Water Supply Siphon

Lawfive · 03-03-2010, 09:22 AM

I read the earlier posts a while ago about water siphoning out of the fresh tank during a fill. The solution was to close the air vent with an added valve of some kind when the siphoning started. Okay, then leave the valve closed while traveling. Doesn't that stop any water flow inside the coach? When reaching destination and opening up the valve, doesn't the siphon process start up immediately?

My 391 has a "corrugated" pipe as the water vent. It's sort of a 1 1/4" version of a sewer line. Searching around online I finally found a barbed fitting that should work on the end and allows a valve of some sort to be screwed into the end. Before I take off on this task, I would love to get some input from smarter folks who've already solved my problem. "Steal ideas from the best, with pride" is my motto.

NWJeeper · 03-03-2010, 11:46 AM

Quote:

Originally Posted by Lawfive

I read the earlier posts a while ago about water siphoning out of the fresh tank during a fill. The solution was to close the air vent with an added valve of some kind when the siphoning started. Okay, then leave the valve closed while traveling. Doesn't that stop any water flow inside the coach? When reaching destination and opening up the valve, doesn't the siphon process start up immediately?

My 391 has a "corrugated" pipe as the water vent. It's sort of a 1 1/4" version of a sewer line. Searching around online I finally found a barbed fitting that should work on the end and allows a valve of some sort to be screwed into the end. Before I take off on this task, I would love to get some input from smarter folks who've already solved my problem. "Steal ideas from the best, with pride" is my motto.

If you find where your tank is (mine is above the propane tank) you will notice access disks that can be removed to "access" the water pump area and the vent. I have removed one of these disks and just left it out. I then pulled my vent hose up out of the hole it was in and stuck it out the access port. That way the hose is more or less level with the top of the tank. I have also put a peal and stick zip tie anchor on the ceiling of the tank compartment and zip tied the vent hose up so that it runs higher than the tank for the most part. If you remove this entire panel then you have easy access to the pump and hoses in there. You could replace that corugated hose with a vinyl hose like the early '09 and earlier rigs had and that is easier to put a valve on too.

You are correct, simply adding the valve at the end of the vent doesn't completely stop the siphoning when you open the valve after a day of driving unless you blow into it or something to stop the siphoning action.

If the vent is closed, your pump will still pull water but it will collapse the tank. If this happens, fill the tank the next time with the valve closed and it will pop back out.

I will try and snap some pics of it and post them later.

LadyWindrider · 03-03-2010, 12:05 PM

I have read the post on the vent line siphoning problems, and while I don't have a coach, or that problem, I'm left wondering what is really going on. In order for the vent to siphon, the water level would have to be above and forced out of the vent. Then once the overflow is full, the water supply turned off, the siphon would start. As long as air was allowed in the tank, the siphon would continue until the water level fell below the vent, at which time air would be pulled in to the siphon hose, and the siphoning would stop. If no air was allowed in to the tank, the siphoning process would stop when a vacuum had been pulled on the tank itself. The location of the vent in regards to the tank, would determine the water level left in the tank after the siphoning has stopped. The vent has to be fairly high if not at the top, or you would force water out while trying to fill the tank.

Solution: If you can get to the vent hose inside the coach, find the vent line. Make sure it is higher than the tank. At the highest point of the vent line, install a "tee" and add an extra piece of hose running up the wall. This will act as a vacuum breaker, and prevent siphoning. Being a "vent" line, this will never see pressure and no water should ever climb up and out of this hose. The worst case would be foul smelling water, and maybe being able to smell that near this other vent line. This can be minimized by reducing the inside vent line to a very small opening. This will cure the siphoning problem, and no valves to buy or remember.

I may be wrong, just applying plain on physics here and how a siphon works. Someone correct me, and I'll take no offense.

ronhanson · 03-03-2010, 12:08 PM

The pump will pull sufficient vacuum to let you use water in the coach while traveling. You wont even notice a change in the flow rate. You may not want to do this for very long since you may damage the tank if it holds a vacuum, but I've actually forgotten to open my valve after arriving at the campsite and didn't remember until the next morning. Much water had been consumed with no ill effects.

When at the site, the tank isn't sloshing around enough to start the siphoning. Providing you didn't overfill the tank to a point it's pressurized and you hadn't consumed any water it's normally not a problem.

