Furnace maintenance in Dacula, Georgia. Three systems. Did not change filters. Dusted out furnace cabinets, cleared barometric tubing. Cleared upstairs drain line. Tested mechanical and electrical components. Found upstairs system with dirty blower wheel, recommend blower wheel pull and clean. Found flexible gas line inside basement furnace, this is not up to code as code requires hard pipe to be inside of furnace as a safety precaution, recommend moving flex gas line so all of it is outside furnace and only hard pipe is inside furnace. Basement system has no water safety whatsoever, recommend water safety switch to shut off system as a safety in the event of a backed up drain line or frozen coil leaking water. Moved flexible gas line outside of basement furnace and put hard pipe in. Installed wet switch for basement system. Systems are heating at this time.