Patent Publication Number: US-2017363300-A1

Title: Furnace with Manifold for Controlling Supply of Heated Liquid to Multiple Heating Loops

Description:
This invention relates to a furnace and particularly to a manifold for the furnace which provides connections for two or more liquid loops or drops each for providing heating through a separate heat exchanger to a separate area to be heated, where the manifold is arranged to control the supply of heated liquid from the furnace to the separate heating loops. There may be only two loops or more loops depending on capacity and requirements. 
     The arrangement herein provides a simplified form of manifold which can be mounted in the circuit in which the liquid, typically water, is heated in the heat exchanger of the furnace in order to supply the heated water to two or more loops. 
     The arrangement herein is particularly well suited for outdoor wood furnaces or any exchanger where multiple buildings are heated. 
     SUMMARY OF THE INVENTION 
     According to the invention there is provided a furnace for heating a heat transfer liquid comprising: 
     a furnace heat exchanger having a heated liquid outlet and a cooled liquid return so that cooled liquid returned to the return passes through the furnace heat exchanger to be heated and discharged through the heated liquid outlet; 
     a heating system in the furnace for applying heat to the furnace heat exchanger to heat the liquid; 
     a furnace pump for pumping the liquid in a circuit through the furnace heat exchanger; 
     a manifold connected in the circuit between the liquid outlet and liquid return; 
     the manifold having a heated liquid inlet for receiving the heated liquid from the heated liquid outlet and a cooled liquid outlet for supplying cooled liquid to the liquid return; 
     the manifold having a plurality of discharge openings and a plurality of return openings; 
     the discharge openings being collected in adjacent positions in a first area of the manifold and the return openings being collected in adjacent positions in a second area of the manifold with the first and second areas being connected by a transfer area of the manifold for transfer of liquid therebetween; 
     each discharge opening being associated with a respective return opening for connection to a respective supply loop including a respective loop pump and a respective output heat exchanger for heating a respective zone with liquid being extracted from the manifold by the loop pump through the respective discharge opening and returned to the respective return opening; 
     the heated liquid inlet of the manifold being connected to the manifold in the first area with the plurality of discharge openings at a position between the plurality of discharge openings and the plurality of return openings. 
     In a preferred arrangement there is provided a bypass in the circuit for liquid to bypass the manifold together with a temperature controlled protection valve connected between the bypass and the manifold, the valve being operated to control flow between the manifold and the bypass such that when liquid at the cooled liquid return is below a predetermined temperature the valve operates to halt passage through the manifold and, as a temperature of the liquid increases, the valve is opened to allow passage through the manifold dependent on the increasing temperature. In other words, when the liquid at the cooled liquid return is below the predetermined temperature the valve operates to halt passage from the manifold and, as the temperature of the liquid increases, the valve is opened to allow passage through the manifold back to the furnace dependent on the increasing temperature. 
     This arrangement therefore tends to reduce the amount of heated liquid available to be transferred to the separate loops. However the loops each include their own separate pump so that the amount of water passing through each loop remains typically at a constant value. The manifold therefore provides a compensation arrangement where some of the water returned by the loop must pass to the discharge opening to that loop since insufficient water is available from the circuit within the furnace. 
     In addition the arrangement herein can provide the possibility for the total volume of liquid pumped through the loops to be different from the volume passing through the circuit. Typically the volume passing through the loops is less than the available liquid from the circuit. However in some cases the available volume from the circuit may be less than that which is taken by the loops. 
     Preferably the heated liquid inlet of the manifold is connected to the manifold in the first area separate from the transfer area between the plurality of discharge openings in the first area and the plurality of return openings in the second area. In this way cooled water returning from the loops to the return openings of the manifold access the heated liquid entering the heated liquid inlet to mix with that heated liquid before the mixed liquid reaches the discharge openings. This prevents a mode of operation in which one of the discharge openings to one of the loops receives more heat than the other or others of the discharge openings. In this way the heat available in the heated liquid is balanced between each of the loops. 
     Preferably the cooled liquid outlet is connected to the transfer area. 
     As stated above in many cases the sum of volumes pumped by the loop pumps is different from a volume pumped by the furnace pump. 
     The arrangement is particularly effective where a sum of volumes pumped by the loop pumps is greater than a volume pumped by the furnace pump and allowed to pass through the manifold by the protection valve. 
