Abstract: A monogroove heat pipe has a single central manifold communicating with plural parallel connected evaporators and a single condenser. The invention is directed to a tubular screen device which is axially positioned within the liquid channel of the manifold. A number of longitudinally spaced holes are formed in the body of the screen device, each hole being defined by cusp edges which are turned outwardly from the screen body into joint ends of the condenser and evaporator liquid channels. The existence of the screen material at the joint between condenser, evaporators, and the manifold assists the establishment of a primed condition in the heat pipe, even in a zero "g" environment for any initial liquid distribution within the heat pipe.