US3647136A

US3647136A - Forced-circulation hot water heating system

Info

Publication number: US3647136A
Application number: US62053A
Authority: US
Inventors: Hans Meier
Original assignee: Joh Vaillant GmbH and Co
Current assignee: Vaillant GmbH
Priority date: 1969-09-12
Filing date: 1970-08-07
Publication date: 1972-03-07
Anticipated expiration: 1989-03-07
Also published as: SE362700B; FR2061140A6; NL163014B; ES382260A2; NL163014C; DE1946242B2; GB1264070A; NL7013014A; BE755714R; JPS507292B1; DE1946242A1

Abstract

A hot water feed trunk runs from a gas fired water heater to a priority valve with branches from the priority valve to a radiator and to a heat exchanger respectively. Return branches from the heat exchanger and from the radiator join a return water trunk leading to the water heater and having a circulating pump therein. The priority valve includes a valve closure and a temperature responsive element positioned to be primarily responsive to cold service water (proceeding to the heat exchanger) and secondarily responsive to the temperature of the water from the feed trunk. When the element is comparatively cool, the feed water is sent to the heat exchanger. When the element is relatively hot, the feed water is sent to the radiator. A first switch closed by the flowing of service water is connected in series with a second switch so that when the two are closed the circulating pump will be energized and the valve controlling the gas flow to the burner will be opened. In one embodiment the second switch is controlled by the same element as actuates the valve closure. In another embodiment a second heat responsive element subjected to the same temperature conditions as the first controls the second switch.

Description

States aten [54] FORCED-CIRCULATION HOT WATER HEATHNG SYSTEM [72] Inventor:

[73] Assignee:

[22] Filed:

Hans Meier, Remscheid, Germany Joli. Vaillant KG, Remscheid, Germany Aug. 7, 1970 [21] Appl.No.: 62,053

Primary Examiner-Edward J. Michael Mar. 7, 1972 AttorneyDarbo, Robertson & Vandenburgh [5 7] ABSTRACT A hot water feed trunk runs from a gas fired water heater to a priority valve with branches from the priority valve to a radiator and to a heat exchanger respectively. Return branches from the heat exchanger and from the radiator join a return water trunk leading to the water heater and having a circulating pump therein. The priority valve includes a valve closure and a temperature responsive element positioned to be primarily responsive to cold service water (proceeding to the heat exchanger) .and secondarily responsive to the temperature of the water from the feed trunk. When the element is comparatively cool, the feed water is sent to the heat exchanger. When the element is relatively hot, the feed water is sent to the radiator. A first switch closed by the flowing of service water is connected in series with a second switch so that when the two are closed the circulating pump will be energized and the valve controlling the gas flow to the burner will be opened. In one embodiment the second switch is controlled by the same element as actuates the valve closure. In another embodiment a second heat responsive element subjected to the same temperature conditions as the first controls the second switch.

4 Claims, 2 Drawing Figures PATENTEUMAR 7 m2 SHEEY 1 OF 2 INVENTOR jgzvs MEIER PAIENTEDMAR 7 m2 SHEET 2 OF 2 INVENTOR Hqzvs MEIER BY M 6%? a? FORCED-CIRCULATION HOT WATER HEATING SYSTEM BACKGROUND AND SUMMARY OF THE INVENTION The invention relates to an improvement and completion of a prior system in which a thermostatically controlled priority valve has its heat-sensing element cooled by incoming cold water of the service water'supply. The heat-sensing element of the priority valve is biased by the feed or return water so that at temperatures below the desired operating temperature of the heating circuit the priority valve permits a proportion of the feed water to enter the return line directly through a bypass (traversing the service water heat exchanger) instead of admitting it into heating circuit. When service water is drawn at a time when the hot feed water is flowing to the heating circuit, the heat-sensing element of the priority valve is intensively cooled by inflowing cold water so that a changeover of the priority valve takes place very rapidly and all the feed water flows through the bypass in which the heat exchanger for service water heating is disposed.

