John, took the whole assembly out of the UDC. Unscrewed the fittings and there is nothing but air in there. Haven't a clue as to where the so called check valve is. Is it possible that the pressure regulator is not allowing enough water to get through the system? Read the owner-written guide and will be heading to the RV parts place tomorrow to get me one of those back flush gizmos. Thanks to all for the replies.
THANKS!! You've just vindicated something I said a couple of years ago when my UDC flusher fitting broke. The black plastic B&B Molders fitting is nothing more than a hollow tube flow restrictor, not a check valve as some have said. When mine broke, I replaced it with a brass city water fitting that has an actual check valve in it.
In regards to the pressure regulator you mention, if it's one of the little blue plastic gizmos they sell at the RV parts store, WallyWorld, or they stuck in your owners package at the dealer, it's probably not passing very much water volume. Those are also more of a restrictor than a regulator. You best bet for a regulator is to use either the Watts N55BG or 263A regulator from these folks:
http://www.rvwaterfilterstore.com/ They're a great source for water filter info and parts, along with quality hoses for drinking water. Pricey to some, but you get what you pay for.
Other question: When you were trying to run the flusher, could you hear anything behind the basement wall? I run mine off my filtration system, but I can still hear it. With your hand on the hose, you should be able to feel if the water is running through it, too. If you don't hear of feel anything, you could try loosening the basement panel next to the UDC to hear and see. Most likely, your anti-siphon valve is mounted in the wall directly behind the toilet, not behind the shower. I have the same rig, and that's where the piping goes. Have you tried running the water into the flusher without any regulator/restrictor? If you for certain don't have any flow, then it's possible the anti-siphon valve is blocked (or backwards).
If you look in the center of the photo (one of my Basement-O-Doom collection), you'll see two red PEX lines disappearing into the overhead at the rear. That's the lines to and from the anti-siphon valve in my 2009 BH3670. The one attached to the white vinyl hose goes to the flusher in the side of the tank. I've installed access panels on both sides of the basement so I can check back there for leaks and get to my converter and suppressor (which you don't want positioned under anything with water in it).
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