While breaking down camp today I went to back flush the black tank and for the life of me couldn’t get the hose unscrewed so I hooked up a small hose from the sewer compartment water spigot to the black tank flush connection and let it run for awhile. I could hardly hear anything because the pressure from the spigot was so low so I closed the black tank valve so the tank could fill up and found out why the motor home user guide says “DO NOT CLOSE VALVE WHILE BACK FLUSHING”, the check valve does something to the studor valve in the bathroom sink cabinet (I think).
Water started flowing out the bottom of the RV, I’m standing there having a heart attack because I realize I’m filling something up in the RV and it’s flowing through the floor and then outside the bottom of the rig! I turn off the water and run like a mad man into the RV to see where the water is coming from and can’t find it! Finally I get to the bathroom sink cabinet and it’s soaked everywhere! I think the studor valve is inline with the back flush as a check valve, I could be wrong but if not I have no idea where the water came from! (side note, I should have turned it back on and had my wife see where it came from, but I didn’t).
I decided now would probably be the time to get the fresh water hose disconnected so I could hook up the water hose I use for flushing. It took awhile but now I know how my wife feels when I close things (jars) in the kitchen, she says everything is too tight for a normal human being. I don’t know how I got this thing so tight but it took a lot to get it loose! Finally I get it loose and get the flushing hose hooked up and everything is working fine.
I believe the water pressure from the spigot was so low when I closed the black tank valve it caused the check valve to kick and water flowed out the valve. I’ll have to locate the diagram I found to back this up. Anyway, I have always closed almost the whole way (about 95%) the black tank valve so the tank could fill up a bit and never had a problem, that I know of anyway,and probably because the pressure was great enough to keep water flowing.
Anyway, from now on, that valve stays open during back flushing! I am going to install a hose hook up inside so I can help the power flush because I really like to insure that tank is as clean as possible after each outing. I put about 10 gallons of fresh water into the black tank plus a concentrated tank cleaner for the drive back to storage. For the next outing I’ll back flush before we use the rig to get it really clean.
The good news is there has been no foul odors since they replaced the cyclone vent and the drive home was uneventful.