US3724403A

US3724403A - Forced draft furnace system

Info

Publication number: US3724403A
Application number: US00198345A
Authority: US
Inventors: K Frantzen
Original assignee: Northern Natural Gas Co
Current assignee: Northern Natural Gas Co
Priority date: 1971-11-12
Filing date: 1971-11-12
Publication date: 1973-04-03
Anticipated expiration: 1990-04-03

Abstract

An improved forced-draft heating system wherein the blower can be selectively driven by an alternate power source during electrical power interruptions to remove heated air from the plennum, the system including a water turbine operable from conventional municipal water lines, a coupler for coupling the turbine to the blower and decoupling the blower from the usual electrical motor drive, and manual by-pass means to reconnect the burner to the fuel source during electrical power interruptions.

Description

United States Patent Frantzen Apr. 3, 1973 54] FORCED-DRAFT FURNACE SYSTEM 2,773,488 12/1956 MacCracken et ai ..i22/504 VR Inventor: Karl H. Franzen, Omaha Nebr' 3,405,690 10/1968 Burrus et al. ..i22/504 X [73] Assignee: Northern Natural Gas Company, Primary Examiner-Kenneth W. Sprague Omaha, Nebr. Attorney-Charles J. Merriam et al.

[22] Filed: Nov. 12, 1971 [57] ABSTRACT [21] Appl' 198345 An improved forced-draft heating system wherein the blower can be selectively driven by an alternate power [52] U.S. Cl. ..110/72 R, 122/504 Source during electrical Power interruptions to remove [51] rm. Cl. ..F23c 7/00 heated air from the Plennum, the syswm including a [53] Field of Search 110/72 R 72 122/1 water turbine operable from conventional municipal 1 water lines, a coupler for coupling the turbine to the blower and decoupling the blower from the usual elec- [56] References Cited trical motor drive, and manual by-pass means to reconnect the burner to the fuel source during electri- UNITED STATES PATENTS cal power interruptions.

2,6i9,944 I2/l952 Phillips ..l22/5()4 X 7 Claims, 1 Drawing Figure PATENTEUAPR 3 ms CLOSE) 2 I SAFE TY age-a: VALVE FORCED-DRAFT FURNACE SYSTEM This invention relates to heating systems and in particular to apparatus for providing air circulation in a forced-draft furnace during loss of electrical power.

BACKGROUND OF THE INVENTION The most commonly employed heating system for residential use is of the forced-draft furnace type. In such systems an oil or gas burner develops the heatin aplennum heating chamber and an electrical blower motor forces the heat out of the chamber into the living area through suitable ducts. Standard thermostat controls are employed for regulating burner turn on/off and correlating these operations with the blower.

This system has many significant advantages, however, one distinct disadvantage is the dependence upon electrical power to drive the blower. It is not uncommon for such systems to employ apparatus for shutting off the fuel supply to the burner if electrical power is interrupted, so as to prevent a large build up of heat in the plennum without adequate means to remove and deliver the same. Thus, during severe storms when electrical power is frequently interrupted for long periods until such service can be restored, the heating system is completely down. It therefore becomes of significant importance to provide apparatus and an alternative source of power to the blower to overcome this difficulty.

SUMMARY OF THE INVENTION In accordance with the principles of the present invention, there is provided an improved forced-draft heating system including suitable apparatus and method wherein the blower can be driven by an alternate power source duringrelectrical breakdown so as to deliver heated air as during normal operation. In the illustrated embodiment of the invention here there is provided a hydraulic motor operable from municipal water systems to drive the furnace blower and thereby move heated air from the plennum chamber. Suitable apparatus is provided for engaging the water system with the hydraulic motor during loss of electrical power.

BRIEF DESCRIPTION OF THE DRAWING The FIGURE illustrates an improved forced-draft furnace system embodiment of the present invention utilizing a turbine, and apparatus for selectively engaging the turbine to drive the blower fan during electrical power loss.

DETAILED DESCRIPTION As illustrated in the FIGURE, the improved forceddraft furnace system includes a burner 12 supplied from fuel line 14 for heating the air within plennum chamber 16. It is understood that the plennum chamber 16 has only been shown in schematic view since the construction and arrangement of components therein is well known in the art. A safety valve 18 having a manual override 19 is connected by the burner 12 and the fuel source coupled to input fuel line 20 for selectively controlling the fuel flow to the. burner. The illustration of FIGURE designates a gas heating system, although the principles of the present invention can be applied as well to oil furnaces.

