Harman Serenity II Gas Fireplace Specifications Fuel Natural Gas or Propane BTU Range High - 31,000 Low - 21,000 (Natural Gas or Propane) Depth 16-3/8 inches Height 41-15/16 inches Width 36-7/8 inches Testing ANSI Z21.88-1998-CSA 2.33-M98 CAN/CGA-2.17-M91