In a system of this kind there are certain disadvantages in summer operation when no water circulation in the heating circuit is taking place and the system is used exclusively for heating service water. Upon the completion of a draw of hot service water, the resultant stray heat in the system causes the heat-sensing element of the priority valve to be heated so that said valve undesirably opens the inlet to the heating circuit until the stray heat is dissipated. Hot water circulation in the heating circuit therefore takes place if service water is once again withdrawn during this period, although only for a short time.

It is the object of the invention to avoid the resultant heat loss of such a prior art system. This is achieved in that a thermostatically electric actuated switch is provided which controls the circulating pump and also controls the gas supply to the burner, said switch being controlled by the same temperature effects to which the heat-sensing element of the priority valve is exposed.

To this end the system may be so arranged that the thermostatic switch is controlled by a separate second heat sensing element which is exposed to the same temperature conditions as the heat-sensing element of the priority valve. To obtain reliable interlocking, the operating temperature of the two heatsensing elements is different with the arrangement being such that, in response to a drop in temperature, the valve closes before the thermostatic switch closes. This temperature offset may not become effective in a clearly defined manner if the temperature of the cold water supplied to the system when service water is drawn off is substantially below the operating temperature of the heat sensing elements.

It is a further object of the invention in a system of the kind described hereinbefore to obtain a simplified construction and to ensure that the thermostatic valve closes reliably before the thermostatic switch. This is achieved by employing a common heat-sensing element for the priority valve and the thermostatic switch, which element will delay the closing of the thermostatic switch relative to the closing of the priority valve. The invention may, for example, be performed in that the heat-sensing element acts upon a rod which is guided through the valve closure of the priority valve and sealingly through the housing of the valve and is operatively connected to the thermostatic switch, the rod having an abutment which, after some travel following the opening of the thermostatic switch, contacts the valve closure and moves it in an opening sense. To this end, the thermostatic switch is connected in series with a flow pressure switch, which responds to the flow of service water, so that the circuit of the solenoid valve and circulating pump to be closed by the flow pressure switch is interrupted by the thermostatic switch for as long as the heat sensing elements are insufficiently cooled.

DESCRIPTION OF THE DRAWINGS FIG. 1 diagrammatically illustrates a forced-circulation hot water system embodying the invention and using two heat sensing elements; and

FIG. 2 diagrammatically illustrates a second embodiment in which only one heat sensing element is provided for the priority valve and the thermostatic switch.

DESCRIPTION OF SPECIFIC EMBODIMENTS The following disclosure is offered for public dissemination in return for the grant of a patent. Although it is detailed to ensure adequacy and aid understanding, this is not intended to prejudice that purpose of a patent which is to cover each new inventive concept therein no matter how others may later disguise it by variations in form or additions or further improvements. The claims at the end hereof are intended as the chief aid toward this purpose, as it is these that meet the requirement of pointing out the parts, improvements, or combinations in which the inventive concepts are found.

The numeral 1 refers to the heat exchanger of a oncethrough water heater supplied with heat by a gas burner 2. A heating circuit, containing radiators 5, is connected to the heat exchanger 1 by means of a feed trunk 3 and a return trunk 4. A circulating pump 6 is incorporated into the return 4. The feed 3 is connected to the inlet socket 7 of a priority valve 7. The feed branch 3', extending to the radiators 5, is connected to a discharge socket 7 A connecting socket 8' of the priority valve 7 is provided for the branch feed 8 leading to the heat exchanger 9. The heat exchanger 9 contains a pipe coil 9' in which service water is heated. The return line 4 has branches to both the heat exchanger and the radiator and a trunk in which the pump 6 is located.

Priority valve 7 has two opposed valve seats 10 and 11. Between them is a valve closure 12 urged toward seat 10 by a spring. Valve seat 10, in conjunction with closure 12, controls the flow from trunk 3 to branch 3' and in the same fashion seat 11 controls the flow to branch 8. Valve closure 12 is connected to valve rod 13 also connected to temperature sensitive element 14. Thus, the valve closure is positioned in response to the temperature conditions applied to sensing element 14.

