Abstract:
An improved, full hot air recovery, fireplace-heater is disclosed, wherein the flue gases are forced to follow obliged paths through exchange chambers before being exhausted to the outside. The fireplace comprises a hearth and a plurality of chambers for the circulation of flue gases, which are serially arranged one another on the exterior of the hearth and surrounded by an outer chamber for the circulation of ambient air where the flue gas heat is recovered by exchange at walls. Also provided is a means for forcing the circulation of ambient air through the chamber.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a fireplace-heater with full recovery of hot air. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a fireplace or heater which can recover the largest possible amount of heat which would otherwise be lost with the flue gases. 
     A consequent important object is to provide a structure wherein the flue gases, prior to being exhausted, are obliged to follow definite paths through exchange chambers. 
     A further object is that of providing a simple modular structure which can fit fireplaces with different outward shapes. 
     These and other objects, such as will be apparent hereinafter, are achieved by a fireplace-heater with full recovery of hot air, comprising a hearth and at least one smoke chamber, characterized in that it has a plurality of smoke chambers serially arranged on the exterior of said hearth, said chambers being in turn enclosed in an outer ambient air circulation chamber for recovering heat from the flue gases by thermal exchange at wall members, a means being also provided to force said circulation of ambient air. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further features of the invention will be more clearly apparent from the following description of an embodiment thereof with reference to the accompanying illustrative drawings, where: 
     FIG. 1 is a partly sectional perspective view of a space heater according to the invention; 
     FIG. 2 is a midsection view schematically illustrating the circulation path of the flue gases relatively to the space heater of FIG. 1; 
     FIG. 3 shows a second diagram of the flue gas circulation path in a modified embodiment with respect to the heater of FIGS. 1 and 2, the view being taken on a front midplane of the heater; and 
     FIG. 4 shows a sectional view of the heater of FIG. 3, as taken on a parallel plane to the side face thereof. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Making reference to the drawing figures, a space heater according to the invention comprises an outer enclosing body or casing of glazed ceramic material, indicated at 1 and enclosing a metal structure, specifically a cast iron one, which comprises a brazier 2 closed at the front by a door 3 having a glass window 31 and being fed with combustion air through a slotted grid 4 located on the front wall of the outer body 1, under the door 3 and above an ash collecting tray 5. Said brazier forms the bottom portion of a combustion chamber 6 defined laterally by first vertical sidewalls 7 and at the top by a substantially horizontal ceiling 8. Said first walls 7 extend at the bottom from the brazier 2 but end short of the ceiling 8 to leave a top side opening 49 for the passage of the flue gases. 
     Said first walls 7 and said brazier 2 define a first U-shaped wall structures with vertical wing portions coinciding with the walls 7 and a horizontal web portion coinciding with the brazier 2. 
     The ceiling 8 is connected laterally to second vertical walls 9 arranged parallel outside of the walls 7 and forming therewith a first chamber or interspace passage 50 swept by flue gases in a downward direction, as shown by the arrow 10. The ceiling 8 and the second sidewalls 9 define an inverted U-shaped wall structure with vertical wing portions conciding with the second sidewalls 9 and a horizontal web portion coinciding with the ceiling 8. Additional sidewalls 15, located outside of the walls 9, form with the latter a second chamber 51 swept by flue gases in an upward direction, as shown by the arrow 11. Also the sidewalls 15 are part of a U-shaped wall structure with a pair of opposite vertical wings and a horizontal web portion connecting the wings at their lower end. If desired, to reverse the flue gas flow direction, there may be provided a baffle 12 located at a distance away from the bottom edges of the walls 9 so as to create a bottom side opening 52 and force the flue gases to reverse their direction as shown by the arrow 13. 
     Provided above the ceiling 8 is a chamber 53 whereinto the flue gases from the chamber 51 are directed and which is connected directly to a chimney union 14. 
     Externally to the walls 15, there is formed, by means of a parallel sector 16, an air passage vertical chamber 17 which is connected at the top to an interspace 18 the base 19 whereof provides separation from the upper flue gas chamber 53, the interspace 18 being in communication at the top with the ambient air through a grid 20. The parallel sector 16 is also in the form of a U-shaped wall structure with vertical wings and a horizontal web portion connecting the lower ends of the wings. 
     The vertical chamber 17 is connected at the bottom to an intake chamber 21 which is connected to the suction side of a ventilating unit 22 the delivery side whereof opens, through flexible hoses 23, to grids 24 located in the lower portion of the outer enclosing body 1. 
     The path of the ambient air forced by the ventilation unit 22 is shown by the intake arrows 25 which are continued by the downward flow arrows 26 and hot air ejection arrows 27. 
     In practice, the hot flue gases generated by the combustion on the brazier 2 rise toward the upper portion of the combustion chamber 6 and flow downwards along a first downward flow path, to then flow again upwardly toward the chimney, thus delivering their heat to the wall assembly, which are all formed from good heat conducting materials, such as cast iron. 
     The ambient air is instead picked up from above and sweeps the walls heated by the flue gases in countercurrent relationship to then exhaust downwardly back to the ambient. 
     FIGS. 3 and 4 show a second embodiment of the invention which incorporates modifications to the flue gas circulation and ambient air chambers. 
     With reference to the latter figures, the invention comprises here a hearth 101 forming the combustion chamber and having a substantially box-like shape with side and rear walls 102, a glass front access door 103, hearth bottom with a grid 104, and top flue gas exhaust opening 105. 
     Said top opening 105 communicates with a first inverted-U chamber 106 which is closed at the bottom by a partition 107, whereat it has a peripheral opening 108 communicating with a second enveloping chamber 109 open to the outside at its lowermost portion. 
     The partition 107 spans partially also said second chamber 109 to form a baffle. 
     In its upper portion, said second chamber 109 has an opening 111 which communicates with a third chamber 112 in communication with the chimney 113. 
     The assembly formed by said three chambers 106, 109 and 112 is contained within an outer chamber 114 provided at the top with a grid 115 and at the bottom with a connection 116 with a forced ventilation unit 117. 
     The flue gases 118 generated by the combustion supported by outside air 119 as indicated by the dashed arrows and in turn indicated by full line arrows move upwards toward the top opening 105, whence they flow down into the first chamber 106 as far as the partition 107, whereat they reverse their direction to flow up into the second chamber 109. 
     The provision of the baffle 107 which spans partly the chamber allows the outside air indicated by the dash line arrows to become mixed with the flue gases from said first chamber 106. The baffle 107, by narrowing the section of the chamber 109 creates a Venturi effect which accelerates the flue gas speed of upflow, said gases, on leaving through the opening 111, flowing into the third chamber 112 and hence out through the chimney 113. 
     The ambient air indicated by the dash-and-dot arrows is sucked in countercurrent relationship through the openings 150 and sweeps the hot chamber exteriors to be returned to the ambient by the ventilating unit 117. 
     The walls of the various chambers 106,109 and 112, which are formed from good heat conductive metal materials, provide a means for transferring the heat from the flue gases to the outer chamber which receives the ambient air. 
     The lengthened flue gas path enables the achievement of the highest rate of heat exchange, thereby the flue gases will reach the chimney at a significantly low temperature but sufficient to ensure their ejection to the outside. 
     The ambient air sucked in in countercurrent relationship from above is heated, thus recovering a large amount of heat which is then returned to the ambient.