A hardware configuration and related method for straight injection molding of ophthalmic lenses using thermal control fluid circulating within a closed channel located interior of the insert. The channel is closed by a no-leak valve. The adjusting body is equipped with a mating no leak valve. The valves seal over an operational distance L before the valves are opened to admit the thermal circulating fluid into the insert. The insert can be easily changed or shimmed without leaking and without having to change the insert configuration.