Oil furnaces burn heating oil, which is similar to diesel, while gas furnaces use natural gas. Heating oil is delivered by truck to each customer and stored in an aboveground storage tank. Natural gas customers are hooked up to the local gas company lines.
According to the U.S. Energy Information Administration, the oil option tends to be more expensive. A comparison survey in the winter of 2012 to 2013 showed that oil furnaces cost roughly $2,558 to run per home, while natural gas averages $690 per home. Prices for both fluctuate, depending on the supply and market price.
Oil furnaces are considered less efficient than gas, usually getting an annual fuel utilization efficiency rating of between 80 and 90 percent. Gas furnaces regularly score between 89 and 98 percent. That means the gas furnaces leave less waste behind when burning fuel to create heat.
Gas furnaces tend to be 10 to 20 percent more expensive than the oil models, but oil models need a fuel tank to be purchased and installed. Since an oil furnace burns fossil fuel, soot tends to build up in the chimney and clog the air filters. Oil delivery companies usually offer maintenance contracts, which is the easiest way to keep the furnace running smoothly. Gas furnaces tend to be quieter and not need as much maintenance.