The Rheem FP-34 LP Conversion Kit allows for a simple conversion of a natural gas furnace to a LP (Propane) installation. Assure only to use the following conversion kits on the furnace model and gas control systems for which they are shown in the Rheem LP Conversion Chart. Do not substitute kits or kit components. The first two letters of the serial number designate the control system as applied by the manufacturer and the type gas it was manufactured to burn. All furnaces are manufactured to burn natural gas, conversion kit required if changing fuel type.