I have a Pacific Energy Summit LE model. At the time of purchase, the specifications indicated a Firebox Size of 3.0 cu.ft., with a heating capacity of up to 3000 sq. ft. Nevertheless, after re-checking four years later, the firebox size is now stated to be 2.5 cu.ft. Can you explain the reduction in firebox size? Is the unit still able to heat areas up to 3,000 sq. ft.?