Winchester gas furnaces are natural gas ready and convertible to LP gas with the installation of an optional LP 347 conversion kit, which is necessary to adjust for the pressure difference between the gases. Kits are available online from Home Depot or Lowe's.
Conversion of fuels requires replacement of the burner orifices, gas valve spring and low gas pressure switch. Gas pressure must be adjusted by a certified technician. BuildWithPropane.com provides a listing of federal, state and local incentives available for installing propane furnaces. Manufacturers state that propane furnaces last five to ten years longer than electric furnaces, giving longer payback on equipment.