A T-line is a simple alternative to a pressure tank, air-trap or any other filling, bleeding, and draining device. It is constructed by plumbing a "Tee" connector (tri-barbed, with a perpendicular secondary flow-pattern, shaped like the letter "T") into an existing tube thus creating an alternate flow-path. However, instead of routing the secondary path back into the system flow, it's simply left open or closed off using an end-barb or other capping device. The tube itself thus can act as a min… (More on T-line)