A cold water conduit 15 connects to a source of service water and to a conduit 16 of the priority valve 7. Valve 7 has an outlet socket 16' from conduit 16. Downstream of outlet socket 16' are the conduit 16'', the pipe coil 9' of the service water heater 9 and the tap valve 17 through which the heated service water may be withdrawn. The duct 16 surrounds the heat sensing element 14 of the thermostatic valve 12 so that the element is cooled by the inflowing cold service water. To a lesser extent the element 14 is influenced by the temperature of the water from trunk 3 and flowing about the outside of conduit 16 while on its way to the space between opposed seats l0, 11.

A second heat sensing element 18 controls an electric thermostatic switch 19 and is surrounded by the duct 16. An electric circuit extends from M,,, R to the parallel connection of the circulating pump 6 and a solenoid valve 20 for controlling the gas supply to the burner 2. This electric circuit has a branch 21 incorporating a room thermostat switch 22 and a feed thermostat switch 23. A diaphragm system 24, responding to the flow pressure, is connected to the cold water line 15 and operates an electric switch 25 which is thus flow responsive. The flow responsive switch 25 and the thermostat switch 1? are serially connected in a branch 26 disposed in parallel to the branch 21 of the electric circuit. The gas valve 20 will be open and the pump 6 energized if (a) both of

switches

22 and 23 are closed, or (b) both of

switches

19 and 25 are closed.

Assuming that the system is cold, the closure 12 of the priority valve will be set as illustrated in FIG. 1 so that the flow from trunk 3 proceeds to branch 8 and through the heat exchanger 9.

If the circulating pump 6 is then started and the burner 2 ignited, water, which is initially still cold, will flow from conduit 8 through the heat exchanger 9 and into the return 4. The heating circuit containing the radiators 5 is thus initially short circuited. The water flowing through the bypass 8 and 9 is heated relatively rapidly. As the heating of the water progresses, the heat sensing element 14 moves the valve clo-' sure 12 from its seat 10 so that an increasing part of the water is admitted through the branch 3 into the heating circuit and the radiators 5. When the operating temperature of the hot water forced-circulation heating system is reached, the valve closure 12 contacts the valve seat 11 due to the action of the heat sensing element 14 so that none of the circulating water enters the bypass 8, 9 and all water accordingly must flow through the radiators 5. This function of the priority valve ensures that an adequate operating temperature of the forcedcirculation heating system can be reached as rapidly as possible, at first without dissipating any heat in the radiators 5 and that heat storage in the service water heater 9 also takes place as rapidly as possible.

If the tap valve 17 is opened for the withdrawal of service water when the forced-circulation hot water heating system is in the operative state, that is to say when the opening through the valve seat 11 is closed, it is desirable that all heat generated by the burner 2 be utilized for heating the service water. This is achieved by restoring the bypass 8, 9 of the heating circuit 3', 5 and by at least partially shutting off the heating circuit. To this end, the cold water flowing through the duct 16 from the conduit 15 substantially cools the heated heat sensing element 14 and overrides the influence thereon of the hot water issuing from the feed 3. The effect of the cold water in the duct 16 is so powerful that the heat sensing element 14 causes the valve closure 12 to block the opening through the valve seat it) relatively quickly and retains it in this position although heated water will then issue from the heat exchanger 1 through the priority valve 7, the duct 8 and the service water heater 9. Owing to the predominating effect of the inflowing cold water in the duct 16 on the heat sensing element 14, the service water heating system is provided with priority relative to the heating circuit 3', 5, without the need for any mechanical or electric motor driven changeover action of the valve closure 12. The priority valve 7 also functions as a water circulation regulating device by means of which the circulation in the heating circuit 3', 5 is stopped or weakened so long as the normal operating temperature has not been achieved.

