fermentation box

Why would you want to heat your beer? I just make sure I only brew lagers in the colder months and ales and steamers in the warmer months. I know a lot of the kits in Australia tell you to keep the temp between 18 and 25 degrees Celsius but it really does not need to be anywhere near that high, especially for lagers. I brew most of my lagers at around 8-10 degrees, the fermentation takes longer but that doesn't matter....

If you want to brew ales in winter just build a square box with not much empty space in it, the best system I ever saw was a large plastic container that the fermenter fitted inside, the space was filled with water and that water was kept at the correct temperature with an immersion heater. The beauty of this was that the heater didn't need to be washed every time it was used.