fresh water tank possible vent blockage

[lone_ranger]

I have a 2004 Alumascape 30 SKS. When I fill the fresh water tank until the excess water flows out the overflow pipe I turn off the water to the inlet connection and the excess water exits but it continues to drain for about an hour and there is only about 1/4 to 1/3 water left in the fresh tank. I suspect the vent to the tank is blocked. I don't know where it is and don't want to take the underbelly cover down if there is a better fix. Thank you for any help or suggestions. Where can I find the vent to check it?

[MFL]

CC-skipjack wrote:
In my C.C., the fresh water vent is a clear plastic hose which plugs into a small plastic screen very near the water hose connection. My fresh water tank also has some sort of floating, leftoevr from buidling material, in it that causes it to block while filling. While filling the tank, I monitor the air flow from the vent. When it plugs, I need to unhook the vent hose, stick my head in the basement door and blow back into the tank to clear the blockage. This may need to be done several times while filling. Truly a P.I.T.A. but I want to make sure my tank is full before heading to my campsite.

Good luck finding your vent. I know before realizing this was an issue I would fill until the water flowed from the fill opening but always ended up with less than a full tank.

You just need a short 6" piece of hose, to hold against your vent screen, to blow into, to clear the vent.

Jerry

[CC-skipjack]

In my C.C., the fresh water vent is a clear plastic hose which plugs into a small plastic screen very near the water hose connection. My fresh water tank also has some sort of floating, leftoevr from buidling material, in it that causes it to block while filling. While filling the tank, I monitor the air flow from the vent. When it plugs, I need to unhook the vent hose, stick my head in the basement door and blow back into the tank to clear the blockage. This may need to be done several times while filling. Truly a P.I.T.A. but I want to make sure my tank is full before heading to my campsite.

Good luck finding your vent. I know before realizing this was an issue I would fill until the water flowed from the fill opening but always ended up with less than a full tank.

[Ron3rd]

lone ranger wrote:
I also fill and drain the black tank three times before I leave a campsite. A plumber friend told me to try it and I was amazed how much is left in there. I leave it soak for awhile to loosen everything real good. Try it and see.

That's a very good idea, and use a clear elbow to see the junk coming out and when the tank is clean.

[lone_ranger]

I also fill and drain the black tank three times before I leave a campsite. A plumber friend told me to try it and I was amazed how much is left in there. I leave it soak for awhile to loosen everything real good. Try it and see.

[lone_ranger]

OK. Update on FW overflow. The exit for the overflow is on the lowest point outside of the under cover. There is a rubber fitting pushed onto a 1/2" threaded brass nipple. I took the rubber fitting off the nipple and started filling the FW tank but not at full pressure. I filled slowly so the the tank would not expand more than normal when it is full. As soon as the first dribble came out of the nipple I turned off the fill hose. The overflow was a small amount for a few seconds. The panel indicates that the fresh water tank is full. I can only think that the position of the overflow tube inside the tank is way below the top of the tank, approx at the 1/3 level and once the tank is expanded way more than normal because I have the hose bib in full open that when it starts out the overflow nipple it starts syphoning and won't stop until it seeks the inside end of the pipe. I'll check things later to ensure it is not syphoning anymore. Yes all the tank level indicators work and are accurate. When I fill the black tank between trips and winter storage I use a flashlight and can see when the toilet becomes full to the throat. I've been keeping all tanks full when not in use and I think it has kept the sensors in the tanks from corroding. I just checked and there is no syphoning and the panel still indicates full.

[joebedford]

You know you can't trust the level lights, right?

I don't understand why your overflow would siphon the tank - the overflow is supposed to be at the top.

[lone_ranger]

I bought it new in 2004. When we dry camped until 2009 I never had a problem. And no problems until our last trip a month ago and thought I just forgot to fill after we got home but it drained out last week and I thought it stopped because the pressure was gone but today I noticed the level indicator on the panel showed 1/4 full. So I refilled it and it drained out the overflow for an hour before it stopped at 1/4 full. But this year it started syphoning out. I fill it and store it until the next trip a month apart. It used to expand from pressure and excess water would flow out overflow outlet for about 5-10 minutes. the overflow opening has a rubber flapper type valve for one direction flow out and seals itself so it can't suck anything in. I store it here at home and go in it often and I hear the overflow valve fluttering.

[GordonThree]

The overflow is the vent, at least on the various trailers I've laid eyes on, including my current trailer.

Is the trailer new to you, did this problem start recently?