     Preferably the protection valve is connected between cooled liquid outlet of the manifold and the bypass and the protection valve controls discharge of liquid from the cooled liquid outlet of the manifold. In this arrangement preferably the protection valve is connected to the manifold at the transfer area. 
     In a particularly effective arrangement the manifold comprises a chamber divided longitudinally by a transverse wall into the first area on a first side of the wall and the second area on a second side of the wall and wherein the transverse wall terminates at one end at a position spaced from an adjacent end of the chamber to define an undivided portion of the chamber at said end which forms the transfer area. 
     In this arrangement the heated liquid inlet of the manifold is preferably arranged on one side the transverse wall in the first area. 
     While other shapes can be used, preferably the chamber is rectangular in cross-section to define four walls at right angles with the discharge openings in a first wall and the return openings in a second wall. 
     Where the chamber is rectangular, preferably the discharge openings are located in a first wall and the return openings in a second wall at right angles to the first wall with the transverse wall arranged diagonally to the first and second walls. In this arrangement preferably the heated liquid inlet is located in a third wall and the cooled liquid outlet is in a fourth wall. 
     Preferably there is a transfer channel for the heated liquid along the third wall for carrying the heated liquid to the inlet therein. 
     According to a second aspect of the invention there is provided a furnace for heating a heat transfer liquid comprising: 
     a furnace heat exchanger having a heated liquid outlet and a cooled liquid return so that cooled liquid returned to the return passes through the furnace heat exchanger to be heated and discharged through the heated liquid outlet; 
     a heating system in the furnace for applying heat to the furnace heat exchanger to heat the liquid; 
     a furnace pump for pumping the liquid in a circuit through the furnace heat exchanger; 
     a manifold connected in the circuit between the liquid outlet and liquid return; 
     the manifold having a heated liquid inlet for receiving the heated liquid from the heated liquid outlet and a cooled liquid outlet for supplying cooled liquid to the liquid return; 
     the manifold having a plurality of discharge openings and a plurality of return openings; 
     the discharge openings being collected in adjacent positions in a first area of the manifold and the return openings being collected in adjacent positions in a second area of the manifold with the first and second areas being connected by a transfer area of the manifold for transfer of liquid therebetween; 
     each discharge opening being associated with a respective return opening for connection to a respective supply loop including a respective loop pump and a respective output heat exchanger for heating a respective zone with liquid being extracted from the manifold by the loop pump through the respective discharge opening and returned to the respective return opening; 
     wherein the manifold comprises a chamber divided longitudinally by a transverse wall into the first area on a first side of the wall and the second area on a second side of the wall and wherein the transverse wall terminates at one end at a position spaced from an adjacent end of the chamber to define an undivided portion of the chamber at said end which forms the transfer area. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       One embodiment of the invention will now be described in conjunction with the accompanying drawings in which: 
         FIG. 1  is an isometric view of a manifold of a furnace according to the present invention wherein the heating system which applies heat to liquid in a circuit is shown only schematically. 
         FIG. 2  is an isometric view from the opposite side relative to  FIG. 1  showing the furnace of  FIG. 1  and including two heat transfer loops connected to the manifold which are again shown only schematically. 
         FIG. 3  is an end elevational view of the manifold of  FIG. 1 . 
         FIG. 4  is a cross-sectional view along the lines  4 - 4  of  FIG. 3 . 
         FIG. 5  is a cross-sectional view along the lines  5 - 5  of  FIG. 3 . 
         FIG. 6  is a front elevational view of the manifold of  FIG. 1 . 
         FIG. 7  is a cross-sectional view along the lines  7 - 7  of  FIG. 6 . 
         FIG. 8  is a cross-sectional view along the lines  8 - 8  of  FIG. 6 . 
     
    
    
     In the drawings like characters of reference indicate corresponding parts in the different figures. 
     DETAILED DESCRIPTION 
     In  FIGS. 1 and 2  is shown a furnace  10  arranged for heating a heat transfer liquid filter communicates the liquid to different locations for heating zones to be heated by the furnace. The furnace comprises a manifold  11  which is connected to a furnace heat exchanger  12  within a chamber  13  where the heat exchanger  12  receives heat from a heat source schematically indicated at  14  so as to apply heat to the transfer liquid within the heat exchanger  12 . The furnace heat exchanger has an outlet  15  and a cooled liquid return  16  so that the cooled liquid passes through the furnace heat exchanger  12  to be heated and discharged through the outlet  15 . A furnace pump  17  attached to the manifold  11  has an inlet  18  for receiving the heated liquid and transferring the liquid through the pump after a rate determined by the pump into the manifold  11 . The manifold  11  further includes a return pipe  19  which carries cooled liquid and returns it through a shutoff valve  20  a coupling  21  which feeds the cooled liquid back to the inlet  16 . 
