burning the user and yet affords good heat transfer from an external heating element into the water in the tank it provides as an insert in the plastic tank a tubular metal heat transmission member with special sealing means between the plastic and the ends of the metal member the sealing means prevent leakage from the container around the ends of the metal member that could result from differences in expansion rates of the plastic and the metal application_number US 85021177 A description referring to fig4 and 5 a typical front wall of the machine includes a panel 10 having a main starting switch 11 thereon it also has a metal spring clip 12 having a latching member 13 projecting therefrom the spring clip is attached to the front panel by screws 14 the clip has its end bent outwardly and has a latching shoulder 16 the panel also has three positioning buttons 20 21 and 22 firmly secured to it and projecting a short distance forwardly it also has a thermostatic adjustment 24 projecting from it the latter projecting only so far as the positioning buttons 20 22 project a generally cylindrical heating element 27 projects forwardly from the front wall of the panel 10 in the illustrated example it is approximately 5 8 of an inch in diameter the plastic tank or receptacle generally indicated at 30 is preferably box.