No one would answer me on THIS so I posed the question here. Someone else must have screwed it up and eventually got it right?
Before I posted the question, I presumed that 1) the "swirl tank" needs to be filled to capacity all the time. 2) the "overflow tank" needs to NORMALLY be somewhere about 1/2 full cold. That gives it expansion room and refill capacity both equally at 1/2 of it's volume.
I would think that both were calculated to be correct for the Panteras system based upon the entire system capacity AND the maximum expansion at maximum hot or whatever value the engineer presumed for that.
So my assumption here is that I need to substitute the same capacity "overflow" tank for the existing one?
@JFB. I am running the stock configuration. Pressure cap on the "swirl tank". Atmosphere cap on the "overflow". It's been running fine for quite some time now. I see no reason to re-engineer the entire system at all.
All things considered I'm still listening to everyone here. I am NOT the expert on this at all. In fact there is little that I am the expert on. I'm not highly intelligent, just highly experienced. "Are you experienced?" -Jimi Hendrix.
There has been much discussion about modifying the stock existing system with an attitude by some that presume the people who designed it were mentally defective and knew nothing. Interesting position?
PROBABLY what I will do, probably, leave both tanks where they are and just attach a hose line to the hose nipple on the overflow on the "overflow" tank and just run it to a catch can were it is accessible and be done with it? A definite maybe or maybe a probable probability?