What is the difference between he dry sugar you are using, and sugar water? Water. More of it. In my newbee brain, I would just put the sugar in and spray it a bit to give them water to help proces it. Or maybe a candyboard? If it is too cold to feed syrup without it freezing, i wouldnt want to put it out, even if you can heat it. You dont need ice in the comb or hive top. Just my humble thoughts.