Water venting issue in Open Range 2021 212FB

[SeventyGTX]

I just picked this up a couple of weeks ago and it was still winterized by the previous owner. I drained all the anti-freeze out of the lines and flushed it with fresh water. But still have two problems. First I cannot fill the hot water tank even though all the valves seem open.

Second, I tried using the black tank flush and could not hear water running into the tank and after a couple of minutes it was running on the ground from underneath the trailer! We had a Jayco 5th wheel and you could always here the sprayers working when the water was on, not this one. I went inside and traced it to a pair of lines under the bathroom sink that were tied together with a vent cap on top. At first I thought it was the sink lines because this vent was zip-tied behind the sink way up high. I cut the zip tie so I could see what the heck it was. Anyway, the crazy thing is I had the black tank drain valve open, so not sure why it would not vent, and what would force the water up those lines and not spray the tank?

Here is the vent that water was puking out of.

 

[OldWEB]

Post a picture of the water heater bypass valves.
The above picture is of your tank flush anti-siphon valve, read about it here.

 

[SeventyGTX]

Ok and thanks for the quick reply!

Here are the lines going to the hot water tank and below that the valves under the kitchen sink. The only one there I'm not sure about is the one with the blue lever. It is facing 90 degrees to the lines, but the line going down from it is open, like some kind of a drain, see third pic.

 

[JBright11]

The open line is the pickup line to pump anti-freeze into the lines. If you turn on your water pump and there is suction on the open end that valve is open.

 

[SeventyGTX]

The open line is the pickup line to pump anti-freeze into the lines. If you turn on your water pump and there is suction on the open end that valve is open.

Ahh, ok thanks. I never used anti-freeze in our previous RV's and just blew the lines out in winter and will do the same with this one.