I bought my first classic Flow Hive in October/20 and I bought a colony for it but it had a few issues (the queen stopped laying at the time that, for health reasons I could not attend the hive). In addition I’m coming back to bee keeping after 35 years, so I consider myself a novice.
It took until mid January to get the colony strong enough to add a Flow super. Then it took a long time for the bees to start colonising the super. Now the colony is strong, the brood box is full of bees, capped brood, and even the outer frames are complete with caped honey. The flow box however, might be only a third full of honey but there is a reasonable amount of bees in it.
Given all this, I have a few concerns:
If I take the Flow box off for the winter,
1- Am I going to be packing too many bees in one brood box?
2- Are those bees going to have enough honey for the winter?
3- Should I take the Flow box anyway and then feed them? dry sugar or syrup? white sugar or raw sugar?
4- Should I NOT take the flow box so they have the honey available for the winter.
5- Assuming that is not a good idea to take the queen excluder are those bees going to be warm enough?
Advice will be appreciated
Marcus
Hi Markus, welcome - and welcome back to beekeeping 
Great questions! I’ll leave the best climate-related answers to those in your area, but can give you some general thoughts to go on for now:
1 - if your winters are cold enough to create a nectar dearth and brood production will thus decrease, your bees will condense as the population shrinks until late winter/early spring.
2,3,4 - assuming cold winters, drain the Flow box, remove it and the QX and use a top mounted feeder setup - you can either feed this honey back to the bees, use dry white sugar or a 2/1 white sugar syrup. Check for more directions on those options. If the honey you take off the frames is high in water content due to mixing with uncapped nectar, it can be refrigerated or frozen til you need it.