I was thinking of getting a Mr. Heater unit for emergency use as well, but one thing that I wasn't sure about is the fact that it says not to use it indoors with a 20# tank. Why is it unsafe to use the bulk tank indoors while it's fine to use the 1# tanks?

Also when the power goes out and your dealing with outside temps of 0deg. or colder wouldn't having a window open negate the use of the smaller (like Mr. Heater Buddy) heaters? I was planning on using it in the central room of the house and having blankets up over entrances to the other rooms to conserve the heat, but I don't want to put my family in any danger.