Fresh Water Tank on '05 Sun Voyager

[Sudsy]

Hello all;


I am trying to figure out why it is that when I fill my fresh water tank it seems to siphon it entire contents through the overfill tube. When I hook up "local" water and put the selector valve in the "tank fill" position it fills just fine. No drips from anywhere. I can actually see the top of the tank in one of the basement compartments so I can verify it is full. Today when I verified it was full I turned off the supply and I still had a steady stream from the overflow I tested the levels and the fresh water showed full. The water continued to flow from the overflow. I switched the valve to "local supply" and the water started to flow out of the fill. I plugged this with the plug for the fresh water feed/fill hose. The water continued to flow from what appears to be the overflow until the tank is empty. I had to leave at this point and when I returned the tank showed empty. The coach is parked with the right side very slightly low. Could it be a clogged vent tube?


Sudsy

[Chuck v]

Sudsy,


If you fill he tank only partially (say half to a bit more...) does the overflow still have water coming out? I would think that a partial tank could not start a siphoning action. Otherwise look for a source of air or water pressure that is forcing the water out the overflow and starting a siphon. On my rig there is no 'fill' position on the pressure shore water connection -- only the gravity feed to fill via a separate port. I would think that the overflow tube comes from near the top of the filler neck and would not sustain a siphon as the water level drops below overfull in the fresh water tank...


Chuck

[Sudsy]

Sudsy,


If you fill he tank only partially (say half to a bit more...) does the overflow still have water coming out? I would think that a partial tank could not start a siphoning action. Otherwise look for a source of air or water pressure that is forcing the water out the overflow and starting a siphon. On my rig there is no 'fill' position on the pressure shore water connection -- only the gravity feed to fill via a separate port. I would think that the overflow tube comes from near the top of the filler neck and would not sustain a siphon as the water level drops below overfull in the fresh water tank...


Chuck


Ye Chuck, I'll give that a try. I can see, as I said the top of the tank. So I can stop it before it starts to flow thru the overflow. When it first happened I thought the tank had swollen from pressure (and maybe that's what got it started) and the flow would stop if it went down.


Ok running outside to do some test now. Got a neighbor coming over to have a look too.



Sudsy

[Sudsy]

Well now I have filled the tank to what appears to be about 2 inche from the top. The tank level is showing a full tank. It is holding water and nothing is coming out of the overflow. We did find a white plastic assy that I thought was a capped off thru tank fitting. My buddy said if you put your finger in the end of the thing there is a spring loaded valve there. Now if this thing is indeed siphoning itself almost empty the overflow outlet must have a vertical tube similar to the fuel pickup for the generator. If this is the case then pushing the valve we just found should break the siphon. Also if I disconnect the fill hose and place the selector valve in the "fill tank" position should also break the siphon as soon as it clears itself of water. It would be interesting to see exactly how much water 50 gals is in the tank. That is what is the advertised capacity.



Sudsy