Traditional: Open face with damper and spark screen. Optional glass doors of many varieties may be used. These units will give off radiant heat but aren’t very efficient. Most jurisdictions in Colorado’s high country do not allow these units to be installed without converting to gas log system.
EPA Certified: Very efficient wood burning fireplaces with doors that seal. Can be burned in almost all areas of Colorado without restrictions. Usually uses a catalytic combustor to burn off waste/smoke for clean burn. Has a smaller firebox than traditional units but will burn much longer due to being able to control combustion air.