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

A furnace includes a pump in a circuit through a heat exchanger and a manifold having a plurality of discharge openings in a first area and return openings in a second area connected by a transfer area with each discharge and return feeding a respective heat loop. A bypass in the circuit includes a temperature controlled protection valve connected between the bypass and the manifold. The heated liquid inlet of the manifold is 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. The manifold is defined by a rectangular chamber divided longitudinally and diagonally by a transverse wall which terminates at one end at a position spaced from an adjacent end of the chamber to define an undivided portion of the chamber at the end which forms the transfer area.

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.

DETAILED DESCRIPTION

InFIGS. 1 and 2is shown a furnace10arranged 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 manifold11which is connected to a furnace heat exchanger12within a chamber13where the heat exchanger12receives heat from a heat source schematically indicated at14so as to apply heat to the transfer liquid within the heat exchanger12. The furnace heat exchanger has an outlet15and a cooled liquid return16so that the cooled liquid passes through the furnace heat exchanger12to be heated and discharged through the outlet15. A furnace pump17attached to the manifold11has an inlet18for receiving the heated liquid and transferring the liquid through the pump after a rate determined by the pump into the manifold11. The manifold11further includes a return pipe19which carries cooled liquid and returns it through a shutoff valve20a coupling21which feeds the cooled liquid back to the inlet16.

This arrangement thus provides a circuit around which the liquid is pumped so as to pass through the heat exchanger12and to transfer heat from the source14into the liquid within the manifold11.

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 source14to the areas to be heated.

The manifold11includes two discharge openings22and23from which the heated liquid within the manifold can be extracted and transferred through heating loops to two heat exchanges24and25. Thus the heat exchanges are located on a respectable loop26,27each of which includes a respective pump28,29for transferring the liquid around the loop from the discharge opening22,23back to a return opening30A,30B at the manifold11. The rate of flow of the liquid around the loops is determined by the pumps28and29.

The manifold further includes a bypass duct31connected on a downstream side32of the pump. At the inlet18to the pump is provided a shutoff valve33which controls the entry of the heated water into the inlet of the pump. The bypass duct31is connected to a boiler protection valve34. Valves of this type are well known to persons skilled in the art and include a temperature controlled valve element35which allows water to pass from the bypass31to the return duct19. This flow is closed off as the temperature at the valve34increases and instead liquid is drawn from an outlet36of the manifold11. 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 manifold11through the bypass duct31allowing the temperature of the heat transfer liquid to be rapidly increased by circulation through the heat exchanger12. Only when the temperature in the transfer liquid increases does the valve34open to gradually close off flow through the bypass duct31while gradually increasing the flow from the outlet duct36of the manifold11. When operating at full temperature, the bypass duct31is fully closed by the valve34and all flow passes through the manifold11.

This boiler protection valve34thus protects the boiler by avoiding continual low temperatures within the heat exchanger12which could damage the heating system. However the boiler protection valve34is the only such valve within the systems of the loops26and27contained no similar boiler protection valve as this is not required as explained hereinafter.

The manifold11comprises a chamber37which is formed as a square or rectangular duct closed at both ends are38and39. The duct is divided into two separate areas by a transverse wall40so as to form a second area of41above the wall40and the first area42below the wall40. As best shown inFIG. 7and eight, the wall40is a diagonal wall extending from an apex between walls43and44of the chamber diagonally to an apex between walls45and46of the chamber. Thus each of the areas41and42is generally triangular in cross-section and extends partly along the chamber from the end of38to a position spaced from the end of39.

The end of the dividing wall40is shown best inFIG. 4where to be noted that the end47is located in a position spaced from the end39of the chamber so as to form a transfer area48in the chamber37which is defined by the full extent of the chamber37.

In this way the manifold is divided into the second area41defined by the front wall43, the top wall45and the dividing wall40. The manifold also is divided into the first area42defined by the bottom wall44, the rear wall46and the dividing wall40.

As best shown inFIG. 7, the outlet ducts22and23are connected to the bottom wall44buddies into the first area42. Also the return openings30A and30B are connected into the front wall43of the manifold that is into the second area41above the dividing wall40.

The manifold11is thus divided by the diagonal dividing wall40into the first area42at which the discharge openings are connected, the second area41into which the return openings are connected and the transfer area48at the position in the chamber37beyond the end47of the wall40. The discharge openings22and23are located at spaced positions along the first area spaced from the end47of 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 openings30A and30B are connected at the front wall43again at spaced positions along the length of the second area spaced from the transfer area defined by the end47of 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 inFIG. 4, the heated water from the pump17passes into the outlet32which communicates the heated liquid either to the bypass duct31or to a transfer duct50which communicates the heated water to the manifold11. The transfer duct connects to a communication duct51which carries the heated water along the rear of the manifold chamber37to communicate the heated water into the first area42at the rear wall46where an opening53is provided. Thus the opening53for the heated water into the manifold is located in the rear wall46communicating with the first area42at a position spaced longitudinally of the outlet openings22and23in a direction toward the end47of the dividing wall40. Thus the inlet opening53is located within the first area42at a position spaced from the transfer area48.

The cooled liquid entering the return duct19through the valve34passes along an inlet coupling54of the valve34from the top wall45of the chamber37out of position within the transfer area48. The inlet coupling54includes a collar55surrounding a discharge opening56in the top wall45so the collar projects downwardly into the manifold undefined and open mouth57of the collar at a position adjacent the transverse wall40. 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 areas41and42and through the transfer area48.

In a situation where the sum of the volumes pumped by the loop pumps28and29is greater than the volume of liquid entering the manifold from the inlet53, this difference is taken up by liquid being pulled into the first area42from the second area41through the transfer area48. This liquid is drawn from the return openings30A and30B so this extra liquid passes along the second area41to the transfer area and then enters the first area42to be pulled out of the discharge openings22and23by the pumps28and29.

As best shown inFIG. 4, the position of the inlet53is such that the cooled water turning from the second area41around the end47of the dividing wall40passes the inlet53before it reaches the discharge openings23and22. In this way the cooled water which enters the area42from the return openings is mixed with the heated water from the inlet53before it reaches the discharge openings at23and22. On reaching the first discharge opening23just beyond the inlet53, the liquid is mixed to a constant temperature so that the liquid discharging through the opening23is at the same temperature as the liquid discharging through the opening22.

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 valve34.

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.