Re: Economical honey heater.
I use the same thing only I use a small forced air thermostatically controlled heater and set the hive bodies on a bottom board to give the air a way to circulate. Set down the bottom board, set heater on bottom board, bottom hive body, queen excluder ( I use a wire shelf), then another hive body or two, then the lid. With the heater facing the back of the box, you can run cord through what would be the entrance of the hive. The entrance gives enough air flow so the heater does not overheat.
"Of all God's creatures, only the honeybee improves its environment and preys on no other species."--Haydon Brown