I agree with webclan, reduce to one brood box and place the Flow frame on top of it with a queen excluder.
We also are founding supporters living in a northern climate, and we too have had more problems with enticing the bees into using the Flow frames than those who enjoy year round beekeeping.
This year we are using one brood box and placing the Flow on top of it. After we harvest the Flow frames (fingers crossed) we will add our medium honey supers for the bees to put up their winter stores.
Good luck!
