Newer models of oil furnaces can be converted to natural gas by changing the burner, but some older models can't be converted. The conversion also requires natural gas service to the house.
Converting oil furnaces to natural gas offers several advantages. Oil and propane often require prepayment, but natural gas bills require payment the month after use. Natural gas companies frequently offer customers rebates to change to gas, and sometimes those rebate offers include a new boiler or furnace. Because the majority of the natural gas consumed in the United States is produced in the country, the cost may stay more stable than oil over time.