     This arrangement thus provides a circuit around which the liquid is pumped so as to pass through the heat exchanger  12  and to transfer heat from the source  14  into the liquid within the manifold  11 . 
     The liquid is typically water often supplemented by anti-freezing agents and other materials known to persons skilled in the art. However liquids can be used which transfer heat from the source  14  to the areas to be heated. 
     The manifold  11  includes two discharge openings  22  and  23  from which the heated liquid within the manifold can be extracted and transferred through heating loops to two heat exchanges  24  and  25 . Thus the heat exchanges are located on a respectable loop  26 ,  27  each of which includes a respective pump  28 ,  29  for transferring the liquid around the loop from the discharge opening  22 ,  23  back to a return opening  30 A,  30 B at the manifold  11 . The rate of flow of the liquid around the loops is determined by the pumps  28  and  29 . 
     The manifold further includes a bypass duct  31  connected on a downstream side  32  of the pump. At the inlet  18  to the pump is provided a shutoff valve  33  which controls the entry of the heated water into the inlet of the pump. The bypass duct  31  is connected to a boiler protection valve  34 . Valves of this type are well known to persons skilled in the art and include a temperature controlled valve element  35  which allows water to pass from the bypass  31  to the return duct  19 . This flow is closed off as the temperature at the valve  34  increases and instead liquid is drawn from an outlet  36  of the manifold  11 . In this way on startup of the furnace while the liquid is not yet heated to the required temperature, all of the flow bypasses the manifold  11  through the bypass duct  31  allowing the temperature of the heat transfer liquid to be rapidly increased by circulation through the heat exchanger  12 . Only when the temperature in the transfer liquid increases does the valve  34  open to gradually close off flow through the bypass duct  31  while gradually increasing the flow from the outlet duct  36  of the manifold  11 . When operating at full temperature, the bypass duct  31  is fully closed by the valve  34  and all flow passes through the manifold  11 . 
     This boiler protection valve  34  thus protects the boiler by avoiding continual low temperatures within the heat exchanger  12  which could damage the heating system. However the boiler protection valve  34  is the only such valve within the systems of the loops  26  and  27  contained no similar boiler protection valve as this is not required as explained hereinafter. 
     The manifold  11  comprises a chamber  37  which is formed as a square or rectangular duct closed at both ends are  38  and  39 . The duct is divided into two separate areas by a transverse wall  40  so as to form a second area of  41  above the wall  40  and the first area  42  below the wall  40 . As best shown in  FIG. 7  and eight, the wall  40  is a diagonal wall extending from an apex between walls  43  and  44  of the chamber diagonally to an apex between walls  45  and  46  of the chamber. Thus each of the areas  41  and  42  is generally triangular in cross-section and extends partly along the chamber from the end of  38  to a position spaced from the end of  39 . 
     The end of the dividing wall  40  is shown best in  FIG. 4  where to be noted that the end  47  is located in a position spaced from the end  39  of the chamber so as to form a transfer area  48  in the chamber  37  which is defined by the full extent of the chamber  37 . 
     In this way the manifold is divided into the second area  41  defined by the front wall  43 , the top wall  45  and the dividing wall  40 . The manifold also is divided into the first area  42  defined by the bottom wall  44 , the rear wall  46  and the dividing wall  40 . 
     As best shown in  FIG. 7 , the outlet ducts  22  and  23  are connected to the bottom wall  44  buddies into the first area  42 . Also the return openings  30 A and  30 B are connected into the front wall  43  of the manifold that is into the second area  41  above the dividing wall  40 . 
