How does this SunStar Corcho Model SC-18 heater work again? (Applies to Manual ONLY)

It’s slightly different than some 3-plaque heaters you may have seen previously. Instead of turning on the pilot and then one, two, and three plaques, the SunStar Model SC-18 uses just two burner chambers and operates first on the single plaque burner. After the single plaque comes on, the double plaque is turned on – giving you three full plaques of operation. If only two plaques are needed, then the double plaque burner may shut off leaving just one plaque burning.