I think the wife and I have enough bulk coal (anthracite stove size) for 3 years. It is a good feeling to have over 13 tons stockpiled in the barn and not have to worry about keeping warm in the frigid western Massachusetts winters. This past winter we got over 120 inches of snow. The wife and I could not be happier with the Glenwood Base Heater No. 8. It is the best investment we have ever made.