A dual fuel heater can couple with one of two fuel sources operating at different pressures. The dual fuel heater can have a first fuel line, a second fuel line, a fluid flow controller, and a combustion chamber. The fluid flow controller can selectively permit flow of a first fuel to either the first fuel line or flow of a second fuel to the second fuel line. The first fuel line can be in communication with a first oxygen depletion sensor orifice and the second fuel line can be in communication with a second oxygen depletion sensor orifice.