Temperature-responsive controller for waterbed mattress heaters

In combination:

• a waterbed structure including a horizontal platform, a retaining frame about the perimeter of and projecting up from the platform, a soft, flexible sheet plastic bladder mattress containing a volume of water supported atop the platform and within the frame;
• an electric resistance heater engaged with and between the platform and the mattress to heat and maintain the mattress and the water therein, an elongate power cord with a pair of conductors connected with and extending between the heater and an electric power service outlet remote from the waterbed structure, the cord has an inner portion extending from the heater between the mattress and the platform and between the mattress and the frame, and has an outer portion extending freely from said bed structure to said service outlet;
• a manually- adjustable thermally-responsive temperature controller responsive to the temperature of the mattress and operating to start and stop the flow of current through the cord, said controller includes an elongate cylindrical housing with opposite ends, an adjustable on and off switch with relatively movable contact parts within the housing, a manually-engageable adjusting knob accessible at one end of the housing with a shaft entering and sealingly-engaged in the housing, said shaft has a switch-adjusting part engaged with one movable contact part of the switch, a fluid-filled Bourdon tube mounted within the housing and engaging and moving another movable contact part of the switch relative to said one movable contact part between opened and closed positions when the Bourdon tube is deflected by changes in fluid pressure therein, an elongate fluid-filled capillary tube with an inner end connected with the Bourdon tube and an outer end portion extends from within and is supported by the exterior of the housing, openings in the housing into and out of which the capillary tube and related ends of the inner and outer portions of the power cord extend, conductors of the portions of the power cord are connected with related terminal parts of said switch, the controller housing is positioned in supported engagement between an inside surface of said frame and an adjacent portion of said mattress with a portion of the capillary in heat-conducting contact with the mattress.