Home DIY TipsDIY “5 Gallon Bucket” Sand Battery Air Heater! Homemade Sand Battery Air Heater with Copper! Easy DIY! ~ How it works: room temperature air is blown over a very hot “copper topped” sand battery located inside the bucket. the copper strips act somewhat similar to the fins of a radiator – soaking up and spreading out the heat. the fan then blows down on it and the air is heated. air temps in the bucket top out around 140F(60C) so it holds up fine. bucket is rated to 230F(110C). there’s also 3.5″ of sand in the bottom and plenty of air space between the sides of the bucket and the sand battery. there are many ways to heat the sand.