The disclosure relates to a heat exchanger including an evaporator with a pair of base plates, each base plate having a first surface with channels extending from a manifold at a first end of the evaporator to a manifold at a second end of the evaporator, some of the channels are embedded into the base plate and some of the channels are arranged outside of base plate, a condenser with channels extending from a manifold at a first end of the condenser to a manifold at a second end of the condenser, at least one riser pipe and at least one return pipe.