Hot water tank flex lines
 

Manufactured home has a black nylon covered flex line (from Home Depot) on the cold nipple and a regid galvanized line on the hot nipple.
CAN I USE A black nylon flex on the HOT nipple?

I know manufactured homes use different standards . . . My preferred application would be a braided metal over the flex line for both hot and cold using "shark bite" attachments. If not, then I would use flex copper with standard threaded connectors.

I wonder if your entire home is piped with PEX? Their system uses red for hot and blue for cold.
http://www.pexinfo.com/#advantages