Fresh water tank questions

[bilco82]

I have a 2014 Eagle 5th wheel, with a 48 gallon fwt. The tank fell off on our way to a week long camping trip in Southern Indiana last month. It appeared that some of the self tapping bolts were stripped when the camper was built. I got a new tank, and I'm wondering why I need the overflow lines if I hook up the vent. The tank has a vent opening that releases by the fill hole. The same venting system I've had on my 3 previous campers, that I never had a problem with. If I connect the overflow lines I lose about 20% of my tanks capacity, as my tank is 5" tall and the bottom of the overflow is 1 3/4" from the top. Do I really need these overflow lines, and why 2 instead of 1? Jayco has not been very helpful with this process, and I'm hoping somebody on here can give me some good advice. Thanks in advance!

[oldmanAZ]

Welcome to the forum.

Vent lines are a frequent topic on this site. The usual complaint is water loss due to siphoning while on the road.

IMO, the additional vent line is to allow water to escape when the tank is full to be sure the tank does not become pressurized when filling. The vent in the filler line has enough capacity, IMO, when pumping water out of the tank, but may not be sufficient when filling.

In your case, consider routing the overflow line(s) in a loop above the tank. You'd have the overflow capacity, but routing the line above the tank would prevent water loss due to siphoning when towing and you'd gain the added capacity above the vent line attachment to the tank. A win win!

Good, bad, or indifferent... that's my advice and it's worth every cent you paid for it!

[wabirch]

Good thoughts here

[Jagiven]

Scary thought to be traveling down the highway behind a camper and see the tank fall out! Hopefully no one got hurt.

On my 2012, the vent line to the gravity fill port is not used. It actually has been caulked shut on the inside of the TT. I bet yours is the same, you could open it up and use it. Personally, I would use Jayco's design for the overflow, and insert a small 1/4" tee, and bring that up to the gravity fill port vent, so that you could eliminate the siphoning effect. IMHO the Tee would need to be located between the tank and the high point of the overflow tube.