Suburban New SF-30FQ 2391A DUCTED Furnace for RV Camper Motorhome Trailer Furnace 30,000 BTU Suburban SF-30Q Quiet Furnace 12 VDC Ducted 30000 BTU/H Trailer Camper RV Ducted Part# 2391A Electric Ignition 30,000 BTU/H Exhaust and Intake Tube - 3/8" Minimum Open Side Duct Area 36 sq. in minimum number of side ducts used is 3 side duct size 4" Minimum Open Top and Bottom Duct Area 56 sq. in each