Deep or medium frames? 8 frame or 10 frame hive bodies? I would put foam board fillers either side of the brood and honey frames to minimize the amount of space to heat. Foam board will have to be wrapped in heavy poly and taped to prevent chewing. For certain you should put top feed of sugar on top of frames. That would require a feed rim or lift about 1 1/2" high. Needless to say, insulate and wrap and be sure to have at least a small upper vent and exit a few bee widths opening.
What are the natural ways of dealing with EFB? Is is still aborting a high percentage of open brood?
What are the natural ways of dealing with EFB? Is is still aborting a high percentage of open brood?