an advantage of the method of this embodiment is that the wire element can be pre wired on the first layer sleeve prior to installation which can offer flexibility and simplification in manufacturing once wire element 80 has been provided around the first layer sleeve second layer 86 is then applied to substantially cover and preferably completely cover wire element 80 so as to sandwich and encase wire element 80 between the first layer sleeve and second layer 86 second layer 86 may be applied as a sleeve or by spraying with the sleeve form being preferred in this embodiment again it is not important whether second layer 86 is applied prior or subsequent to the installation of the first layer sleeve on the nozzle body second layer 86 if applied in sleeve format is sized to fit as closely as possible over wire element 80 on the first layer sleeve to minimize the air space between the first and second layers a metal outer layer 88 is then applied to the outside of second layer 86 and may be applied by any known means such as by spraying or by shrink fitting a sleeve with shrink fitting a sleeve being preferred in this embodiment again as will be understood by one skilled in the art if a second layer sleeve is used the outer layer may be applied to the second layer sleeve either pre or.