During operation in summer, the solenoid valve and the circulating pump 6 is switched off by the opening of switch 22 of the room thermostat. If service water is then withdrawn from the tap valve 17, the heat responsive element 18 is cooled (if it is not already cool) and closes switch 19 and switch is closed by the flow of water being detected by flow-responsive device 24. The closing of these two switches opens the solenoid valve 20 and turns on the circulating pump 6 for the duration of the draw of service water. On completion of the withdrawal operation, that is to say when no further cold water flows through the duct 15, the heat sensing element 14 will be heated due to the effect of the stray heat so that the closure 12 is raised from the seat 10. If service water is once again withdrawn, a certain quantity of heated feed water would flow past closure 12- through the opening in valve seat 10 into the heating circuit 3', 5 which would result in an undesirable loss of heat. However, the stray heat influences not only the heat sensing element 14, but also, and to the same extent, the heat sensing element 18 so that it opens switch 19. With switch 19 open the closing of switch 25 will not actuate the solenoid valve 20 or the pump 6. These will only be actuated after the flow of service water through conduit 16 removes the stray heat and the heat-sensing elements 14, 18 are sufficiently cooled to move closure 12 onto seat 10 and to close switch 19. Accordingly, reheating of the feed water is delayed in the event of renewed withdrawal of service water while the service water heater is in the hot state. The delay in reheating is hardly noticeable when withdrawing service water owing to the presence of the service water heater (heat exchanger 9) which stores a certain quantity of heat. However, it prevents hot feed water temporarily being discharged into the heating circuit 3', 5 when the system is operated in summer.

The numeral 31 of FIG. 2 refers to the heat exchanger of a once-through water heater which is supplied with heat by a gas burner 32. A heating circuit, containing radiators 35, is connected to the heat exchanger 31 by means of a trunk feed 33 and a trunk return 34. A circulating pump 36 is incorporated into the return 34. The feed 33 is connected with the inlet socket 37' of a priority valve 37. The feed branch 33', extending to the radiators, is connected to an outlet socket 37". A connecting socket 38 of the priority valve 37 is provided for the connection of a feed branch conduit 38, leading to heat exchanger 39. Return branches from the heat exchanger and the radiators lead to the return trunk 34. The heat exchanger 39 contains a pipe coil 39' in which the service water is heated.

A valve seat 40 is provided in the priority changeover device 37 in a position between the connecting

sockets

37 and 37". A second valve seat 41 is disposed opposite to the valve seat 40 and is used (in conjunction with closure 42) to shut off flow to the connecting socket 38 from socket 37. A valve closure 42 is slideably guided on a valve stem 43 and is disposed between the opposed valve seats 40 and 41. The valve stem 43 has an abutment forming a driver 45 which functions to force the valve closure 42 from its seat 40 against the urging of spring 46. The valve stem 43 extends through the valve body with suitable packing (not shown) thereabout to provide a watertight seal through which the stem can move. The exterior end of the stem 43 actuates an electric switch 47. The driver 45 is positioned on the stem 43 at a spaced distance from the valve closure 42 when the electric switch 47 is closed and the element 44 is relatively cool. As the sensing element 44 is heated by water from feed 33, the switch 47 is therefore opened first and thereafter the valve closure 42 is moved from the valve seat 40. A solenoid valve 48 which controls the supplyof gas to the burner 32 and the circulating pump 36 are connected in an electric circuit having a branch 49 which includes the switches 50 of a room thermostat and 51 of a feed thermostat. A flow-sensitive diaphragm system 53 is connected to the cold water duct 52 and actuates a flow sensitive switch 54. The flow switch 54 and the thermostat switch 47 are connected in series in a branch 55 which is in parallel to the branch 49.

