A header insert for an evaporator header outlet port of an evaporator header, comprising: a header insert body that extends along a body center axis between a body inlet end and a body outlet end, wherein the header insert body includes a center passage defined by a center passage surface located within the header insert body, the center passage surface extending from the body inlet end to the body outlet end along the body center axis, the center passage surface defining: a center passage inlet portion at the body inlet end; a center passage outlet portion at the body outlet end, the center passage outlet portion defining a body nozzle portion on the body center axis, the body nozzle portion having a convergent-divergent shape so that the body nozzle portion has a convergent segment, a divergent segment and a neck segment therebetween; a conical tip member, fixed to the body outlet end and disposed at least partially within the divergent segment of the body nozzle portion so that a conical outlet passage is formed therebetween; and a flange that extends radially outwardly from the header insert; characterised in that the flange extends radially outwardly from a location that is axially between the body inlet end and the body outlet end; wherein the center passage outlet portion of the center passage surface is axially between the flange and the body outlet end. a header insert body that extends along a body center axis between a body inlet end and a body outlet end, wherein the header insert body includes a center passage defined by a center passage surface located within the header insert body, the center passage surface extending from the body inlet end to the body outlet end along the body center axis, the center passage surface defining: a center passage inlet portion at the body inlet end; a center passage outlet portion at the body outlet end, the center passage outlet portion defining a body nozzle portion on the body center axis, the body nozzle portion having a convergent-divergent shape so that the body nozzle portion has a convergent segment, a divergent segment and a neck segment therebetween; a conical tip member, fixed to the body outlet end and disposed at least partially within the divergent segment of the body nozzle portion so that a conical outlet passage is formed therebetween; and a flange that extends radially outwardly from the header insert; characterised in that the flange extends radially outwardly from a location that is axially between the body inlet end and the body outlet end; wherein the center passage outlet portion of the center passage surface is axially between the flange and the body outlet end. a center passage inlet portion at the body inlet end; a center passage outlet portion at the body outlet end, the center passage outlet portion defining a body nozzle portion on the body center axis, the body nozzle portion having a convergent-divergent shape so that the body nozzle portion has a convergent segment, a divergent segment and a neck segment therebetween; a conical tip member, fixed to the body outlet end and disposed at least partially within the divergent segment of the body nozzle portion so that a conical outlet passage is formed therebetween; and a flange that extends radially outwardly from the header insert; characterised in that the flange extends radially outwardly from a location that is axially between the body inlet end and the body outlet end; wherein the center passage outlet portion of the center passage surface is axially between the flange and the body outlet end.