US 3640266 A
A humidifier assembly comprises a housing coupled to the exterior of a furnace plenum chamber and carries a spray nozzle which extends through the plenum wall and into the plenum chamber along with a thermostatic switch responsive to temperature in the plenum chamber. The switch is connected to a solenoid valve controlling delivery of water to the spray nozzle. In turn, the solenoid valve and the plenum thermostatic switch are series connected with a humidistat responding to the humidity in the space served by the furnace. This circuit is connected in parallel with the furnace blower motor which is controlled by another thermostatic switch positioned in the air passage leading to the plenum chamber. The blower control switch closes at a temperature above, and opens at a temperature below, the temperatures which close and open the thermostatic switch of the compact humidifier assembly.
Description (OCR text may contain errors)
United StatesPatent [151 3,640,266 Ernest 5] Feb. 8, 11972  AIR-HUMIDIFYING SYSTEM AND 3,262,444 7/1966 Davidson ..126/113 COMPACT SPRAY HUMIDIFIER FOR THE SAME  Inventor: Dale S. Ernest, Beltsville, Md.
[731 Assignees: Jesse l. Broughton; John G. Hannon, Md.
 Filed: July 1, 1970 [211 App]. No.: 51,585
 U.S.Cl v.126/113  Int. Cl... F24f 3/14  Field oiSearch ..126/113; 236/44, 44A
 References Cited UNITED STATES PATENTS 3,490,436 1/1970 Hart ..126/113 3,289,936 12/1966 C0burn.... ....236/44 2,503,002 4/1950 Shreve ..126/113 2,584,650 2/1952 Woodrulf... ..126/113 3,102,531 9/1963 Gross ..126/113 HOUSEHOLD VOLTAGE Primary Examiner--Charles J. Myhre Attorney-Sughrue, Rothwell, Mion, Zinn & Macpeak ABSTRACT A humidifier assembly comprises a housing coupled to the exterior of a furnace plenum chamber and carries a spray nozzle which extends through the plenum wall and into the plenum chamber along with a thermostatic switch responsive to temperature in the plenum chamber. The switch is connected to a solenoid valve controlling delivery of water to the spray nozzle. in turn, the solenoid valve and the plenum thermostatic switch are series connected with a humidistat responding to the humidity in the space served by the furnace. This circuit is connected in parallel with the furnace blower motor which is controlled by another thermostatic switch positioned in the air passage leading to the plenum chamber. The blower control switch closes at a temperature above, and opens at a temperature below, the temperatures which close and open the thermostatic switch of the compact humidifier assembly.
4 Claims, 2 Drawing Figures INVENTOR I DALE s. ERNEST BY S u L -L Kim-4:040, M
ATTORNEYS BACKGROUND OF THE INVENTION 1. Field of the Invention v This invention relates in general to air humidifiers for forced warm air furnaces, and more particularly to humidifiers which force moisture in the form of a fine spray or mist into the plenum of a furnace or its duct work prior to its distribution into the space served by the furnace.
2. Description of the Prior Art Heretofore, various types of humidifiers which force moisture into forced warm air furnace heating systems have customarily been electrically connected to take their operating power from the blower motor circuit, thereby allowing them to function when the blower is operating. With the power coming from the blower motor circuit, the operation is conventionally controlled by means of an adjustable humidistat which is connected in series with the humidifier", the humidistat measuring the humidity in the space served by the furnace. If the humidity is lower than the setting of the humidistat, an electrical switch is closed which allows the humidifier to operate any time the blower is operating. When the humidity in the space served by the furnace has been brought up to the setting of the humidistat, the humidistat switch opens and the humidifier ceases to operate.
