I lost power for about 6 hrs today. For me its no sweet because my primary heat is from wood, so I just put a couple extra sticks in and open the damper more than I normally have it; I put an air stone in the tank with a battery driven pump for circulation. I believe I would be good for at least a couple days. I have a generator I would start up if the outage went into night for lights, well, phone... I installed a generax panel I had when we built but didn't have the generator end receptacles at the time and still haven't completed that end of the install. When I get around to getting that complete running the generator will be much simpler.