Overflow

[rgvtexan]

3 lefts make a right!

[mel s]

Originally Posted by atodalen

A while back I heard of others installing a spring-loaded check valve in the overflow line.
That should be enough to stop the siphoning and would be a lot safer than installing a shut-off valve in the overflow line.
I put a shut-off valve on mine a few years ago and ended up removing it because I was worried that I'd forget to open it when filling or forget to re-open it when we arrived at our destination and started to draw water from the tank.
In fact I did forget to open it more than once after getting to our destination. I'm sure that all of that tank flexing from the vacuum wasn't healthy for the tank.
Al

atodalen
On my coach the fresh water "overflow line" is also the tank "vent line".

I added a shut off valve in the overflow/vent line. (to prevent siphoning and/or water loss while driving).
AND I added a "tee" and a "spring loaded check valve" in the overflow/vent line, (before the shut off valve).
BTW, IMO the advantage of adding a check valve in a overflow/vent line with a shutoff valve is that the check valve allows makeup air into the tank when the pump runs, (thereby preventing "vacuum flex" of the tank).

However, (because my coach has no "gravity fill"), when I fill the tank I MUST OPEN the shut off valve to allow the air to escape from the tank as it fills, (and to allow water to flow out when the tank is full).

NOTE:
The downside of having a shut off valve is that one must always OPEN it when filling the tank.... (if it is NOT OPENED the pressure of the incoming water can/will expand/flex the tank).

Mel
'96 Safari

[atodalen]

Originally Posted by mel stuplich

atodalen
On my coach the fresh water "overflow line" is also the tank "vent line".

I added a shut off valve in the overflow/vent line. (to prevent siphoning and/or water loss while driving).
AND I added a "tee" and a "spring loaded check valve" in the overflow/vent line, (before the shut off valve).
BTW, IMO the advantage of adding a check valve in a overflow/vent line with a shutoff valve is that the check valve allows makeup air into the tank when the pump runs, (thereby preventing "vacuum flex" of the tank).

However, (because my coach has no "gravity fill"), when I fill the tank I MUST OPEN the shut off valve to allow the air to escape from the tank as it fills, (and to allow water to flow out when the tank is full).

NOTE:
The downside of having a shut off valve is that one must always OPEN it when filling the tank.... (if it is NOT OPENED the pressure of the incoming water can/will expand/flex the tank).

Mel
'96 Safari

Looks like a great solution.
Al

[Finally Time]

No matter what method I used to fill the freshwater tank on my 2013 Vista 27N, and no matter haw full it was, it would siphon down to 1/3 tank. Even driving 1/4 mile from the fill station to my campsite in Yosemite Valley I lost about 20 gallons. The dealer cured the problem by routing the overflow hose as high as possible in the compartment, then dropping it down, basically a upside down trap. Works like a charm, the tank vents when filling and no more water loss when driving.