Also mounted immediately adjacent and in communication with the plennum chamber 16 there is provided a blower fan 22 which is driven as in conventional forced-draft furnace systems by electrical motor 24.

In conventional systems, during loss of electrical power, not only is the drive for the blower fan 22 lost, but a normally open (N.C.) safety valve is closed so as to shut off the fuel supply to burner 12. This prevents a build-up of abnormally high temperatures in the plennum chamber, since the normal drive power for the blower has been interrupted.

The improved system shown in FIGURE includes apparatus for reopening the safety valve and for driving the blower fan during periods when the electrical power has been interrupted. In particular, a control relay 26 includes input coil lines 28 coupled to the electrical power source, V. In residential systems the input power source is normally an alternating current, volt supply line. Control relay 26 includes output line 30 connected to safety valve 18 and line 32 connected to normally closed (N.C.) solenoid 34 mounted in water line 36.

When electrical power is interrupted, such as during severe ice or electrical storms, the control relay 26 loses its operating voltage on line 28. Through suitable relay contacts (not shown) of relay 26 a close signal is sent on line 30 to shut off the normally open safety valve 18. Simultaneously, through another set of relay contacts (not shown) of relay 26 a signal is coupled through line 32 to water solenoid valve 34 so as to open the normally closed valve. Manual override or bypass means 19 is provided to manually reopen safety valve 18. In the alternativve, the bypass means can be provided around safety valve 18 (such as an additional fuel line with manual valve).

Opening of water solenoid valve 34 couples water pressure through water line 36 to a hydraulic motor, such as turbine 38. Water turbine 38 is a standard type of turbine element including turbine blades rotatingly driven by the water pressure in line 36 which drivingly engages the turbine blades at their periphery. The rotating turbine blade elements are connected by suitable means to a shaft 40 and through suitable idler coupler means 42 to the blower fan shaft 44. The idler coupler 42 comprises a standard clutch element coupled to motor 24 for rotating blower shaft 44 during normal operation, and for selectively decoupling motor 24 and coupling turbine shaft 40 to the blower 22 when there is electrical power failure. That is, if motor 24 is operating as the drive source, the idler coupler 42 disengages the turbine 38. On the other hand, if turbine 38 is operating as the drive source, the idler coupler disengages the motor. Turbine 38 includes a shroud element 46 for capturing the waste water discharged towards the center within turbine 38. The water within shroud 56 may conveniently be connected to a suitable drain, such as the normal house waste lines.

In the event the water pressure drops below a predetermined limit which is required to operate turbine 38 for turning blower fan 22 and removing the heated air within plennum chamber 16 at a safe rate, there is provided a pressure safety switch 50 suitable mountedwithin water line 36. Pressure switch 50 is connected to a battery 52 and pressure relay 54. In the event of low water pressure, pressure relay 54 is operated to close associated relay contact 56 in line 58 interconnecting battery 52 with safety valve 18. Closing of contact 56 in response to a detection of low water pressure therefore recloses safety valve 18 to disconnect burner 12 from the fuel line.

Therefore, the improved forced-draft furnace system shown in FIGURE can be operated in two modes. In the normal mode of operation safety valve 18 is normally open to couple the fuel line to burner 12 and electrical motor 24 is operated by the power source to drive blower fan 22 through coupler 42 for forcing the heated air in plennum chamber 16 into the delivery duct system. It is understood that the various thermostat controls and other standard temperature actuated controls for responding to the environment and selectively turning on and off burner 12 as well as motor 24 have not been shown herein since they are not a part of the present invention, although they would of course be normally included in an operating system.

In the electrical power failure mode, control relay 26 responds to the loss of electrical power to close the safety valve 18 and to open the normally closed water solenoid valve 34. The manual override or bypass means 19 is then actuated to reconnect burner 12 with fuel line 20 and thereby override the close signal on line 30. The system can now operate in the emergency mode since fuel is being fed to burner 12 and blower fan 22 is being rotatingly driven by water pressure through turbine 38. The operation of pressure switch 50 to shut off safety valve 18 in the event of a drop in water pressure below a predetermined limit has already been set forth.