     The manifold  11  is thus divided by the diagonal dividing wall  40  into the first area  42  at which the discharge openings are connected, the second area  41  into which the return openings are connected and the transfer area  48  at the position in the chamber  37  beyond the end  47  of the wall  40 . The discharge openings  22  and  23  are located at spaced positions along the first area spaced from the end  47  of the wall and thus spaced from the transfer area. In the embodiment shown there are two such discharge openings corresponding to two transfer loops for heating two zones. However it will be appreciated that more than two discharge openings can be provided in this first area at spaced positions along the area. Symmetrically the return openings  30 A and  30 B are connected at the front wall  43  again at spaced positions along the length of the second area spaced from the transfer area defined by the end  47  of the transverse wall. Again that there can be more than two such return openings to correspond to the number of discharge openings. The discharge and return openings are longitudinally offset along the manifold, that is the discharge and return openings are staggered each from the next, to provide space for suitable couplings of an arrangement well known to a person skilled in the art. 
     As best shown in  FIG. 4 , the heated water from the pump  17  passes into the outlet  32  which communicates the heated liquid either to the bypass duct  31  or to a transfer duct  50  which communicates the heated water to the manifold  11 . The transfer duct connects to a communication duct  51  which carries the heated water along the rear of the manifold chamber  37  to communicate the heated water into the first area  42  at the rear wall  46  where an opening  53  is provided. Thus the opening  53  for the heated water into the manifold is located in the rear wall  46  communicating with the first area  42  at a position spaced longitudinally of the outlet openings  22  and  23  in a direction toward the end  47  of the dividing wall  40 . Thus the inlet opening  53  is located within the first area  42  at a position spaced from the transfer area  48 . 
     The cooled liquid entering the return duct  19  through the valve  34  passes along an inlet coupling  54  of the valve  34  from the top wall  45  of the chamber  37  out of position within the transfer area  48 . The inlet coupling  54  includes a collar  55  surrounding a discharge opening  56  in the top wall  45  so the collar projects downwardly into the manifold undefined and open mouth  57  of the collar at a position adjacent the transverse wall  40 . However it will be appreciated that in other arrangements the collar may not protrude downwardly as described hereinbefore. 
     In the event that the total volume of liquid drawn from the manifold by the two or more loops is different from the amount of liquid entering and leaving the manifold in the heating circuit, this difference is accommodated by movement of liquid in the manifold between the areas  41  and  42  and through the transfer area  48 . 
     In a situation where the sum of the volumes pumped by the loop pumps  28  and  29  is greater than the volume of liquid entering the manifold from the inlet  53 , this difference is taken up by liquid being pulled into the first area  42  from the second area  41  through the transfer area  48 . This liquid is drawn from the return openings  30 A and  30 B so this extra liquid passes along the second area  41  to the transfer area and then enters the first area  42  to be pulled out of the discharge openings  22  and  23  by the pumps  28  and  29 . 
     As best shown in  FIG. 4 , the position of the inlet  53  is such that the cooled water turning from the second area  41  around the end  47  of the dividing wall  40  passes the inlet  53  before it reaches the discharge openings  23  and  22 . In this way the cooled water which enters the area  42  from the return openings is mixed with the heated water from the inlet  53  before it reaches the discharge openings at  23  and  22 . On reaching the first discharge opening  23  just beyond the inlet  53 , the liquid is mixed to a constant temperature so that the liquid discharging through the opening  23  is at the same temperature as the liquid discharging through the opening  22 . 
     In this way the manifold balances the liquid flow between the two or more loops while ensuring that neither of the loops is starved of heat. This occurs whether the initial installation is arranged so that the total volume of the loops is greater than the total volume of the heating circuit or whether the volume of the heating circuit is temporarily reduced by the operation of the boiler protection valve  34 . 
     The arrangement described herein and therefore provides a simple manifold arrangement which effectively balances and controls the liquid movement while providing a simple construction which can be readily manufactured. 
     The arrangement can be readily and simply installed as the individual loops are of a simple construction without any necessity for control valves. 
     The arrangement provides for a temperature difference between the supply and return of up to 50° on the primary distribution loops to deliver heat load at a much lower rate. The arrangement can ensure adequate flow and water temperature into the heat exchanger. The arrangement can eliminate the need to make manifold using plumbing fittings when setting up the multiple distribution loops for different buildings all zones. In one embodiment the construction provides two supply ports and two return ports. However three or more ports cannot be used. The arrangement herein can enable the use of 1 inch underground pipe for much longer primary distribution lines and still deliver the required heat load. The arrangement herein can allow much smaller more economical pumps to be used on the distribution loops. The simple construction can enable a significant reduction in the plumbing time and therefore the cost of installation. These simple construction of the manifold may enable the installation without professional assistance again reducing the cost. 
     Since various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without department from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.