I had no choice but to leave my Keystone from 6 AM to 8 PM yesterday. I threw in a couple of red oak "all-nighters" and some smaller splits, damped down to around 3/4 (the equivalent of about 20% primary air) and I came home to a warm house and LARGE coals to start a new load. That's definitely as far as I have pushed this stove, and I was NOT disappointed! Just thought I'd share.