I have determined a small bit of order to this. Here is my method so far:
1) Open 3 separate windows or tabs, one for each Room.
2) I went from left to right, so I could keep track, changing 1 thing at a time only.
3) For instance, I started by first and ONLY changing valve 1 in Room 1. I then refreshed the other Rooms (by using the convenient link above the picture; NOT by refreshing any last action by using the Refresh button or key) and noticed if anything changed.
4) If anything HAD changed, I left the valve or lever in that position. If nothing had changed in any room, I switched it back to the way it was.
Through this, I have noticed that only certain valves and certain levers change certain things. (In my case, only 4 things create any changes: my 1st valve in Room 1 changes Room 3; my 2nd valve in Room 2 changes Room 3; my 2nd lever in Room 3 changes both Room 2 and Room 1; and my 2nd valve in Room 1 changes both Room 2 and Room 3.)
Having said all that, I still don't know what the aim or goal is here. I imagine there is a proper sequence of changing things (or even not changing things?) and I am still lost without any logic.
Next I might try flooding/resetting inbetween and trying only various combinations of *sequences* of actions that I know that create changes. And if that doesn't work, maybe try sequences of actions that I know do not create changes?
Curse TNT for making this puzzle so illogical! And I don't mean curse them in a friendly way.
EDIT: Siniri, I tend to agree with you. Some have even gotten it without changing anything in one of their rooms, so you can factor that in, too.