Such prior art types of humidifier force moisture into the heating system during the entire period of blower operation, providing the humidistat switch is closed. Conventionally, the blower-control switch in the furnace closes, at a relatively high temperature, for instance 140 F., which then starts the blower running. The blower continues to run until the temperature in the furnace drops to a relatively low level, on the order of 100 F., when the blower control switch opens. Conventionally, the blower control switch constitutes a temperature sensitive switch positioned within the air space between the combustion chamber and the outside wall of the furnace. The'blower control switch is normally open but set to close at a relatively high temperature, and to reopen at a temperature on the order of 40 F. lower than that tending to initially close the same. While it is necessary to have the blower control switchcut off operation of the blower at temperature substantially below that which originally initiates blower operation, it is possible that such a temperature is insufficient to ensure that all of the moisture being delivered by the humidifier to the plenum will be vaporized and some will settle in the ductwork.
It is desirable, therefore, to limit operation of the humidifier to the time when the temperature is sufficiently high to vaporize all of the liquid delivered by the humidifier. U.S. Pat. No. 3,262,444 to Davidson, utilizes the fuel supply capabilities circuit to actuate contacts of a relay so as to limit the operation of the humidifier to that the time when operation of the heat source of the furnace and operation of the blower are concurrent; the heat source operation being controlled by a thermostat in the space or room served by the furnace. However, there are certain times after the heat source and blower have been turned off when residual heat in the combustion chamber or heat exchanger is sufficient to heat the air to a temperature high enough to restart the blower operation without operation of the heat source. Under such circumstances the humidifier cannot operate, since the heat source is not in operation, although there is sufiicient temperature in the plenum to vaporize any moisture which would be introduced by the humidifier.
SUMMARY OF THE INVENTION The present invention provides a humidifying system for a warm air furnace in which moisture is injected into the heating system only when the blower is operating andthe temperature in the heating system is sufficiently high to ensure complete vaporization of the moisture. Further, the present invention provides a novel and compact humidifier assembly for forced ture, requires minimum maintenance and is easy to install in existing furnaces.
Other objects, advantages and capabiltieis of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawing which illustrates the preferred embodiment of the present invention.
BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an elevational view, partially in section, of a warm air furnace of the upfiow type employing a compact spraytype humidifier assembly in the humidifier system of the present invention connected to the furnace blower circuit as illustratedby the electrical schematic diagram forming a portion of the figure.
FIG. 2, is a sectional view of a portion of the warm air furnace of FIG. 1 illustrating the improved spray-type humidifier assembly of the present invention as employed in conjunction with the system illustrated in FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, wherein like reference characters designate corresponding parts throughout the several figures, FIG. 1 illustrates a conventional furnace 10 of the upflow type, having the usual combustion chamber or heat exchanger 12 heated by conventional means (not shown). The combustion chamber or heat exchanger heat source is conventionally controlled by a roomthermostat (not shown) located in the area served by the furnace and functions to heat the combustion chamber or heat exchanger 12 and consequently the airspace 42 between it and the outer shell of the furnace 10. A blower motor 14 is typically coupled by a belt to a blower 1S whichreceives air through a cold air return duct 16 and forces the same through the airspace 42 between the combustion chamber or heat exchanger and thence into plenum 17, where it is distributed through d uctwork 46 to the area being served. The blower motor 14 is typically connected to the household voltage leads 1] and 19' via lead 18 with the other lead 19 from the blower motor connected directly to a fixed contact 40 of a normally open thermostatic blower control switch 13 which is mounted on the furnace so as to measure the temperature of the air in the space 42 between the combustion chamber or heat exchanger 12 and the outer shell of the furnace. The other and movable contact 41 of the thermostatic blower control switch l3'is connected'directly to tee household voltage lead 19'. In conventional fashion, at a predetermined temperature, for instance, 140 F., the thermostatic blower control switch 13 closes and an electrical circuit is completed from the household voltage leads 11 and 19' to the blower motor 14, energizing the same. Air is forced through the system as indicated by the several arrows.
Since the rate of heat transfer from the combustion chamber or heat exchanger 12 is greater than the rate input from the heat source, the temperature in the airspace 42, and consequently in plenum 17, is constantly dropping. When the temperature in the airspace 42 has fallen to a predetennined level, for instance 100 F., the thermostatic blower control switch 13 opens and the blower motor 14 is turned off. This cycle is repeated until the temperature in the space served by the furnace reaches the setting of the thermostat, whereupon the heat source itself is turned off until such time as the temperature drops sufficiently to cause the thermostat in the space being served to reinitiate the furnace cycle.