I would very much like to see inside the tank as to how the vent is configured. It's amazing how much water it can siphon out.

ronhanson · 03-03-2010, 12:13 PM

Quote:

Originally Posted by windrider

I have read the post on the vent line siphoning problems, and while I don't have a coach, or that problem, I'm left wondering what is really going on. In order for the vent to siphon, the water level would have to be above and forced out of the vent. Then once the overflow is full, the water supply turned off, the siphon would start. As long as air was allowed in the tank, the siphon would continue until the water level fell below the vent, at which time air would be pulled in to the siphon hose, and the siphoning would stop. If no air was allowed in to the tank, the siphoning process would stop when a vacuum had been pulled on the tank itself. The location of the vent in regards to the tank, would determine the water level left in the tank after the siphoning has stopped. The vent has to be fairly high if not at the top, or you would force water out while trying to fill the tank.

Solution: If you can get to the vent hose inside the coach, find the vent line. Make sure it is higher than the tank. At the highest point of the vent line, install a "tee" and add an extra piece of hose running up the wall. This will act as a vacuum breaker, and prevent siphoning. Being a "vent" line, this will never see pressure and no water should ever climb up and out of this hose. The worst case would be foul smelling water, and maybe being able to smell that near this other vent line. This can be minimized by reducing the inside vent line to a very small opening. This will cure the siphoning problem, and no valves to buy or remember.

I may be wrong, just applying plain on physics here and how a siphon works. Someone correct me, and I'll take no offense.

You are correct. I don't know how the vent is configured but I've seen it suck a tank 1/2 empty so the inlet reaches pretty far inside. It should only be at the top of the tank.

The problem with trying to raise the vent level or add any additional piping is the lack of room in the compartment. The tank goes right to the top of the basement.

LadyWindrider · 03-03-2010, 12:21 PM

If you can get a "tee" in the vent line, and a piece of hose high enough to prevent sloshing out the added hose, you'll break the vacuum and the siphoning will stop. The new hose can even point down and go out the same vent hole, you just need it to break the vacuum of the siphon. Then it really won't matter where the vacuum line is in the tank.

cfsoistman · 03-03-2010, 12:23 PM

Quote:

Originally Posted by ronhanson

The pump will pull sufficient vacuum to let you use water in the coach while traveling. You wont even notice a change in the flow rate. You may not want to do this for very long since you may damage the tank if it holds a vacuum, but I've actually forgotten to open my valve after arriving at the campsite and didn't remember until the next morning. Much water had been consumed with no ill effects.

When at the site, the tank isn't sloshing around enough to start the siphoning. Providing you didn't overfill the tank to a point it's pressurized and you hadn't consumed any water it's normally not a problem.

I would very much like to see inside the tank as to how the vent is configured. It's amazing how much water it can siphon out.

You nailed it! The problem occurs from the sloshing during travel not at any other time. I didn't have a problem for 2 years but last September the road, if you want to call it that, was a far from smooth,level or anything close and we rock n rolled our way in. It was there I check the tank that was 2/3 full when we left but now about 1/3 full. Water drops were present on the screen of the vent so I knew it had recently happened. Since I installed the valve - no water lost - open the valve once I set up and barely a tablespoon or two. Bought one 3/4 PVC Valve, it fits snug into the pool type hose they used. I cut a small piece off and inserted the valve and placed the small piece with the screen on the open end. Used a little bit of white electrical tape, which I already had and it looks fine. My problem solved!

ronhanson · 03-03-2010, 12:32 PM

Quote:

Originally Posted by windrider

If you can get a "tee" in the vent line, and a piece of hose high enough to prevent sloshing out the added hose, you'll break the vacuum and the siphoning will stop. The new hose can even point down and go out the same vent hole, you just need it to break the vacuum of the siphon. Then it really won't matter where the vacuum line is in the tank.

It's a great idea, but on mine you simply cant raise the level of the intake point for a vacuum breaker or the vent hose opening high enough to prevent water from coming out while traveling. You'd get a wet basement. There is a slide above the tank so you cant even go into the house with any plumbing. The valve is a simple solution providing you can remember to open it. Once it's part of your setup 'routine' it's not that big of a deal.

flyrotor · 03-03-2010, 01:08 PM

Just wondering, considering windrider's suggestion, and listening to the comments about space limitations.

