Some gas-heated clothes dryers use natural gas while others use liquid propane supplied from a tank. The pressures, heat output and design capabilities of the internal burners are different for the two types of gas. For safety reasons, propane gas dryers are often equipped with a nozzle different in diameter from standard pipe connectors for natural gas. Appliances must also be printed with the burner rating information somewhere on the dryer so you'll know what type fuel to use. If the dryer is already hooked up, check your residential gas supply to find the type.
Close the main gas valve in the house, turning the knob or lever clockwise. If it is connected to a tank at one end and the dryer on the other, your appliance uses liquid propane gas. If you are connected to a public utility, the dryer uses natural gas.
Open the front dryer door to locate the specifications printed inside the door well for the burner. The burner type will be listed as LP if the dryer is designed for propane use. Otherwise, it is a natural gas appliance.
Pull the dryer out from the wall to inspect the gas connection. Locate the 3/8-inch pipe that connects to the rear of the appliance. Above or below this connection may be a label noting whether the dryer uses natural or propane gas.