Fresh Tank Spillover Valve Upgrade

[Canyonlight]

Dan I did not make myself clear enough. The vent was in the screw cap, not beside. like the hole in the picture of post 11. So for those with exterior fill all they would need to do is change the screw on cap.to the vented style. Sorry if I was confusing, I guess you could make you own by drilling a 1/4" hole in the cap and placing some non rusting fin mesh screen inside with the washer over it to hold it in place.

Keith

OK..got it now, thanks, Keith. I never saw the vent in the screw cap....well at least that this old guy can remember !

Dan

[TedS]

[Canyonlight]

Thanks, Ted !

Dan

[AndrewSmith]

I'm also losing a crazy amount if water via the overflow hose in my Transcend.

I was planning to just put a ball valve on that hose (as the OP showed) but I read some more on this forum and realized that the tank needs to be vented both when filling and when using the water.

And apparently the tank also collapses and there's something called the syphon effect I don't understand.

Is it possible that the existing cap would be enough of a vent since it's not watertight, at least for when using the water pump? I know it is not watertight because one time I had water spill out of it when filling via the city water connection.

My problem with opening the overflow valve before using the water is that I'm on the road most days, I cook 1-2 meals on the road, 5 people use the washroom, and arrive at campsites dead tired sometimes. I'm just not going to remember to open it every time.

[Cate&Rob]

AndrewSmith

Grand Design has added the dual overflow/vent lines to most models. This breaks the siphon action that can happen through a single overflow line resulting in draining a considerable amount of the water from the tank by sucking in the walls and bottom of the tank as the siphoning continues. This fix will not stop "slosh" oveflow while driving, but this water loss is minimal compared to the siphon situation. Adding the second overflow line in parallel with the existing single overflow would require a T, a few inches of Pex line and a few clamps. More details at https://gdrvowners.com/forum/operati...problem-solved

Rob

[howson]

AndrewSmith -- Cate&Rob has come up with a solution that stops the siphoning (though not water loss due to sloshing but that's minimal). Honestly I'm not sure what it would take to incorporate his idea into an existing trailer. He'll see the tag and will respond so keep an eye on this thread.

If you'd like to read the info he's already posted, see https://gdrvowners.com/forum/operati...problem-solved

[howson]

Cate&Rob -- I moved your thread to the Reference Material section--we must have both been typing at the same time! (I was surprised we hadn't put your thread in the Plumbing's RM channel!)

[bellis]

Because the gravity fill on the 2400BH is vented - I have not been opening that valve when using the pump or city water. When I pump water into the gravity fill, I can feel the air push out through that vent (not fast enough - sometimes I remove the fill line and air gushes out.

As such - I don't think I am at risk of tank collapse. Great discussion!

[Country Campers]

Because the gravity fill on the 2400BH is vented - I have not been opening that valve when using the pump or city water. When I pump water into the gravity fill, I can feel the air push out through that vent (not fast enough - sometimes I remove the fill line and air gushes out.

As such - I don't think I am at risk of tank collapse. Great discussion!

Please make sure that the vent line is actually connected to the tank. I have not heard of one being connected.

I would guess that when you feel the rush of air come out when you remove the hose when filling tells me that the vent line is not connected. On our previous TT, another brand, the vent line was connected and there was never any rush of air come out when removing the filling hose.

Brian

[Cate&Rob]

Because the gravity fill on the 2400BH is vented - I have not been opening that valve when using the pump or city water. When I pump water into the gravity fill, I can feel the air push out through that vent (not fast enough - sometimes I remove the fill line and air gushes out.

As such - I don't think I am at risk of tank collapse. Great discussion!

See post 11 of this thread for what your vent “connection” likely looks like. Grand Design dies not connect this port to the tank.

Rob

[Guest]

bellis , Rob is spot on.

The gravity fill vent on my Imagine was not connected. I've also added the ball valve that many have done but one time I forgot to open the valve which could have collapsed and damaged the tank. To prevent this in the future I tee'd off the overflow and ran a line to the unused vent on the gravity fill. The line was easy to route along side the tank and under the sink area of our Imagine.



Jim

[AndrewSmith]

I don't have any photos but I've done something rather simpler.

I drilled two holes in the gravity fill cap, and covered them on the inside with that mesh-type drywall tape. I figured that will provide plenty of room for air to get out.

I'll still plan to open the overflow valve when filling, but now I don't need to worry about forgetting to do it.

Also replaced all the plastic drain vailves with metal ones. On a previous trailer I had the tank drain valve break during a trip, and it was just blind luck that I could fix it. It broke when I stopped at a farm for a couple of days.