Using the tee as mentioned, would you be able to install a short nipple capped with an anti-siphon valve as used in the sprinkler system industry? The intent of the anti-siphon valve is to prevent water leaking under pressure, and allow it to drain when not under pressure. This potentially could "break" the closed system which causes a siphon, but prevent water from leaking out when sloshing. This might be a good subsitute for the hand valve which could sometimes be forgotten. Goes along with windriders setup, but may well fit into the space limited compartment and prevent soaking everywhere.

Just a theory, would it work? My trailer doesn't siphon, but I have seen it squirt out when making right turns.

NWJeeper · 03-03-2010, 01:40 PM

Quote:

Originally Posted by windrider

In order for the vent to siphon, the water level would have to be above and forced out of the vent. Then once the overflow is full, the water supply turned off, the siphon would start.

One of the big problems with our coaches that is different than a lot of others is that our tanks are the full width of the rig but only about 4 or 5" high. It only takes just a tiny bit off level to the passenger side to get the siphon going. Most other coaches have tanks that are 12 to 18" high and when vented properly there is no way for them to siphon.

Charlie hit it right on the head that while traveling that short tank combined with the rocking of the rig means you can loose 2/3s of your water over a day of traveling. From the top of the tank to the top of the compartment it is in is only mere inches so I don't know if there is enough room for a "T" in there but I like the idea.

ronhanson · 03-03-2010, 02:13 PM

Quote:

Originally Posted by flyrotor

Just wondering, considering windrider's suggestion, and listening to the comments about space limitations.

Using the tee as mentioned, would you be able to install a short nipple capped with an anti-siphon valve as used in the sprinkler system industry? The intent of the anti-siphon valve is to prevent water leaking under pressure, and allow it to drain when not under pressure. This potentially could "break" the closed system which causes a siphon, but prevent water from leaking out when sloshing. This might be a good subsitute for the hand valve which could sometimes be forgotten. Goes along with windriders setup, but may well fit into the space limited compartment and prevent soaking everywhere.

Just a theory, would it work? My trailer doesn't siphon, but I have seen it squirt out when making right turns.

I don't know how touchy the Anti-siphon valves are, but a pure check valve would not work since you need to displace the air when filling the empty tank. Would that be enough to close the anti-siphon? I have no idea.

Lawfive · 03-03-2010, 03:51 PM

Next week I'm going to stop by a professional sprinkler supply house. As an aside I'm going to pick up a 6" diameter pvc pipe about 6-8 feet long with end caps so I can store my sewer hose in it. I'm tired of rolling it into a big plastic storage container.

While I'm in the supply house I will talk to the guys there about anti-siphon techniques. I'll be they've got something that might do the trick.

cfsoistman · 03-03-2010, 04:02 PM

Quote:

Originally Posted by Lawfive

Next week I'm going to stop by a professional sprinkler supply house. As an aside I'm going to pick up a 6" diameter pvc pipe about 6-8 feet long with end caps so I can store my sewer hose in it. I'm tired of rolling it into a big plastic storage container.

While I'm in the supply house I will talk to the guys there about anti-siphon techniques. I'll be they've got something that might do the trick.

We have the bath and a half so with two draining points I went with the sectional drain piping from Camping World and made holders. I store 45 feet of hose and fittings in one area at the rear drain point compartment.

http://www.forestriverforums.com/for...php?albumid=27

Just an idea in case it might work for you.

LadyWindrider · 03-04-2010, 12:03 AM

Hey guys, hope I didn't upset the apple cart here. The ball valve is a sure thing. Just offering a suggestion that would be automatic, and not require electricity and and/or manual labor. If you check with the plumbing guys, ask about a "vacuum breaker". That is essentially a check valve with a very weak spring. They put them on hoses for washing machines, outside frost proof spigots, and other things. Stops water from going out, but allows air in, thus breaking the vacuum. That's why they call it a vacuum breaker

NWJeeper · 03-04-2010, 12:07 AM

Quote:

