Due to the configuration of our house and lot, we have very limited access to our back yard. There's about 3 feet between our garage and a small stream on the one side, and at most, 4 feet between the house and a significant drop off on the other side. I'm pretty sure we can't get an OWB into the back yard. However, I came across the Aqua-Therm Unsheltered Wood Boilers. It looks to me like it's basically the guts of an OWB, but you can install it in an existing building (wood shed, detached garage, etc). First, I'm curious to get any and all opinions on the Aqua-Therm line of products. Second, does this sound safe to all of you? The last thing I want is to burn down my garage in the name of saving money on heat. How hot do these things get and how much in the way of sparks come shooting out when you open the door to refuel? Just the idea of a fire burning in the garage (even though it is contained inside the unit) while the gas for the lawn mowers, weed wackers, chain saw, etc is in there makes me a little nervous. Justified?