Thanks for the info, Ray I think mine maybe like yours. I have the fresh water drain and then in the UDC I actually have two valves. I dug out a piece of paper that says I'm supposed to open the closed one and close the open one. then turn on the water pump. Is this like yours.
Another question. I have not put water in my freshwater tank this year. However as I was getting ready to try and winterize my trailer by myself (first time) I noticed that now my freshwater tank showd 1/3 full. Where the heck did that come from. It was drained (I'm sure of this) last year when it was winterized, and I didn't fill it this year.