Furnace tune up in Lawrenceville, Georgia. Two systems. Found upstairs system with no filter inside, put filter inside. Tested mechanical and electrical components. Found both systems with no water safety so it is therefore not up to code. Found upstairs furnace with worn igniter. Found upstairs furnace with weak flame safety sensor. Found upstairs blower capacitor to be weak. Found upstairs blower wheel to be dirty. Found upstairs ductwork to be dirty. Found upstairs evaporator coil to be dirty. Found upstairs evaporator coil to be rusty and corroded and likely to leak. Upstairs ductwork is not of r8 insulation rating. Found downstairs blower capacitor to be weak. Found downstairs blower wheel to be dirty. Found downstairs igniter to be worn. Found intermittent issue with downstairs gas valve failing, either gas valve is going bad or control board is. Both systems are 16 years old. Due to age and condition of both systems, recommend upgrading systems to more reliable, more efficient s