Profile: Dornback Furnace Division is a manufacturer of warm air furnaces, air conditioning equipment and accessories. Our product line includes oil & gas furnaces, infrared heaters, unit heaters, gas burners, oil burners, air cleaners, humidifiers and air conditioners. Our DK-series heater features cordierite-based grooved ceramic tile. Our heater has permeable design with alternating rows of precision perforations terminating in slots.