The EPA has several test methods for the testing of wood burners. They are giving the manufacture and option of which methods to use. Plus many states have there own test methods or differences in the test methods. Using Cord Wood may be the EPA's way of letting the manufactures of shooting them selves in the foot. From my wood burning experience different types of wood burn different and would generate different results. Most likely resulting in bad emisson results and giving the EPA a reason to shut us down or implement more control.