Fresh water tank issue

8thdwarf · 06-03-2021, 08:13 PM

Purchase 2021 Redhawk 23C 25'... love it... took it out for two shake down runs, one over night no ele, had water... 2nd, 2 nights full hook ups.... running across country now and fresh water tank emptied after fill up... filled up 18 miles from camp site... when I got to site there was MAYBE 5 gallons left in tank.... design flaw? Trip to local stop 'n rob and filled tank, again... pinched off overflow drains until I got to camp site.... seems ok...🙄🤔🤔

AZMarine · 06-03-2021, 09:20 PM

Lots of post & fixes for this issue on the site. Note: Most tanks are laid across the frame rails, not along them. That said:
1) "If" overflow line on right side of camper, it will be on "down side" of the road while traveling.
2) Water sloshing around on every turn, etc. & again tank leaning most of time toward overflow line side. This causes the water to be forced out of the overflow lines. There is also some who say there is a siphoning action when driving, but personally, I thin k the two mentioned causes are more the root causes.

Most fixes involve either pinching off the lines (like you did) or installing some cut-off valves on the lines. I did the cut-off valves & mounted to the skirt running around the camper. That way I could open them while filling & use, & close them while traveling.

**JFlightRisk** · 06-03-2021, 09:22 PM

It's very common. Several threads on the subject here. The fresh water tanks are long, wide, and very shallow so the remedies vary to what works for your rig. Some redirect the overflow hose a little higher, some plug the end or clamp it closed until they arrive at their destination, and others, like me, have installed 1/4 turn valves on the end of the hoses (we have two tanks and overflows).

The latter fix requires opening the valve, or removing the plug to fill the tank, and use the water pump so it vents properly.

8thdwarf · 06-03-2021, 11:28 PM

Thanks for all the insights.... it's as I thought... shallow tank with water moving on grades or turns... I would have thought the designers/ engineers would have addresses this issue... they must have been lower academically on their graduation class.....

**JFlightRisk** · 06-04-2021, 12:04 AM

They used to put tanks above the flooring, like under beds. The demand for interior storage was one reason to get them out of the inside, the ability to add an additional tank like on ours, and a lower center of gravity. That caused them to design shallower tanks to fit up into the frame.

dbahn · 06-04-2021, 04:57 AM

The tank is shallow and flat. Imagine filling a bathtub with water in the bed of a truck and then driving up and down hills and around corners, all while accelerating and braking. Putting a piece of plywood with 3 holes in it over the tub might stop some of the water loss, especially as the water level gets low.

On the other hand, keeping the tub flat and motionless could only "siphon" a small amount of water out before air enters the siphon tube and the action stops, so I agree that siphoning isn't the problem.

There are a lot of suggestions here and on other sites about how to manage the water loss. Here's one that I'm working on.

Grumpy · 06-04-2021, 06:33 AM

Just remember if you put valves on the overflow(s) that you open them when filling your tank or when running the pump...

dbahn · 06-04-2021, 07:14 AM

Quote:

Originally Posted by Grumpy

Just remember if you put valves on the overflow(s) that you open them when filling your tank or when running the pump...

The nice thing about stoppers instead of valves is that one of them will just pop out and be lost if you accidentally leave them in while filling. (Carry a few spares.) That doesn't happen with on/off valves.

I think the check valve installed between the stopper and the tank will allow air into the tank to equalize with the atmospheric pressure, so if you forget to remove the stopper while running the pump it "should" prevent collapse of the tank if you create a vacuum in the tank from the pump.

repeach · 06-04-2021, 11:55 AM

When I added my extra water tank I rerouted the breather/ vent lines. I spun them so they point forward, then clipped them as high as I could (underside of house floor), then routed them back down. I have not had a siphon problem since.

rgolding · 06-09-2021, 06:31 AM

We use a single shutoff valve on the 3 vents, after tying them together, and running the outflow across the unit to where the fill is. Like Grumpy says, we just open it before use. This allows us to carry maximum water and arrive at our destination with the water we expected to have.

