???
Mud daubers filling the end of the overflow pie might stopper it but water seems like it would wet them enough to move the clog out!

Maybe worth the time to crawl under and shoot water up the overflow to make certain it is open and clear?

But I admit to getting rid of all my fish as it became a job to fuss with the water. Once it overflowed and the neighbor was watching with no idea what to do, I went with keeping the RV for trips and losing the fish!

[carpedatum]

I have the same problem, only with a travel trailer a Minnie 2327TB. My water gauge, the tank level gauge, and the gauge on the pump truck at tha Balloon Fiesta all agree. Water starts flying back out at about 2/3 full.

The tank on the Minnie is completely hidden and I haven’t yet got up the nerve to cut my way in for a look, but I have a crude workaround.

I use https://www.recpro.com/rv-water-fill-secure/ and a water meter, When the water starts coming out and the meter reads less than full, I just keep on filling. While this dumps a lot of water on the ground, the water fill gadget helps keep the pressure on. Eventually the hissing noise from the vent changes, some water spits out of it, and normal flow resumes until the tank is actually full.

I have snaked both lines and detected no issues. Getting in there for a real look will be hard work. Please do post back if you figure it out. I will if I do.

[wahoonc]

Originally Posted by carpedatum

I have the same problem, only with a travel trailer a Minnie 2327TB. My water gauge, the tank level gauge, and the gauge on the pump truck at tha Balloon Fiesta all agree. Water starts flying back out at about 2/3 full.

The tank on the Minnie is completely hidden and I haven’t yet got up the nerve to cut my way in for a look, but I have a crude workaround.

I use https://www.recpro.com/rv-water-fill-secure/ and a water meter, When the water starts coming out and the meter reads less than full, I just keep on filling. While this dumps a lot of water on the ground, the water fill gadget helps keep the pressure on. Eventually the hissing noise from the vent changes, some water spits out of it, and normal flow resumes until the tank is actually full.

I have snaked both lines and detected no issues. Getting in there for a real look will be hard work. Please do post back if you figure it out. I will if I do.

Get ahold of an endo camera. They are relatively inexpensive and small enough to run down a water line or even a vent line to see what is going on.

This is the one I have it has proven invaluable for getting into places on the RV to see what is going on with minimal destruction for access.

Aaron

[Ray,IN]

This mini camera for a cell phone should fit.

[racer4]

Originally Posted by carpedatum

... snip... Eventually the hissing noise from the vent changes, some water spits out of it, and normal flow resumes until the tank is actually full. ...snip

Where is the vent hose? I can't find it on a Minnie 2327TB.

I also have a Minnie 2327TB, and the fresh water tank overflows at about 24 gallons with a 60 gallon tank. I also use a water meter to count gallons and use a similar water fill hose.

Can you point me to the vent hose?

[dougb]

Got the tank full!!! Less water pressure when filling did the trick. Thanks for all the help.

[Jeepien]

The physics of the situation are consistent with a vent tube that is extended inside the tank so that it reaches the surface of the water in the tank. Adding water would then force water though the tube but not be able to expel the air and raise the level to full.

[Morich]

Originally Posted by Jeepien

The physics of the situation are consistent with a vent tube that is extended inside the tank so that it reaches the surface of the water in the tank. Adding water would then force water though the tube but not be able to expel the air and raise the level to full.

This was my first thought as well!
However, I missed thinking about the overflow tube out the top of the tank. If air can go out the overflow, why is pressure possible to build enough to force water up the vent and fill tubes?
I had to back off and rethink but I do not yet see any way it can do this!

I'm not yet seeing an explanation!

On the question of where to find the vent, I don't know this trailer but it is common for the vent to be a small opening alongside the gravity fill port.

For a follow up question for the OP? Were you able to verify the overflow tube is open and not clogged or restricted in some way?

[Englishjay]

one thing that can make this happen is if the vent pipe coming into the tank extends into the tank meaning it only vents up to that level.
This can also be the reason why a tank can syphon out after being full.

If you have a gravity fill point open when filling that can help - as long as the internal pipework doesn't extend down into the tank as well.

you maybe able to loosen that fitting, pull the hose out so it doesn't extend into the tank and re-tighten the fitting...

worth a try

[Morich]

Originally Posted by Englishjay

one thing that can make this happen is if the vent pipe coming into the tank extends into the tank meaning it only vents up to that level.
This can also be the reason why a tank can syphon out after being full.

If you have a gravity fill point open when filling that can help - as long as the internal pipework doesn't extend down into the tank as well.

you maybe able to loosen that fitting, pull the hose out so it doesn't extend into the tank and re-tighten the fitting...

worth a try

I first thought this was true but if you look at the posts above, I had made the mistake of forgetting about the overflow on the top of the tank. air doesn't have to only go out the vent but can also go out the overflow!
Thinking of there also being a pipe out the top of the tank for overflow, I now wonder why they bother with the extra step of venting???

[powercat_ras]

I had the same issue with my 2015 Vista 27N, where the location on the far end of the tank on the driver's side would pretty much guarantee I would lose many gallons of water driving from where I filled it full to where I was boondocking.