The present invention is directed to an improved spray-type humidifier assembly and a novel circuit connection for use in a conventional furnace which provides a unique humidifier system operating to overcome the disadvantages of the prior art systems. As such, reference to FIG. 2 indicates that the humidifier assembly 20 constitutes a single unit involving a fogor mist-producing nozzle 21 of conventional design which projects from the lower portion of the humidifier housing 22,
warm air furnaces which is simple, inexpensiveto manufacbeing connected to the same through a water supply tube 23,
which in turn is fluid connected to a conventional solenoid valve 24 connected to the household water supply by means of pipe 25 carried within the humidifier housing 22 and generally exterior of plenum chamber wall 47. In this respect, the wall 47 is provided with an opening 48 and the humidifier housing 22 terminates in a mounting flange, provided with annular recess 51 receiving solid gasket 52 or an O-ring seal, physically coupling housing 22 and therefore assembly 20 on to the outer wall 47 of the plenum chamber 17 by means of a plurality of screws (not shown).
ln addition to the mist producing nozzle 21 which projects interiorly of the plenum 17, the humidifier assembly carries its own thermostatic switch 26 which extends into the airstream of the plenum, the thermostatic switch constituting a normally open switch which is set to close at a lower temperature than the closing temperature of the thermostatic blower control switch 13 and which is set to open at a higher temperature than the opening temperature of the thermostatic blower control switch 13. In this respect, one lead 27 of a solenoid valve operating coil 28 is connected to one terminal of the thermostatic switch 26. The other terminal of switch 26 is connected via lead 30 to lead 18 which supplies electricity to blower motor 14. The second lead 31' from the solenoid valve coil 28 is connected via lead 31 directly to one contact 45 of a humidistat 32 which measures the humidity in the area being served by the furnace. The other contact 44 of the humidistat 32 is connected via lead 33 to the other lead supplying electricity to the blower motor, in this case lead 19.
It is important to note that the thermostatic switch 26 is so set that its contacts close at a lower temperature than the closing temperature of thermostatic blower control switch 13 for instance 120 F. and open at a higher temperature than that temperature which opens the same blower control switch for instance 110 F. Thus, in operation, the compact humidifier assembly 20 may be readily coupled in an existing furnace with a modified circuit connection to produce a very effective humidification system in which, in response to operation of a room thermostat, energization of the heat source causes an increase of temperature within space 42 surrounding the combustion chamber. As the temperature increases toward 140 F., for instance, the switch contacts 40 and 41 of the thermostatic blower control switch 13 remain open. However, thermostatic switch 26 associated with the humidifier assembly 20 has its contacts closed when the temperature within the plenum 17 reaches a temperature much lower than 140 F., for instance, on the order of 120 F. Assuming that the humidistat contacts 44 and 45 are closed, it is readily apparent that when the temperature now reaches 140 F. within space 42, contacts 40 and 41 of the thermostatic blower switch 13 close, turning on the blower. Simultaneously, the humidifier operates, since the solenoid coil 28 is energized through the series connection with humidistat 32 and humidifier assembly thermostatic switch 26. As mentioned previously, the temperature in the airspace 42 and plenum 17 continues to drop during operation of the blower. While the thermostatic blower switch 13 closes its contacts at approximately 140 F., such switches are typically set to open when the temperature drops to approximately 100 F. However, in this case, the temperature is insufficient in the plenum chamber to fully vaporize the water exiting from the nozzle-type humidifier 21. The present invention advantageously employs the second thermostatic switch 26 of the system carried as a part of the humidifier assembly 20 for insuring cutoff of the humidifier spray nozzle 21 prior to the temperature decreasing to 100 F. Assuming that the thermostatic switch 26 has been set to open the contacts at 1 F., the secondary control provided by the thermostat 26 advantageously ensures that regardless of the demand by the humidistat and the circuit connection created by blower operating switch 13, water is not added to the moving airstream at a time when complete vaporization of the same is not possible.
