Thank you Kristijan.
The drain is an ordinary 1 1/4" valve with the handle above bed. Right above on top of the tank is the vacuum line attached. That's where i put down that small rod to punch out the bottom sediment. I expected it to start draining by itself. It usually does when things are still hot (and no cameras are rolling).
Low temps, more water in the tank - yes. High temps, less water in the tank, more water in the hayfilter.
Bedtime now. My alarm screames 4.20 am.