It is to be understood of course that the turbine 38 need not be of sufficient size to match the horsepower requirements of the blower fan 22. That is, only sufficient power is necessary to rotate the blower to continuously purge the heated air from plennum 16 to avoid overheating. When operating the turbine from ordinary residential water pressure lines of 40-100 psi about one-tenth horsepower will be developed. A typical turbine diameter of 12-14 inches (blade tip to blade tip) with approximately one-half inch blade working surface which is driven under the water pressure is sufficient for use in the present invention. There has thus been provided in accordance with this invention an auxiliary power source for the movement of air in a forced-draft furnace during electrical power failures.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

What is claimed is:

1. In a forced-draft furnace system including a burner having an input connectable to a fuel source for providing heated air, a blower for moving said heated air, an electric motor for driving said blower, the improvement comprising means for selectively driving said blower during interruption of electrical power, including:

a turbine having an input end and an output end, and operable from a fluid pressure source for driving said blower;

means, connected to the input end of said turbine, and selectively operable during interruption of electrical power, for enabling connection of said turbine input end with a fluidpressure source; and drive coupling means intermediate said blower, electric motor and turbine for selectively coupling the output end of said turbine and blower in driving engagement and de-coupling said blower and electric motor during interruption of electrical power so as to move said heated air near said burner.

2. A system as claimed in claim 1, including a fuel valve connected to the input of said burner, means operated by the interruption of said electrical power for closing said fuel valve at the input to said burner thereby shutting off the fuel input thereto, and bypass means for bypassing said valve and enable said burner to be re-connectable to said fuel source during interruption of electrical power.

3. A system as claimed in claim 2, wherein said bypass means comprises a manually operable override portion of said fuel valve.

4. A system as claimed in claim 1 wherein said turbine, comprises an hydraulic turbine connectable to a water pressure source during interruption of electrical power.

5. A system as claimed in claim 4, wherein said means for enabling connection of said turbine input end with a fluid pressure source comprises a normally closed solenoid valve and means for re-opening said solenoid valve when electrical power is interrupted.

6. A system as claimed in claim 5, including a pressure switch mounted adjacent the input end of said turbine for detecting a water pressure less than a predetermined magnitude and providing a corresponding output indication thereof, and actuating means for responding to said output indication for re-closing said fuel valve.

7. In a forced-draft gas furnace system including a burner having an input connectable to a gas source through a safety valve for providing heated air, a blower for moving said heated air, an electric motor for driving said blower, the improvement comprising means for selectively driving said blower during interruption of electrical power, including:

an hydraulic turbine having an input and an output end;

said turbine connectable to a water pressure source for driving said blower;

a normally closed solenoid valve connected to said turbine input, said solenoid valve being re-openable to enable connection of said turbine input end and a water pressure source;

manual bypass means for bypassing said safety valve during interruption of electrical power so as to reconnect said burner with a gas source;

a drive coupler for coupling said blower to said turbine output end and de-coupling said blower and motor during interruption of electrical power; and

pressure actuated switch-means for responding to any water pressure level at the input end of said turbine less than a predetermined magnitude and for closing the burner input.

l I. i

Claims

1. In a forced-draft furnace system including a burner having an input connectable to a fuel source for providing heated air, a blower for moving said heated air, an electric motor for driving said blower, the improvement comprising means for selectively driving said blower during interruption of electrical power, including: a turbine having an input end and an output end, and operable from a fluid pressure source for driving said blower; means, connected to the input end of said turbine, and selectively operable during interruption of electrical power, for enabling connection of said turbine input end with a fluid pressure source; and drive coupling means intermediate said blower, electric motor and turbine for selectively coupling the output end of said turbine and blower in driving engagement and de-coupling said blower and electric motor during interruption of electrical power so as to move said heated air near said burner.

4. A system as claimed in claim 1 wherein said turbine comprises an hydraulic turbine connectable to a water pressure source during interruption of electrical power.

7. In a forced-draft gas furnace system including a burner having an input connectable to a gas source through a safety valve for providing heated air, a blower for moving said heated air, an electric motor for driving said blower, the improvement comprising means for selectively driving said blower during interruption of electrical power, including: an hydraulic turbine having an input and an output end; said turbine connectable to a water pressure source for driving said blower; a normally closed solenoid valve connected to said turbine input, said solenoid valve being re-openable to enable connection of said turbine input end and a water pressure source; manual bypass means for bypassing said safety valve during interruption of electrical power so as to re-connect said burner with a gas source; a drive coupler for coupling said blower to said turbine output end and de-coupling said blower and motor during interruption of electrical power; and pressure actuated switch means for responding to any water pressure level at the input end of said turbine less than a predetermined magnitude and for closing the burner input.