I will bring this thread back gently to poly if I may. What I find incredible still is so many do not or will not use top insulation when it is so obvious. Virtually no one who teaches seems to know that the OMF was invented to improve Wintering before varroa ever arrived here. The open mesh floor in the research was coupled with top ventilation for best results. So even if you for what ever reason/s are again using poly for goodness sake put that bit of insulation over the CB and uses for that matter solid crownboards to help the bees keep cosy. I cannot understand why this is such a difficult concept. Bees like to be warm. It's that simple. I won't put up the link but a simple google on Mobus and Wintering will give the info.
PH
