Abstract: A hot runner molding manifold has a first half having flow grooves, a cover piece having flow grooves complementary to the flow grooves of the first half, and a second half securable to the first half and having a cavity for receiving the cover piece. The flow grooves of the first half and the cover piece form flow channels for distributing molten material from an inlet port to outlet ports. The cover piece is engaged with the first half, for example by welding, to reduce leakage of molten material out of the flow channels. Heater grooves in the first half, second half or both the first and second halves receive one or more heating elements for heating the flow channels.