Complete 2 system furnace repair and preventative maintenance check. Found upstairs unit with UV light surge protector and secondary water switch. Blower wheel is clean all electrical components are good and system heating good. Basement system is heating good with clean blower wheel and working electrical components however system has no secondary water safety device or surge protector. Also system has no air purifier device installed. Recommend all 3 to better protect system,house, and residents.