Winterization puzzle ?

[RIDER FAN]

I am in the process of winterization. My MH is an HR Endeavor with a 10 gal hot water tank on passenger side. I have drained system and pulled out the 7/8" drain plug on water heater and gone into bay , opened little door and put the bypass lever in the UP position. I have a hose hooked into the wintering port on drivers side of water service bay and the other end in a 5 gallon pail of RV non toxic anti-freeze. last year i just hit the pump on and it sucked up the AF and i cracked all the taps ,hot and cold , low water drains and the pink fluid came out and all was good. Also drained ice maker and put a cup or so in the P traps.
This year the pump will not suck up the anti freeze. I actually blew on the hose to push AF in. On further investigation it was going into the hot water tank and dribbling out the 7/8" drain hole. Unless i'm loosing it.......i'm positive i have had the bypass lever in the horizontal position all summer and i have had hot water in the shower always. For some reason if i have the lever in the horizontal OR vertical position the AF is going thru that hot water tank...........could the valve be bad ? I only move it once a year so i wouldn't think its worn out ? The year is 2005 HR Endeavor. I'm sure the lever must be in the up or vertical position to bypass..?? Does the "Tank fill -City water" lever position have any bearing whatsoever.......?? Thanks for any input ,Going back out today to see if i can complete the job.

[BFlinn181]

If you only have the one valve for bypassing the WH, then it's depending on a one way valve at the WH outlet to prevent back flow. That valve may be blocked with lime deposits and failing to close. You could try pouring a couple of gallons of vinegar in the tank and soaking the valve.

[bborc]

I had the same problem last year. On mine there was a small plastic check valve plunger that is supposed to stop the back flow. It had broke. I just took the tank out and plumbed in two valves to by pass water heater.