Furnace maintenance Check operation, check combustion numbers 6.5% oxygen and 16ppm carbon monoxide, check for gas and co leaks, checked fan capacitor 25mfd, check amp draws on the fan 4.3 and the inducer motor.5amps, check static pressure .4inwc on the supply .2inwc on the return, checked safety limits and pressure switches, check igniter and heat exchanger, cleaned flame sensor and burners, cleaned pressure ports and Venturi hose, customer changes his own filter, tested operation. Recommend keeping up on maintenance and looking into an air purifier and possibly a maintenance free up t0 7 years water filtration system.