I have an Englander 25-pdv installed in my basement of my brick ranch (1100sq ft basement) with 1300 upstairs finished. Running it at +1 setting it heats basement to 70-72deg. And I get 23-24hrs to a bag. I don't really believe I get to much heat upstairs ( stairway door open) and if I increase heat setting it drops 2-3hrs per # increase. I believe stove is operating ok. Is an OAK really required and what are my problems running without? Thx