dᵻpˈɛndɪŋ ɔnðɪ ˈeɪdʒ ʌvðə sˈɪstəm, fˈoːɹstˈɛɹ ɡˈæs fˈɜːnɪsᵻz jˈuːs ˈiːðɚɹ ɐ pˈaɪlət lˈaɪt ɔːɹ ɐ sˈɑːlɪdstˈeɪt ɪɡnˈɪʃən sˈɪstəm spˈɑːɹk ɔːɹ hˈɑːt sˈɜːfɪs ɪɡnˈɪʃən tə lˈaɪt ðə nˈætʃɚɹəl ɡˈæs bˈɜːnɚ.
Depending on the age of the system, forced-air gas furnaces use either a pilot light or a solid-state ignition system (spark or hot surface ignition) to light the natural gas burner.