Monessen Chesapeake 32 Inch Natural Gas Vent Free Fireplace System With Unfinished Mantel. CFX32NVU. Fireplace Mantel Packages. Monessen presents the Chesapeake natural gas fireplace, which features an unfinished mantle that is ready for the paint of your choice. This vent free fireplace system comes ready to assemble with all the tools required for easy installation. This Monessen fireplace system boasts a realistic log set, complete with embers for a natural look to your hearth. The 32-inch firebox is surrounded by a finely crafted mantel. Vent free operation expands your installation options, and the Triple Play Burner System produces 22,000 BTUs of evenly distributed heat. This fireplace system is fueled by clean-burning natural gas.