I attempt to run all hives with two queens for cut comb
honey. Base hive is 3 full depth supers,old queen bottom,excluder with
cleats on 3 sides to make available an entrance at the front for the bees of
second box which has the second queen. Second excluder on second box,third
box for honey and to act as a buffer to keep pollen out of comb honey. Works
OK.Last season I tried 3 queens and it worked no trouble so I guess the
number of queens that you run using the vertical system is limited by the
height of the ladder that you own.
                Have just received manual from Un.Minnesota Extension
Service "Beekeeping in Northern Climates" which says on page 43"research
shows the horizontal two queen system is more productive than the vertical
two queen system" so I guess its back to the drawing board for me.
                                                RBB.