Water Tank??

[Dick Simonis]

I'm getting a little tired of not being able to top off the FW tank, without running the risk of overflowing, and than siphoning the tank back down to the 1/2 tank level.

Consequently, I'm thinking seriously about adding a riser to the tank vent...sort of a vacuum breaker, but, and I know this is stupid, haven't yet found the tank much less how to access it.

Has anyone else addressed this problem??  I know I can fill it until the CMP shows 100%, but I'm unclear as to how much capacity is left unused at the 100% level.  Also, if it's near full....say at 100%, is there a possibility that driving will cause the water to slosh around, fill the vent tube, and start the siphon while on the road?

Dick

[Gerald Farris]

 Dick,
I think that the fresh water tank on your model coach is located between the frame rails in the top of your basement. The siphoning problem has been addressed by several Patriot owners, and it seems that the easiest solution is to drill a small hole in the top of the vent line at it's high point.

Gerald

[Edward Buker]

The marine industry is more into this issue as siphoning could sink a boat and I copied some info below. The issue would be getting an assembly mounted above the tank. You will have to figure out if that is possible.

A vented loop is fitted with a one way valve. This permits water to be pumped through the loop. However when the pumping is stopped and no more water is pushed past the vented loop, air is let into the pipes and the water level drops away from the loop on both side, thus preventing a siphon from occurring. The vented loop allows air in but not out.

http://www.myboatsgear.com/newsletter/vented%20loops.asp

Basically if you found the highest point in it and put in a T fitting with the extra leg facing up and added a smaller diameter flexible plastic pipe, than the vent line, down and out the floor of the strorage bay it would seem like that would work. Any siphoning should pull air through the extra vent line and should break the siphon action. You could jury rig something and try it with a sink and a bucket to be sure first. It is conceivable that you could start siphon action through both lines and need a floating anti siphon ball valve in the vent but I think the larger vent line that is siphoning would pull air up the smaller vent and break the siphon. May be some debate on this one...

This might work without the vent line exiting the coach if there was room to adapt and install this in the existing tank vent system at the high point.

http://www.westmarine.com/webapp/wcs/stores/servlet/Product_11151_10001_18881_-1?cid=chanintel_google&ci_src=14110944&ci_sku=18881

Later Ed

[Edward Buker]

Just saw Gerald's post. Have to love the simple solution...

Later Ed

[Dick Simonis]

Having had boats for more years than I can recall I'm very familar with the vent loops and I've also just used a tee with perhaps a stub on the top...perhaps not.  FYI, the drilling a small hole (I use a 1:4 ratio) also works very well if one can tolerate the possiblity of a very small amount of leakage...not a problem with water.

I still have to figure out how to access the top of the tank...once I find it.  That would be best but, alternatively, I could just find the vent hose and reroute it up...vent it...than back down.  Thinking the vent hose must drop down somewhere inboard of  the gen set or propane tank based on where I see the water running out.

[LarryNCarolynShirk]

On my '98 Patriot, I drilled a 1/8th inch hole in the 90 degree elbow at the top front of the water tank.  It still syphoned.  Because this tank is located against the ceiling of the bay, it is difficult to find a place to run a loop higher than the top of the tank.  I extended the overflow hose forward to the front cap area, looped it up and drained behind the front bumper.  That was my final solution.  I could fill the tank, and not overflow it, while going down the road.  In a caravan, you could always tell it was a Beaver caravan, by the water trails on the road at every stop sign, and turn in the road.

Hope this helps.

Larry

[Dick Simonis]

Larry, thanks for the great info.  Seeings as how I have not yet laid an eyeball on that tank I sort of expected that there may not be any room at the top and I was moving in the same direction.  Did you put a vent at the top of the tube extension before you ran it down the cap??  or just terminate it at a point higher than the tank top??

I'll be going to the Quartzside rally and didn't relish filling up the tank only to find half was missing before I even set up camp.

[LarryNCarolynShirk]

Dick, I do not recall placing a vent at the top of the loop.  That may help, but try it without.  If you still have a problem, just add a plastic fitting in the hose, and drill a small hole in the fitting.

Larry

[Keith Oliver]

In a marine application, the vented loop (siphon break) has a purpose, as the open end of the line the loop is used on may terminate in a thru-hull fitting that occasionally rests below the waterline. A siphon in such a location can sink the boat.  In an RV, you will never need to worry about your vent terminating below the external water, unless you are having a very bad day, so will never need a siphon break in the vent line.  Just terminate the vent line as high as possible.

[Jeremy Parrett]

Gerald,
 we have the same Marquis layout for the water tank. Where exactly is this 'vent' ??  Where is the forward end of the water tank if that is where the vent is located?
 I have again flooded my basement. Most if the water seems to be in the rear  inboard end of the basement . I thought it was the waterpump leaking.  Jeremy

[Gerald Farris]

Jeremy,
The vent line that is referred to in this thread is a issue only on Patriots. The Marquis that you drive has an automatic cutoff for the fill valve, so it prevents the tank from being filled to the level that can cause siphoning through the vent line.

If you have a water leak in the rear of your basement, it is either a water line or the water pump, since the vent line exits the front of the basement and terminates in the open area inboard of your Hurricane compartment. The highest probability is the water pump.  

Gerald

[Jeremy Parrett]

Gerald,
   many thanks......this was my first thought.....even though  a Shurflo water pump from Wahoo RV in San Jose del Cabo will cost me an arm and two legs !!      Feliz Navidad.   Jeremy and Jane.

[Gil_Johnson]

If you need a pump or repair parts, these folks usually have everything in stock and their prices are fair.  Regardless of what kind of pump you have, they have parts.

http://www.depcopump.com/

[Dick Simonis]

One of the things that really bothers me about this whole siphoning issue is why it should do it at all.  I can see overfilling the tank and starting the siphon, but once the water level in the tank drop below the vent....there may still be a vacuum in the tank but the water level should be too low to be expelled.

Unless of course the tank is plastic and the vacuum in the tank is collapsing it.  I had that happen on a boat fuel tank.  Don't laugh, I've also seen a 60' high steel water tank implode because an engineer made a mistake on the vent.  VACUUM SUCKS.

Regardless, I need to get to the bottom of this as I'm fairly certain something not good is going on.