fresh water tank 3 lines

1950 · 10-07-2022, 07:17 AM

1950 here,

I know this has been discussed before , but can someone tell me why my class c has 3 lines to vent my water tank ??? What is the purpose of 3 lines hanging down going nowhere. Thinking about redesigning this setup Yes you need 1 to act as a vent for sure but it can also bo an overflow line as well . The other 2 lines seem useless. Ok so what am i missing here, Jayco must have had a reason to install 3 vent/overflow lines . Can someone explain. When i fill Water overflows out only 1 line. When i stop or corner water flows out of this line as well , so, can i cap it off ?? the other 2 could still vent my tank? Loosing to much water going Dry Camping.

Thanks John 2021 Redhawk 24 B
Happy Camping Yall

Jagiven · 10-07-2022, 07:26 AM

At one point I recall a conversation, there was some suspicion that using multiple lines eliminates the possibility of siphoning. There has always been one for each FW tank. That really depends on how they are plumbed between the tank and the open end. I do not recall anyone every confirming this was the case. I would contact Jayco with your vin number and ask for the plumbing diagram. This will show you how it is plumbed.

Now the really question, are you sure they are all for your FW tank. Could two of them be for your low point drains for your plumbing system? The one that drains when you over fill the FW tank, is it clear or black? What color is the other two vent lines? Red and Blue? If so they are your low point drains for the plumbing distribution lines. Red, hot water line, Blue cold water line. You will have a funky Tee valve somewhere, often under the bathroom sink, you can pull and drain the pressurized lines.

Grumpy · 10-07-2022, 07:26 AM

Because when you fill it with a hose one line does not allow it to vent fast enough. They've been using 3 vents as far back as I can remember. I know our 08 was the same, not sure about or 01.

Many just added valves to all 3 and closed them once you stopped filling it, you just have to remember to open them once you get to your destination. There is also a thread in Super C, I think, where someone made a manifold that stopped the siphoning.

1950 · 10-07-2022, 08:02 AM

thankyou for your knowledge, much appreciated . All 3 lines are clear and same size . All come from top of fresh water tank. my low point drains are red and blue and are located in right rear compartment valved off. i have read about valving the 3 lines off ,and that would work until i forget to turn them on and collapse a tank. Good to know there has been 3 lines for a while. i will contact jayco and ask for a diagram of plumbing , good idea. has to be a solution.

thanks again john.

JimD · 10-07-2022, 10:44 AM

If you can route them up above tank level then they will vent just fine and NOT siphon 1/3 of your tank while driving.

I originally put valves on mine under the chassis but having to remember to open them was a pain. I ended up lengthening the hoses and routing all 3 up into my outside shower/water fill cabinet. I put valves on them but never really need to close them off. Problem solved with no need to open/close valves.

1950 · 10-07-2022, 02:07 PM

thanks Jim D , thats what im thinking . jayco sent diagrams , but not much help . but they show 3 vents just as Grumpy stated. but they donot show if they extend down in tank. if one does, it would syphon out a lot of water and i need all i can carry.

thanks everyone good info.

happy camping John

**JFlightRisk** · 10-07-2022, 04:49 PM

Quote:

Originally Posted by 1950

thanks Jim D , thats what im thinking . jayco sent diagrams , but not much help . but they show 3 vents just as Grumpy stated. but they donot show if they extend down in tank. if one does, it would syphon out a lot of water and i need all i can carry.

thanks everyone good info.

happy camping John

None of the hoses are inside the tank. They all attach to a spin-weld nipple. The "siphoning" affect is a result of shallow tanks and sloshing water. It's very common in trailers and fifth wheels too. We're in the camp of those that attached valves on the hose ends, but we don't boondock or carry a full tank when driving.

NYCANCamper · 10-08-2022, 07:52 AM

I capped two of the hoses and replaced the third hose with a longer piece and attached it to the underside of the floor so it's now higher than the tank to break the siphon. No problems since the mod.

1950 · 10-08-2022, 08:36 AM

yes i will try raising the lines up under floor good idea thanks JOHN

Learjet · 10-08-2022, 10:35 AM

anyone have a picture of the 3 vent lines coming out of the tank?

Bullitt6283 · 10-12-2022, 12:56 PM

Near as I can tell, there are three vent lines because Jayco wants to be sure you lose most of your water when making turns or driving on a crowned road.

Just kidding....

.

cherv · 10-12-2022, 01:49 PM

we have the same situation.. going to extend and raise them. photo

whowlett · 10-12-2022, 03:27 PM

I got this from another thread a while ago. Valves are from Home Depot. They turn easily so only one hand is needed.

Learjet · 10-12-2022, 03:56 PM

I don't like how low they hang....and closing those off are a problem waiting to happen....good way to blow up or collapse your tank....temperature changes, pressure changes from elevation/weather changes, forgetting to open when filling or using the system with them closed.

whowlett · 10-12-2022, 04:36 PM

Quote:

Originally Posted by Learjet

I don't like how low they hang....and closing those off are a problem waiting to happen....good way to blow up or collapse your tank....temperature changes, pressure changes from elevation/weather changes, forgetting to open when filling or using the system with them closed.

Never been a problem. Let’s see 26 gal tank * 8 pounds a gal = about 200 lbs. Pretty strong tank if you think about it. I don’t actually fill it, but maybe 1/3 full. However I have done some short trips with it near full. Like I said never had a problem. And I am not the only one who has done this.

**JFlightRisk** · 10-12-2022, 05:01 PM

Not a Class C, but did it on the two tank vents on our TT.

https://www.jaycoowners.com/forums/m...lbums1153.html

aqharoper · 10-12-2022, 05:29 PM

As mentioned this is a common problem. We have a new Seneca 37K and the water tank will only fill to 3/4 full or 55 gallons. We left out for a 800 mile trip and when we got there I only had about 10 gallons in it. 45 plus had siphoned out with no place to get water when we got there.

Looking at extending mine as well.

Insane938 · 10-13-2022, 07:16 AM

Quote:

Originally Posted by JimD

If you can route them up above tank level then they will vent just fine and NOT siphon 1/3 of your tank while driving.

I originally put valves on mine under the chassis but having to remember to open them was a pain. I ended up lengthening the hoses and routing all 3 up into my outside shower/water fill cabinet. I put valves on them but never really need to close them off. Problem solved with no need to open/close valves.

I had basically the same idea, except, I tied all the lines together, and ran just 1 line up to my water control board. Capped it off with some screen so no bugs can get in. No problems going from sea level to 9000', and no more empty tanks when we get there. (3 1/2" lines to a 3/4" vent line up. Check it out. More than enough vent.)

201822j · 10-13-2022, 07:57 AM

I merged all 3 vent lines to a single larger hose and have a shut off for the one. Yes you have to remember to deal with it but I have the water I filled with when I get to my destination

1950 · 10-13-2022, 08:36 AM

1950 Here, attached all 3 vent lines to underside floor of rv. filled tank to overflow . no more syphoning. going to make a short road trip and check it out. i can easily turn the 3 into 1 line but nowhere to raise it any higher . no compartments higher than floor Redhawk 24B ya know.

still re designing JOHN

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