As you can see in the following table, the E-Classic 1400 furnace holds almost 10 times more wood, has a higher furnace efficiency, and has a higher rated output over 8 hours than the BIS Ultra fireplace. It has certainly been easier to load up the outdoor furnace once a day (or often twice when it's cold). In practice, with our well-insulated house, we typically use the fireplace when it's above freezing outside because the fireplace has enough capacity to keep the house warm. Using the e-Classic 1400 takes longer because of the time it takes to bring all of the furnace's water up to operating temperature and this light load tends to cause creosote build-up. Besides, a crackling fire in the fireplace is nice in the winter.
Although a 32" long log can fit into the firebox, the maximum log length of wood splitter will determine actual log lengths. The dealer who sold me the E-Classic 1400 recommended 24" logs and this seems to be fairly common size for wood splitters too.
| Specification | E-Classic 1400 | BIS Ultra |
| Door | 18.5" x 18.5" | 25" x 14" (glass area) |
| Firebox | 32" L x 24" W x 32.5" H 14.44 ft³ volume |
25"W x 13.5"D x 13"H (nominal) 18"W x 12"D x 12"H (practical) 2.5 ft³ (nominal) / 1.5 ft³ (practical) 18"-19" log |
| Weight | 2,085 lbs. | 402 lbs. |
| Water Capacity | 195 Gallons | N/A |
| 8-Hr Output Rating | 107,459 BTU/hr † (based on dry oak) |
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| 12-Hr Output Rating | 72,000 BTU/hr | |
| Maximum Heat Output Capacity | 209,316 BTU/hr † (based on dry oak) |
up to 60,000 BTU/hr up to 8 hrs burn time |
| EPA Rating | 4.8 grams/hr | |
| Furnace Efficiency | over 84% | 75.2% |
| Note | † Based on EPA qualifying test | tapered firebox is 18" wide at the back |