By this arrangement, the humidifier unit is regulated by the conventional controls already existing relative to the furnace and a humidistat to introduce moisture into the plenum only when the humidity in the air served by the furnace is below a desired level and during the period between blower turn on by thermostatic blower control switch 13 and the opening of the humidifier thermostatic switch 26.
It will be understood that all particulars as to temperatures and physical configuration are by way of example only, and not by way of limitation. The object in stating them is to indicate one particular organization in which proper functioning of all elements will occur. It will be understood by those skilled in the art that changes may be made in light of this disclosure.
What is claimed is:
l. In a humidifier system including means for introducing moisture under pressure in the form of a fine spray or mist into an air passage to humidify the air circulating therethrough;
for use in a heating system including:
a furnace adapted to heat air for supplying a living space, said air passage means extending through said furnace for circulation of air therethrough;
an electrically controlled heat source for heating air in said passage;
a room thermostat responsive to temperature in the living space for controlling said heat source to energize the same during the period that the room thermostat occupies a demand condition;
an electrically driven blower for circulating air through said air passage means to said living space;
a first thermostatic switch responsive to tcmperaturc in a selected zone of said furnace for operating said blower during the period when the temperature in said zone is above a selective level;
the improvement in said humidifier system comprising:
means for controlling said moisture introducing means including a second thermostatic switch responsive to temperature of said air in said air passage means, and set to close at a lower temperature than that closing said first thermostatic switch and set to open at a temperature higher than that opening said first thermostatic switch, whereby moisture is added to the air only during the operation of said blower, and closure of said second thermostatic switch.
2. The humidifier system of claim 1, wherein said means for introducing moisture comprises a spray nozzle fluid coupled to a source of humidifying liquid, and said controlling means further comprises a solenoid-operated fluid valve coupled between the source of liquid and said spray nozzle, with the solenoid coil series connected to said second thermostatic switch, and said first thermostatic switch.
3. In a humidifier system including means for introducing moisture under pressure in the form of a fine spray or mist into an air passage to humidify the air circulating therethrough;
for use in a heating system including:
a furnace adapted to heat air for supply to a living space,
said air passage extending through said furnace for circulation of air through said furnace, said furnace including a plenum chamber;
an electrically controlled heating source for heating air in said air passage;
a room thermostat responsive to temperature in said living space for controlling energization of said heat source;
an electrically driven blower for circulating air through said air passage to said living space;
a first thermostatic switch means responsive to temperature in a selected zone of said furnace for operating said blower during the period when the temperature in said zone is above a selected level;
the improvement in said humidifier system comprising:
means for controlling said means for introducing moisture including a second thermostatic switch responsive to temperature of said air in said air passage, and set to close at a lower temperature than that closing said first thermostatic switch and set to open at a temperature higher than that opening said first thermostatic switch, whereby moisture is added to the air only during the operation of the blower and closure of said second thermostatic switch, wherein said means for introducing moisture and said controlling means therefore constitute a unitary assembly said assembly comprising: a housing; and means for coupling said housing to the wall of said plenum chamber; said moisture introducing means comprising:
a spray nozzle extending into said air passage means through said wall; and a solenoid-operated valve carried by said housing; exterior of said wall and connected to a supply of water; and
said controlling means comprises a thermostatic switch, extending through said wall and positioned in the path of said circulating air; and
means for electrically connecting said second thermostatic switch to said solenoid-operated valve.
4. The humidifier system of claim 3 wherein said second thermostatic switch and said spray nozzle extend outwardly from said housing within said air passage in spaced parallel fashion, and said housing includes a recess within the end face of the same coupled to said air passage wall, an annular sealing ring carried within said recess and means for removably coupling said housing to said wall with said nozzle and said second thermostatic switch projecting through the opening formed within the same.