They were not rated by BTU since wood species across the country would vary widely.
Keep in mind they were designed in an area where there is soft woods only.
Fisher literature for Mama Bear stated; " Heats Approx. 1500 sf " or " up to 1750 sf " or " 1250 - 1750 "
Here's one of many calculators; https://www.hearth.com/econtent/index.php/articles/burn_time_calculator
Keep in mind they were designed in an area where there is soft woods only.
Fisher literature for Mama Bear stated; " Heats Approx. 1500 sf " or " up to 1750 sf " or " 1250 - 1750 "
Here's one of many calculators; https://www.hearth.com/econtent/index.php/articles/burn_time_calculator