general question about filling that fresh tank....

[JKyle]

I have filled the fresh tank several times and have experienced the annoying vortex that eventually causes the overflow siphon, eventually leaving it nearly empty, then start again...slow, slow, very slow.

After reading a recent post here about water leakage inside the enclosed underbelly, it leaves me asking the question:

Since I have experience fresh tank overflow, does that mean I have now exposed my underbelly/insulation with water? Does that mean I have potential problems growing in the enclosed area or do they build knowing the fresh overflow might actually overflow and leave the area clear of build material that could become damaged by water?

[JFlightRisk]

If the overflow is below the bottom of the underbelly, it should be ok. The wind wouldn't draw the water if it was above the bottom. Our underside isn't covered up, so I added a pair of 1/4 turn valves. We have two tanks.

[Kevin Cooper]

There are several past posts on how to fix the issue. I have thought about the issue and come to a conclusion to stop the excessive draining. At the highest point of the overflow hose above the tank, cut the hose, install a tee fitting, and put a few inches pointing up. This will allow water to overflow when it is supposed to, and prevent siphon from occuring without shut off valve that can be forgotten, or unknown by a new owner.
This is just my opinion

[us71na]

Originally Posted by Kevin Cooper

There are several past posts on how to fix the issue. I have thought about the issue and come to a conclusion to stop the excessive draining. At the highest point of the overflow hose above the tank, cut the hose, install a tee fitting, and put a few inches pointing up. This will allow water to overflow when it is supposed to, and prevent siphon from occuring without shut off valve that can be forgotten, or unknown by a new owner.
This is just my opinion

This is the best way to stop the siphoning!

[Kevin Cooper]

Originally Posted by us71na

This is the best way to stop the siphoning!

Is it the best? I do not know. I’ve seen a manifold of plumbing parts the works, a back flow preventer installed like on black tank flush, read a few more that I do not remember.
Will it work? If air is let into a siphon at a high spot, water flow will cease.

[JKyle]

Originally Posted by Kevin Cooper

There are several past posts on how to fix the issue. I have thought about the issue and come to a conclusion to stop the excessive draining. At the highest point of the overflow hose above the tank, cut the hose, install a tee fitting, and put a few inches pointing up. This will allow water to overflow when it is supposed to, and prevent siphon from occuring without shut off valve that can be forgotten, or unknown by a new owner.
This is just my opinion

I have approximately 6" portion of overflow hose poking out from my underbelly from my fresh tank. This wouldn't work for me, would it?

[Kevin Cooper]

Originally Posted by JKyle

I have approximately 6" portion of overflow hose poking out from my underbelly from my fresh tank. This wouldn't work for me, would it?

Judy,
You have to have access to where the hoses connect to the tank at the top. The tee needs to be at the top of the bend from up to down.

[TaftCoach]

I solved it this summer by not try to fill every gallon every time and having my DW checking the gauge as we filled. At the first light flicker of full we stopped filling. We never ran out of water and never overflowed. It was a little more work but blowing out a tank by not shutting a valve is a vacation killer worse than the siphon.

[Kevin Cooper]

Originally Posted by TaftCoach

I solved it this summer by not try to fill every gallon every time and having my DW checking the gauge as we filled. At the first light flicker of full we stopped filling. We never ran out of water and never overflowed. It was a little more work but blowing out a tank by not shutting a valve is a vacation killer worse than the siphon.

So have claimed that their tank starts to siphon and pretty much drains 3/4 of their tank. I do not believe that this can actually happen. The tubes would have to go clear down to where the water level is that they’re saying that it goes to. You’re solution is the best you don’t wanna travel with a full tank anyway.

[Camper_bob]

Originally Posted by Kevin Cooper

So have claimed that their tank starts to siphon and pretty much drains 3/4 of their tank. I do not believe that this can actually happen. The tubes would have to go clear down to where the water level is that they’re saying that it goes to. You’re solution is the best you don’t wanna travel with a full tank anyway.

I think it depends largely on the shape of the tank.

If the tank is wide/long and flat, you'll get more volume to slosh out. My tank actually has 3x overflow/vent lines. One of them is very near the rear of the tank. That means it's easy to lose water under acceleration, and since it's a shallow tank, I'll lose even more. The water sloshes back against that last hose, leaving the front two open to let in air.

I agree that there's little chance of completely emptying the tank, but it can conceivably get VERY low. Low enough to be effectively empty from a practical standpoint. A "deeper" tank would be less susceptible to this action in my estimation.

JKyle, to answer your original question: it's unlikely you have water leaking into the underbelly. It is possible, but not likely. Your overflow/vent hoses are one piece from where they enter the tank to where you can see them outside the underbelly. So there could be a leak in that hose, and allow sloshing water to escape the system, but I would think you'd be able to tell relatively easily if that were happening?

If you have multiple vents in one tank, you are more likely to lose more water from the sloshing as I described above.

Personally I have 1/2 turn valves on 2 of my 3 vent/overflow lines, and I will most often leave those two valves closed unless I'm filling the tank. This leaves one completely open, which has proven adequate for us for normal circumstances. While I do lose some water from sloshing, it's not so bad.

I made a tactical error and put those valves in the ends of the existing hoses. So now I have to lay on the ground to reach up underneath the camper to open/close them. If I were thinking practically, I would have extended them and mounted the valves somewhere more easily accessible...

Really, if I were thinking, I would have installed a manifold from the very beginning. Then I would lose no water, and the whole system would be completely "passive". I have plenty of space to do it too. Just never got around to it because we don't lose that much water with my method...

