Heating elements

Abstract

A water heating element ( 98 ) is disclosed which is in the form of a tube that is open at both ends thereby to form a through passage, wherein the tube comprises a metal outer sleeve and a co-axial metal inner sleeve having an electrically insulating material in the form of ceramic beads or magnesium oxide powder therebetween with electrical resistance wires running through the insulating material. The element ( 98 ) is mounted in an inclined position in the hot water cylinder ( 102 ) with the open lower end of the element close to the bottom wall of the hot water cylinder.

1 . A heating element in the form of a hollow tube defining a passage, the passage being open at both ends so that water can flow through the tube from an inlet end of the passage to an outlet end of the passage. 
     
     
         2 . A heating element as claimed in  claim 1 , wherein the tube comprises inner and outer shells with a resistance wire between the shells. 
     
     
         3 . A heating element as claimed in  claim 2 , wherein said outer shell comprises an elongate outer metal sleeve and a cylindrical liner of electrically insulating material inside said outer metal sleeve, and the inner shell comprises an elongate inner metal sleeve and a cylindrical sheath of electrically insulating material on the outside of said inner metal sleeve, said resistance wire being in a space between said sheath and said liner. 
     
     
         4 . A heating element as claimed in  claim 3 , wherein the metal sleeves are of copper and the liner and sheath are of ceramic material. 
     
     
         5 . A heating element as claimed in  claim 3  and including end rings for closing both ends of said space in which said resistance wire is located. 
     
     
         6 . A heating element as claimed in  claim 1  and including, at one end of the tube, a structure for mounting the tube on the wall of a hot water cylinder, the structure including passageways for electrical leads connected to said resistance wire. 
     
     
         7 . A heating element as claimed in  claim 6 , wherein said structure includes a block having bores through it, said bores constituting the passageways for said leads. 
     
     
         8 . A heating element as claimed in  claim 7 , and including metal tubes secured to said block and to one or other or both of said sleeves, said leads passing through said tubes. 
     
     
         9 . A heating element as claimed in  claim 1 , wherein said tube comprises an outer metal sleeve and an inner metal sleeve with side-by-side beads between the sleeves, each bead having a central opening through which said inner metal sleeve passes and a plurality of further openings through which the resistance wire passes. 
     
     
         10 . A heating element as claimed in  claim 1 , wherein said tube is constituted by an elongate metal sleeve with at least one resistance wire within the sleeve and extending along it, there being electrically insulating material within the sleeve for electrically isolating said resistance wire from the sleeve, said sleeve being wound into the form of a hollow coil with a plurality of turns, said passage being bounded by the turns of the coil. 
     
     
         11 . A heating element as claimed in  claim 10 , wherein adjacent turns of the coil touch one another. 
     
     
         12 . A heating element as claimed in  claim 1 , in which the passage has therein a component which reduces the area of the passage over the length of the component. 
     
     
         13 . A heating element as claimed in  claim 12 , wherein said component is at one end of said passage. 
     
     
         14 . A water heater comprising a block for mounting the heater on the mounting plate of a hot water cylinder, an elongate mounting element protruding from said block, the element having a bend in it so that it has a first portion extending from said block and a second portion which is at an angle to said first portion, and a water heating structure including a resistance wire connected to said second portion of said element. 
     
     
         15 . A water heater as claimed in  claim 14 , wherein, when said first portion is horizontal, the second portion is at an angle of 30 to 60 degrees with respect to the horizontal. 
     
     
         16 . A water heater as claimed in  claim 15 , wherein said angle is between 40 and 50 degrees. 
     
     
         17 . A water heater as claimed in  claim 14 , wherein said element is in the form of a tube. 
     
     
         18 . A water heater as claimed in  claim 14 , wherein said element is constituted by a pair of parallel tubes. 
     
     
         19 . A water heater as claimed in  claim 17 , wherein electrical leads extend through said tube or tubes and are connected to said resistance wire. 
     
     
         20 . A water heater as claimed in  claim 14 , and including a pocket for a thermostat, the pocket being externally threaded over an end portion thereof and the mounting block having an internally threaded bore through it into which said pocket can be screwed. 
     
     
         21 . A water heater as claimed in  claim 20 , wherein said pocket is above said first portion. 
     
     
         22 . An installation comprising, in combination, a hot water cylinder having a mounting plate and a water heater as claimed in  claim 14 , said block of the water heater being secured to the mounting plate with said first portion protruding into the cylinder and said second portion and said heating structure extending downwardly from said first portion towards the bottom of the cylinder. 
     
     
         23 . A heating element as claimed in  claim 1  and including a mounting structure for the heating element, the mounting structure having a bend in it so that when the mounting structure is secured to a vertical wall of a hot water cylinder, the heating element slopes down from said wall.