Boiler To Forced Air Conversion . Radiant systems provide better indoor air quality than forced air systems. Budget $7500 to $15,000 plus the cost of the heating equipment, depending on the complexity of the ductwork installation, including refinishing damaged areas of your home's walls and ceilings. Oil to Gas Furnace Conversion Time to Convert Your Oil Furnace to a from www.eheatcool.com This will usually cost ~$5,000 per 1000 square feet of living space. One easy solution is the installation of the carlin gas conversion burner that can be installed in almost any oil fired furnace, boiler or water heater. Even when the register must be replaced, front wall pressure parts are usually not required to convert a coal or oil burner to natural gas (figure 1).