Gas heating preventative maintenance performed Check filter - 16x20x1 Clean flame sensor Ohm test igniter: 48.4 Inspect wiring for loose connections and/or hot spots - Check humidifier pad: N/A attic Inspect exhaust flu - no leaks / no concerns Set thermostat for heat Check delta T - 45° Furnace is in optimal running conditions Furnace filter door will pull up and off.