Originally Posted by windrider

Hey guys, hope I didn't upset the apple cart here. The ball valve is a sure thing. Just offering a suggestion that would be automatic, and not require electricity and and/or manual labor. If you check with the plumbing guys, ask about a "vacuum breaker". That is essentially a check valve with a very weak spring. They put them on hoses for washing machines, outside frost proof spigots, and other things. Stops water from going out, but allows air in, thus breaking the vacuum. That's why they call it a vacuum breaker

Hey I love "automatic". Keep the suggestions coming Windrider. One idea I had early on was to put an electric solenoid valve on the hose, dual action so no voltage is required to hold it in either direction (open or closed) with a switch on the wall. Could be set also to automatically close when sensing the ignition on (on a motorhome).

cfsoistman · 03-04-2010, 07:31 AM

Quote:

Originally Posted by windrider

Hey guys, hope I didn't upset the apple cart here. The ball valve is a sure thing. Just offering a suggestion that would be automatic, and not require electricity and and/or manual labor. If you check with the plumbing guys, ask about a "vacuum breaker". That is essentially a check valve with a very weak spring. They put them on hoses for washing machines, outside frost proof spigots, and other things. Stops water from going out, but allows air in, thus breaking the vacuum. That's why they call it a vacuum breaker

I've been in construction for more than 35 years in the HVAC field as well as working right along with our plumbing group. I understand the function of the Vacuum Breaker but you still need to displace the air when filling the tank. It won't allow water or air to escape, it will allow air in when you are using water from the tank only. So the vacuum breaker would not be the answer to this situation.

Lawfive · 03-04-2010, 09:19 AM

Windrider thanks for the idea. Charlie explained what I thought would be the filling problem. Now maybe a "Y" on the end with a check valve for a siphon stop and something else for an air bleeder during filling. Now I'm beginning to understand why the FR design guys threw their hands in the air and said deal with it owners. Or, maybe worse never foresaw the problem.

Again, I gonna make a stop at a professional sprinkler shop though maybe a pool builder might be more appropriate. My pool filter works sort of the same way and has a manual air bleeder at the top. At least I will check with them for a magic bullet.

Charlie, thanks for the pics of your hose storage solution, cool. Forty-five feet. Wow, and I thought I had a big hose.

My idea with the closed PVC is to keep those last offensive amounts of water contained. No matter how I rinse the hose, it is never perfectly clean. I've been coiling it into a plastic bin but that's a pain. Hence a capped pipe. Drop in the slinky sewer pipe and cap it off. Saw a product for sale somewhere to do this and decided I could make it myself in the perfect size too. I love stealing ideas and doing my own thing. Comes from a career in computers I guess. Look what Bill Gates did with Windows.

I'm headed to Vancouver Island next week (by air darn it) but will try to post any thing I find before I leave.

cfsoistman · 03-04-2010, 11:06 AM

What I like with this system is the pipe lengths are 10ft and 5ft. I have three of each. Depending on the location of the sewer drain at the camper site I can configure the drains to come to a "Y". Also rinsing out 5 or 10 feet pipes are easier than 25 feet. I rinse them and put them on the holders I made then lean them against a tree so the water drains out while I'm wrapping up everything else before we leave. Then I put them away. Is it 100% odor-free?, almost, I usually wash out the storage area once we get home.

flyrotor · 03-04-2010, 08:47 PM

Quote:

Originally Posted by cfsoistman

I've been in construction for more than 35 years in the HVAC field as well as working right along with our plumbing group. I understand the function of the Vacuum Breaker but you still need to displace the air when filling the tank. It won't allow water or air to escape, it will allow air in when you are using water from the tank only. So the vacuum breaker would not be the answer to this situation.

The thought process is that you would install the vacuum breaker on a tee, which would allow the normal flow of air escape via the vent hole. The vacuum breaker would then be placed as high as possible in the restricted compartment.

LadyWindrider · 03-04-2010, 09:23 PM

The electric solenoid is a great idea. Check the voltage on the valves for a rainbird sprinkler system. I installed several in a green house operation some years ago. Can't remember if they were 12 volt or 18 volt. If twelve volt, would have to operate a toggle to fill tank, then turn toggle off, removing voltage so valve would close, and transport. Could also run a wire from the pump pressure switch to open the valve when the pump ran, this letting air in. Sounds like a plan.

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