If, with the system cold, the circulating pump 36 is started and the burner 32 is ignited, the cold water in the system flows through the branch 38 to the heat exchanger 39 and into the return 34. The heating circuit containing the radiators 35 is thus initially short circuited. The water circulating in the

bypass

38 and 39 is heated relatively rapidly. As this heated water flows through the priority valve 37 it influences heat sensor 44. With progressive heating of the water the heat sensing element 44 moves the valve stem downwardly to initially open the switch 47. This isof no consequence for the operating condition since the supply of current to the valve 48 and the pump 36 is maintained by branch 49 having closed

switches

50 and 51. Further movement of the valve shank 43 causes the driver 45 to force the valve closure 42 from its seat 40 toward seat 41 so that an increasing part of the circulating water is admitted via the branch 33' into the heating circuit and the radiators 35. When the operating temperature of the hot water forced-circulation heating system is reached, the valve closure 42, under the effect of the heat sensing element 44, closes the opening through valve seat 41 so that no further circulating water can pass via the

bypass

38, 39 into the return 34 and instead all water must flow through the radiators 35. This function of the priority valve results in an adequate operating temperature being rapidly established in the radiators 35 without any heat being dissipated and the storing of heat as rapidly as possible in the service water heater.

lf-the tap valve 56 is opened for the withdrawal of service water when the forced-circulation hot water heating system is in the operative state, that is to say when the valve seat 41 is closed, it is desirable that all heat produced by the burner 32 be utilized for heating the service water; that is, it is desirable for the bypass of the heating circuit 33 35 to be reestablished via the conduit 38 and the heat exchanger 39. To this end, the cold water flowing through the conduit 57 from the duct 52 rapidly cools the heated sensing element 44 and overrides the influence thereon of the hot water issuing from the feed 33. The inflow of the cold water in the conduit 57 is sufficiently intense to enable the heat-sensing element 44 to rapidly retract valve stem 43. This results in the valve closure 42 rapidly closing the opening through the valve seat 40 and thereafter the switch 47 being closed. Both are retained in those positions although heated feed water continues to issue from the feed branch 33 and into the priority valve 37 and then into the

bypass

38, 39. Owing to the predominating influence on the heat sensing element 44 of the influx of the cold water in the conduit 57, the service water heater 39 is therefore provided with priority relative to the heating circuit 33 35 without the need for any mechanical or electric motor driven resetting of the valve closure 42. The priority valve 37, however, also performs'the function of a forced-circulation water regulating system by means of which the circulation in the heating circuit 33 35 is either stopped or reduced for as long as the operating temperature has not yet been reached. During operation in the summer, the solenoid valve 48 and the circulating pump 36 are switched off by the switch 50 of the room thermostat being open.

If service water is drawn off from the tap valve 56, the flow switch 54 closes and if the sensing element 44 is not already cool, it is cooled by the flow of service water so that switch 47 is closed. This condition establishes an electric circuit through branch 55 to open solenoid valve 48 and switch on the circulating pump 36 for the duration of the drawing operation. On completion of the withdrawal operation, that is to say when no cold water continues to issue from the valve 56, the heatsensing element 44 will be heated under the effect of stray heat in the priority valve. Thus, element 44 moves stem 43 to initially open switch 47 and subsequently move the valve closure 42 away from the seat 40.

When service water is once again drawn, the switch 47 will prevent starting of the circulating pump 36 until after the thermostat valve 40, 42 is closed to prevent any circulating water from flowing into the heating circuit 33 35. Reheating of the feed water is thus delayed if service water is withdrawn while the service water heater is still in the hot state. The delay of reheating which accompanies the withdrawal of service water is hardly noticeable owing to the amount of heat stored by the service water heater 39. After closure 42 is against seat 40 and switch 47 closes, there will be an electric circuit through branch 55 to open gas valve 48 and energize pump 36.

