that is warm be my standards _ -31 + wind chill for a few days this last season. can have week long periods of daytime highs that might get to zero. at any rate I heat a 2200sq ft home with a Englander NC30 , big stove 8-10 hours is no problem and from your original description of your burn that is about how a secondary burn stove tends to run. Cat stoves are capable of giving a more even output of heat over the duration of the burn. So much has to do with level of home insulation and envelope tightness of said dwelling and the overall layout.