[Doxie Campers]

We are new (<4 mos) to Jayco, have a 2024 Jayhawk 30Z. Just got back from our 1st long trip where we experienced an inability to keep much water in the tank. We like to fill at least 1/3 so we are able to flush & wash when we need to on the road but found that by the time we got to our 1st stop, tank read "nearly empty". When we took it in to the dealership we learned this is due to the siphoning effect & the shape of the tank. Our dealer will fix by adding a loop of pipe. They've successfully solved this for "many" customers & say they've reported to Jayco over the years but no change by Jayco. So my question for this group: have any owners reported this issue to Jayco? Seems like if it's as common as it seems to be then they should just fix it before it's delivered to dealers! Thoughts?

[JKyle]

Originally Posted by Kevin Cooper

Judy,
You have to have access to where the hoses connect to the tank at the top. The tee needs to be at the top of the bend from up to down.

My tanks are completely hidden.
That’s okay. I’ll just keep doing ‘painfully slow’ fill method. I don’t travel with water, so I don’t need to worry about water siphoning on the road.

Before I realized I needed to fill really slow, I’d get the tank to 3/4, if I stopped a few times, but try to push it and it’d siphon almost every bit out of the tank.

It’s annoying, but at least it’s not officially ’broken.’

[Jolvi]

So maybe someone can explain as to why and when they decided to overflow out the bottom wit a loop at the top. I noticed on freshwater fill there instill a vent on the outside and nothing connected like on other RV'S I have owned.

[Camper_bob]

Originally Posted by Jolvi

So maybe someone can explain as to why and when they decided to overflow out the bottom wit a loop at the top. I noticed on freshwater fill there instill a vent on the outside and nothing connected like on other RV'S I have owned.

This can't work, because ... physics.

There has to be a vent in the top of the tank somewhere. Air has to be able to get into the tank to replace the water being drawn out. Or your tank will collapse.

So the "overflow" lines also act as vent lines.

Looping a vent line up from the top of the tank helps reduce "shrinkage" during travel. I can't think of a benefit to looping anything up from the bottom of the tank.

That being said, something could have changed. I'd be interested in learning about it if it did...

[Camper_bob]

Originally Posted by Doxie Campers

We are new (<4 mos) to Jayco, have a 2024 Jayhawk 30Z. Just got back from our 1st long trip where we experienced an inability to keep much water in the tank. We like to fill at least 1/3 so we are able to flush & wash when we need to on the road but found that by the time we got to our 1st stop, tank read "nearly empty". When we took it in to the dealership we learned this is due to the siphoning effect & the shape of the tank. Our dealer will fix by adding a loop of pipe. They've successfully solved this for "many" customers & say they've reported to Jayco over the years but no change by Jayco. So my question for this group: have any owners reported this issue to Jayco? Seems like if it's as common as it seems to be then they should just fix it before it's delivered to dealers! Thoughts?

Too many items to list in this category.

And you're not supposed to be towing with full tanks anyway, so why would they enhance your ability to do so?

[JKyle]

Originally Posted by TaftCoach

I solved it this summer by not try to fill every gallon every time and having my DW checking the gauge as we filled. At the first light flicker of full we stopped filling. We never ran out of water and never overflowed. It was a little more work but blowing out a tank by not shutting a valve is a vacation killer worse than the siphon.

This is what we did. Fill painfully slow, then when we are at least 1/2, unhook and refill if we need to. I made sure to buy enough length of hose to reach the local spout wherever we go. If I feel I can't hook up mid-trip due to distance, I will just fill up more, painfully and slowly.

[TaftCoach]

Originally Posted by JKyle

This is what we did. Fill painfully slow, then when we are at least 1/2, unhook and refill if we need to. I made sure to buy enough length of hose to reach the local spout wherever we go. If I feel I can't hook up mid-trip due to distance, I will just fill up more, painfully and slowly.

I didn't slow the flow. I kept the flow going full blast the entire time. We also were able to gauge the flow rate from 1/4 to 1/2 to 3/4 then to full with enough accuracy to avoid siphoning. It was the opposite of slow in that we didn't lose the time from any siphoning action.

[JKyle]

Originally Posted by TaftCoach

I didn't slow the flow. I kept the flow going full blast the entire time. We also were able to gauge the flow rate from 1/4 to 1/2 to 3/4 then to full with enough accuracy to avoid siphoning. It was the opposite of slow in that we didn't lose the time from any siphoning action.

First time I filled, all blast, learned my lesson quick. ALL the water came out of the tank. It confused me. I think I posted about it here. I realized my camper was on a slight tilt to the camp side of the camper, when parked in my yard. I thought that's what was causing it. Nope. I tried the power fill on my first trip, level ground and man, did I have a hard time figuring out, there was no way to avoid that siphon, unless I filled reeeeealy slow.

[Jolvi]

Originally Posted by Camper_bob

This can't work, because ... physics.

There has to be a vent in the top of the tank somewhere. Air has to be able to get into the tank to replace the water being drawn out. Or your tank will collapse.

So the "overflow" lines also act as vent lines.

Looping a vent line up from the top of the tank helps reduce "shrinkage" during travel. I can't think of a benefit to looping anything up from the bottom of the tank.

That being said, something could have changed. I'd be interested in learning about it if it did...

Sorry my bad I meant the vent was at the top of the tank with a vent hose connected to a vent on the fresh water holding tank.

[Johnynorthland]

Your fine if it vented out the overflow. I’m not familiar with your rigs water system but I would think if it went in any other areas chances are you have a leak.. Just don’t fill FW tank to the top anymore. I fill until full light starts to flicker, or if I’m empty I use a water fill gauge and fill to my max minus 5 gallons.