Water tank overflows-I may know why

[two2go]

Well folks, it was definitely the 3-way valve that selects between tank fill and city water supply. I pulled the panel yet again, pressured up the system, and then disconnected the pump inlet hose and the tank fill supply hose in turn. Nothing from the pump. Steady little stream from the valve to the tank line. Just for grins, I put the new pump in. It made no difference and still "burped" every couple of minutes. But it is a nice quiet new pump, so no loss there and I have a good spare.
Could not locate a local source for a Watts valve. I am getting an Apollo valve from a Florida supplier. The valve looks pretty similar-may have to mod the mounting screw holes but it will do the trick I am sure. In case anyone cares, the Watts was a series B6780 and the Apollo is a series 70-600.

[two2go]

Final update-go to my post on "Dolphin water system saga-done!"
Original Watts valve ball was corroded which chewed up the seals a bit, enough to leak.
Supplier sent a Watts valve after all, wrong size. My solution in above post was to put in a cheap PVC valve. All is wonderful. No more back leakage to water tank and no intermittent pump "burping."

[derouen6]

The problem with the valve is that it is installed backwards. This valve allows 1/2 flow when hooked up in one direction and full flow in the other. If you remove the valve, turn it around, the problem will go away. You will have to buy a short hose for the local hardware store to replace the custom one curently installed on the RV. If you want to secure the valve with the provided serews, you will have to drill holes on the opposite side of the valve stem opening. Hope this helps.<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by two2go:
Richard S, thank you for the info. The Watts valve is the one, and I found a local supplier. Yes, I tried tightening the handle nut, but there is an internal leak around the ball itself apparently. I may take a belt and suspenders approach and also install a backflow preventer valve to the pump inlet just to be sure the water stays where it should. Now that I solved the winterizing inlet suction problem (my other thread-"Winterizing, this didn't suck"), maybe I will finally have a properly functioning system. </div></BLOCKQUOTE>