Abstract: A fuel-fired water heater is provided with a flame spreader-type fuel burner assembly that reduces the operating NOx emissions of the water heater. The assembly includes a radial port gas burner coaxially disposed in a facing relationship with a generally inverted dish-shaped flame spreader which intercepts and is impinged on its concave side by the burner flames. In various disclosed embodiments of the flame spreader, during operation of the burner the burner flames pass through spaced series of openings extending through the flame spreader body inwardly of its outer edge periphery instead of being deflected horizontally outwardly past such periphery before passing upwardly beyond the flame spreader. The passage of the previously generated burner flames through these various openings serves to materially reduce the burner NOx emissions compared to a burner having an associated flame spreader with a conventional imperforate construction.