I am working on the details of the cooling system and have the pressurized "Header" tank worked out. In looking at the overflow tank, I have a -4AN fitting going to a 1/8th NPT at the top of the tank, and a drain at the bottom. Shouldn't there be a hose connected to the NPT thread going to the bottom of the overflow tank in order to allow for the return of coolant when the system cools down? If so, where is the source for that tubing?