A heater assembly can be used with a gas appliance. The gas appliance can be a dual fuel appliance for use with one of a first fuel type or a second fuel type different than the first. The heater assembly can include a fuel regulator valve including a main pressure regulator to regulate the fuel pressure, at least one auxiliary pressure regulator, a first fuel source connection for connecting the first fuel type to the heater assembly, and a second fuel source connection for connecting the second fuel type to the heater assembly. The one or more auxiliary pressure regulators introduce a backline pressure to the main pressure regulator, thereby adjusting the fuel pressure to fall within a predetermined range.