I claim:

1. In a hot water heating system comprising a water heater with a gas supply valve having an electric operator, a radiator, a heat exchanger having two first connections for heating water and two second connections for service water, a service water conduit connected to the second connections, a feed line from the heater to one of the first connections on the heat exchanger and to the radiator, a return line from the other first connection and the radiator to the heater, a circulation pump in one of said lines, an electric circuit for energizing the valve operator and circulation pump, and a priority valve device with a valve closure for controlling the flow from the water heater to the heat exchanger in response to flow through the service conduit, temperature-responsive means positioned to respond to the temperature of the water in the service conduit upstream of the heat exchanger and to the temperature of the water in the feed line from the heater with the influence of the service water thereon being greater than the influence of the feed water thereon, said temperature-responsive means being operatively connected to said valve closure to operate said priority valve device, and an electric switch in said electric circuit and operatively connected to the temperature-responsive means to be actuated by said temp erature-responsive means;

the improvement wherein said temperature responsive means comprises heat-sensing means, actuating means operatively connecting the sensing means and the closure and the sensing means and the switch for closing the switch with delay only after the closure has moved to a position to block flow from the feed line to the radiator.

2. In a system as set forth in claim 1, wherein said heatsensing means comprises a single heat-sensing element.

3. In a system as set forth in claim 1, wherein said valve device includes a valve body, a valve operating rod extending through the valve body from the interior to the exterior thereof and in the interior extends through said valve closure, means defining a valve seat and a passage from the seat to the radiator, spring means resiliently urging said closure in a given direction toward said valve seat, means forming an abutment on said rod a spaced distance from said closure in said direction, said heat sensing means being connected to said rod to move the rod longitudinally, said switch being positioned at the exterior of said body to be operated by said rod.

4. In a system as set forth in claim 3, including a flowresponsive actuator connected in said service conduit to respond to the flow therein, said actuator including an electric switch which is closed in response to flow in said service conduit, said electric switches being connected in series in said circuit so that when both are closed the circulating pump and the valve operator are energized.

Attesting Officer UNE'EEDSTATES PATENT oFFitE he E3 W CATE 0F (:0 MM??? i ON Patent No. 3 a 136 Dated March 7 19.72;

Inventor(s) Hans Meier It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

111193, "33" should be --33'-- line 18 "33" should be; --33 '---Y line 23, "33" shou ld b'e :33 line 43, "33" should be --33 Column '5, Column 5, Column 5,

Column 5,

Signed and sealed this 18th day of December 1973 (SEAL) At'test:

.RENE D. TEGTMEYER J EDWARD Mo FLETCHER, JR. 7

- Acting Commissioner of Patents

Claims

1. In a hot water heating system comprising a water heater with a gas supply valve having an electric operator, a radiator, a heat exchanger having two first connections for heating water and two second connections for service water, a service water conduit connected to the second connections, a feed line from the heater to one of the first connections on the heat exchanger and to the radiator, a return line from the other first connection and the radiator to the heater, a circulation pump in one of said lines, an electric circuit for energizing the valve operator and circulation pump, and a priority valve device with a valve closure for controlling the flow from the water heater to the heat exchanger in response to flow through the service conduit, temperature-responsive means positioned to respond to the temperature of the water in the service conduit upstream of the heat exchanger and to the temperature of the water in the feed line from the heater with the influence of the service water thereon being greater than the influence of the feed water thereon, said temperature-responsive means being operatively connected to said valve closure to operate said priority valve device, and an electric switch in said electric circuit and operatively connected to the temperature-responsive means to be actuated by said temperature-responsive means; the improvement wherein said temperature responsive means comprises heat-sensing means, actuating means operatively connecting the sensing means and the closure and the sensing means and the switch for closing the switch with delay only after the closure has moved to a position to block flow from the feed line to the radiator.

2. In a system as set forth in claim 1, wherein said heat-sensing means comprises a single heat-sensing element.

4. In a system as set forth in claim 3, including a flow-responsive actuator connected in said service conduit to respond to the flow therein, said actuator including an electric switch which is closed in response to flow in said service conduit, said electric switches being connected in series in said circuit so that when both are closed the circulating pump and the valve operator are energized.