For those times when I want to arrive at get my boondocking site still totally full, I added a ball valve in the overflow, next to the drain valve, so I can fill, close that new overflow valve, and drive to where I'm going without losing part of the water on the way.

IF YOU DO THIS BE SURE TO USE ONLY WHEN ABSOLUTELY NEEDED. IT CREATES A RISK OF BURSTING OR COLLAPSING YOUR WATER TANK IF NOT PROPERLY USED.

I NEVER close it EXCEPT when driving to my boondocking spot. I open it once I am parked and leveled. I have a tag I place next to the water pump switch reminding me to open the valve, when I use it.

You need that valve open otherwise to vent the tank so you can safely fill it and/or draw water out of it without risk of collapsing or bursting the tank.

[Morich]

Too much confusion creeping in as there are two totally different RV being talked! There is the 2015 Vista 27N but there is also the 2019 Adventurer 27N which the OP asked about.
They are not at all the same on the fresh water tanks, so a solution for Vista is not going to be correct for the Adventurer!
The Vista has a pump on the passenger side, while the Adventurer has it behind the wet bay nearer the driver's side.

[powercat_ras]

Originally Posted by Morich

Too much confusion creeping in as there are two totally different RV being talked! There is the 2015 Vista 27N but there is also the 2019 Adventurer 27N which the OP asked about.
They are not at all the same on the fresh water tanks, so a solution for Vista is not going to be correct for the Adventurer!
The Vista has a pump on the passenger side, while the Adventurer has it behind the wet bay nearer the driver's side.

I'm 99% sure they ARE the same or I would not have given the advice I did.

The Adventurer 27N is just a re-branded Vista LX 27N with a few minor changes to justify the $ 30K higher price. The water tank, black tank, and grey tank are identical as is the floor plan. This all happened a few years ago when Winnebago rebranded Vista LX and re-introduced the Adventurer brand, but just re-using all the designs for Vista LX with a few minor improvements.

Exactly the same Ford F53 chassis and wheelbase. Has full body paint (that was an option not standard on Vista 27N), one addl bedroom window, 50A instead of 30A electric power, 2 roof AC instead of 1, better backsplashes in bath and kit, and a power shade in the front window. Some of the abover changes actually appeared when Vista 27N was re-branded Vista LX 27N.

Note that Winnebago no longer makes the 27N model so Morich might have been referring to the current short wheelbase Adventurer which is NOT the same as it is NOT a 27N, and with a different floorplan DOES likely have different fresh, grey, and black tank design.

The issue with the 27N is that it has a long and wide tank with not a lot of depth other than a deeper section on one side where the water connection for the pump is. With the overflow / vent right on the far front driver's side edge of the water tank it takes only a very small change in coach angle when driving to start water flow down the overflow then the siphon effect kicks in. Being a large diameter 3/4" overflow you can lose a lot of water in a short drive. The loss stops at about 2/3 full if you leave everything as it left the factory.

Another way that I stopped the problem before I installed the valve I mentioned in my prior post was by putting an un-inflated balloon over the end of the overflow tube where it comes thru the bace of the compartment. This has the advantage of being risk free as the balloon will break if you are filling and the tank starts to overflow. It has the disadvantage that the balloon does not last and has to be frequently replaced which is a PITA.

[Morich]

When the OP reports they have a problem with a 2019 Adventurer 27N, I have to assume they mean a WFF27N and that is what I feel we need to talk about.

If somebody has a problem with a 2015 Vista WFE27N, I don't think that adds much to solving the problem for the OP!

[dkoldman]

Originally Posted by dougb

Got the tank full!!! Less water pressure when filling did the trick. Thanks for all the help.

Any idea of actual water pressure and what you reduced it too?

The effect you describe reminds me of when I put 2 oz of concentrated week control in a 1 gallon jug. If I take the water at high pressure I can never fill that jug, most will come back out. In your case the hose is sealed so it may be doing the same thing just out of your overflow.

I have a small portable valve I use between hose & port to fill tank. I believe it caps at 45psi (or close to that)

Glad you got it resolved (or a fix)

[powercat_ras]

The drawings posted in post #38 show that the shape and size of the 64 gallon fresh water tank and the location of the overflow on the top of the tank is in exactly the same as on the 27N 2015 and 27N 2019 water tank. Winnebago is clearly using the same rotocast water tank mold for all model years of 27N. The drawings indicate that the fittings being installed for the gravity fill and overflow on the top of the tank are in the same position both years.

Yes, they moved the fitting for the water pump but this is not related to the fact that water gets lost out the overflow and its drain tube when you start driving with the tank full.

I explained in prior posts why this particular tank has the issue and how to address it in several ways. To add, one of the reasons a lot of water can be lost quickly when driving is the fact that the type of gravity fill door Winnebago uses on the 27N is not totally air tight when closed, so this gives a 2nd air source to the fresh water tank so that when driving and water starts flowing out the overflow tube and drain the tank gets air to replace the water getting lost thru the gravity fill door and its tube leading to the water tank.

Morich, thanks for your interest in sharing your vast knowlege and experience with all of us and I try to do the same. I'm sharing my vast experience with this particular model of Winnebago, the 27N that I have owned since new, over 9 years. I'm not usually down this level of detail on other Winnebagos that I have no personal experience with.