Filling the water tank

[Glenn Scherrer]

I have a 1998 patriot  when I fill the water tank until it's full and the water starts leaking out the over flow pipe the water runs out until the tank reads 3/4  if I stop the fill just before it reaches full I don't loose any water   Why is this happening ?

[Dan Murphy]

It is a siphoning effect. I cannot fill my tank completely full either.

[Roy C Tyler]

It sounds like you may have an overflow pipe that is 'U" shaped and it continues to siphon the water out of the full tank until the level of the tank is to the bottom of the overfill pipe and the suction is finally broken.  This is just a guess on my part.

[David T. Richelderfer]

This has been discussed in the forum.  Do a search using "siphon" and you will find it.  There you will find an apparent "fix" and a trick, both of which will stop the siphoning with minimal loss of water from your fresh water tank.

[Michael Marcocchio]

Hello I have the perfect solution to that problem I cut a hole in the top side of my water tank add a threaded plug now I can fill my tank faster and without problems with a hose and add tank cleaner though the threaded hole. Any one interested I took pictures but I would need your email as I don't know how to add pictures on here.

[Gerald Farris]

Glenn,
Many of late SMC era Patriots (1997 to 2002) had this problem. It is caused by the way that the overflow pipe is plumbed into the tank. To correct the problem you need to install a vacuum break into the high point on the overflow pipe.

Michael,
You can not cut a hole into the SMC era water tanks and fill them manually because the tanks are mounted in a non-accessible location, like between the frame rails above the basement.

Gerald

[Dick Simonis]

I fixed mine by creating a vacuum break/air gap.  Since mine is located between the frame rails it considered dropping the the tank as too difficult so I fabricated a 1 1/4" piece of pve pipe that would slide over the existing PEX overflow line.  Then I reached up as high as possible and drilled a couple of 3/8" holes in the PEX.  Once the hole were drilled, I shoved the PVC pipe up as far as it would go I drilled a small hole in a hose clamp and attached it to the same hole that was used to hold the PEX.

Once you crawl underneath and see the overflow it all makes perfect sense.

The PVC pipe was only installed to keep the overflow water from spilling on the coach chassis.

Works like a champ and now when it overflows it runs for a bit and stops.

[Glenn Scherrer]

Would a hose Bib Vacuum Breaker or Anti-Siphon Valve  placed on the end of the over flow pipe work?

[Dick Simonis]

Would a hose Bib Vacuum Breaker or Anti-Siphon Valve  placed on the end of the over flow pipe work?

No, you have to break the siphon as close to the tank top as possible.

[Keith Oliver]

I have had some success filling right up if I leave the tap running at the water bay while filling.