8thdwarf · 06-09-2021, 06:48 PM

Yup.... thinking that's gota be the next step after landing from this trip.... thanks for the feedback....

dbahn · 06-09-2021, 07:12 PM

Quote:

Originally Posted by rgolding

We use a single shutoff valve on the 3 vents, after tying them together, and running the outflow across the unit to where the fill is. Like Grumpy says, we just open it before use. This allows us to carry maximum water and arrive at our destination with the water we expected to have.

But, but, but . . .

Why are there three overflow vents instead of just one? My understanding is that one vent is inadequate if you happen to fill with a high pressure hose and don't have a regulator attached to your fill hose. If you combine three vents into one (for convenience) you've effectively reduced the venting capacity back to one vent, which could cause the expensive damage that the three tube configuration was designed to prevent. That's why I think putting stoppers on two of the vents is a MUCH safer way to prevent spillage through them. Worst case scenario - the stopper or stoppers get blown out of the tube and you have the "stock" configuration, which can be re-improved by simply replacing the lost stoppers.

pconroy · 06-10-2021, 11:29 AM

Quote:

Originally Posted by dbahn

But, but, but . . .

Why are there three overflow vents instead of just one?

Every new engineer who joins the Jayco team eventually asks that question.
At that point all of the other, older engineers turn and give the kid a look that says...

"Because, we've always done it that way."

Weatherman1 · 06-12-2021, 12:24 PM

Problem with check valves is you lose the overflow capability of the "overflow" tubes and will pressurize the tank and probably cause something to let go!

dbahn · 06-12-2021, 01:11 PM

Quote:

Originally Posted by Weatherman1

Problem with check valves is you lose the overflow capability of the "overflow" tubes and will pressurize the tank and probably cause something to let go!

That's what the stoppers are for - to prevent pressurization of the tank.

I measured the amount of pressure needed to pop them out and it only takes 5 to 10 psi, depending a bit on how hard you push them in, but that's well under the 40 psi filling pressures. So with a pressurized tank you simply lose one or more rubber stoppers, which are cheap and easy to replace. The check valve is to prevent a vacuum from forming in the tank as water is pumped out from it with the stoppers still in place.

Weatherman1 · 06-12-2021, 02:00 PM

Check valves only work in one direction

Reverend D · 06-12-2021, 02:32 PM

[QUOTE=8thdwarf;969249]Purchase 2021 Redhawk 23C 25'... love it... took it out for two shake down runs, one over night no ele, had water... 2nd, 2 nights full hook ups.... running across country now and fresh water tank emptied after fill up... filled up 18 miles from camp site... when I got to site there was MAYBE 5 gallons left in tank.... design flaw? Trip to local stop 'n rob and filled tank, again... pinched off overflow drains until I got to camp site.... seems ok...🙄🤔🤔[I have a 2018 Greyhawk Class C Motorhome and had the same problem. I put some drain caps on all three fresh water lines and cap them off on every trip. I just make sure to take off the caps when I'm filling the tanks. But after the tanks are full, I cap them off again. Gotta have water going across the desert. Haven't had any problems yet and it's been over a year now.]

dbahn · 06-12-2021, 02:38 PM

Quote:

Originally Posted by Weatherman1

Check valves only work in one direction

That's the whole point. The check valve will let air IN to prevent a vacuum in the tank but will not let water OUT with spillage or "siphoning". So it only even operates in response to a vacuum in the tank, which is created by running the pump with the stoppers in place. But it's easy to remove the stopper for filling and then the check valve doesn't do anything, i.e. it's only used if you forget to remove the stopper.

Weatherman1 · 06-12-2021, 02:51 PM

Ok so if it lets air [in] to break a vacuum then how does it relive air when your filling?
That would be the air going [out] instead of [in].
I'm not trying to be difficult. Just trying to indicate that a check valve will work one way.

Bullitt6283 · 06-12-2021, 04:14 PM

Okay, here's the deal...

If you're gonna block off those overflows to prevent water loss while traveling, you gotta remember to unblock them

when you're filling the tank
when you're drawing water out of the tank.

If you're afraid you might not remember to do these things, then you gotta install some valves to perform these functions automatically.

1. A pressure relief valve to prevent over-pressuring the tank
2. A vacuum relief valve to prevent pulling a vacuum on the tank.

These devices exist, just gotta find them. I'm working on it.
.

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