There are three common fuel sources for patio heaters: liquid propane, natural gas, and electricity. To figure out which is right for you, think about what’s most readily available, convenient, and affordable. Many heaters are powered by 20-pound liquid propane tanks, as the fuel is quite affordable, but you’ll have to refill your tank, which typically entails taking a trip to a local convenience store, gas station, or home improvement store. If that sounds like a hassle, you may want to opt for an electric model, which simply plugs into a standard 120-volt outlet. Just be aware that frequent use of an electric patio heater may increase your electricity bill. Natural gas is another option, but it's only practical if you already have a natural gas line installed in your home.