US3638637A

US3638637A - Spray humidifier

Info

Publication number: US3638637A
Application number: US39445A
Authority: US
Inventors: William H Coffman Jr
Original assignee: LEWBILL IND Inc
Current assignee: LEWBILL IND Inc
Priority date: 1970-05-21
Filing date: 1970-05-21
Publication date: 1972-02-01
Anticipated expiration: 1989-02-01

Abstract

A normally closed solenoid valve connects a source of water under pressure to the spray nozzle of a humidifier. An electric switch is connected with the solenoid for energizing it to open the valve. This switch is actuated between on and off positions by means of a normally inactive timer that includes means for holding the switch in each of its positions a predetermined length of time. The timer is provided with means for connecting it in the fan circuit of a forced warm air furnace so that the timer will operate whenever the fan is running.

Description

United States atom Coffman, Jr. Feb. 1, 1972 SPRAY HUMIDIFIER 3,262,444 7/1966 Davidson 126/1 13 [72] Inventor: William H'Coiiman Jr. Mt Pleasant, Pa. 3,490,436 [/1970 Hart ..l26/l l3 [731 Assignee: Lewhill Industries Inc., Scottdale, Pa. P ima y Em h rl J- Myhre 1 Filed: y 1970 AtmrneyBrown. Murray. Flick & Peckham 21 Appl. No.: 39,445 ABSTRACT A normally closed solenoid valve connects a source of water [52] "126/1 13, 236/44 under pressure to the spray nozzle ofa humidifier. An electric 51 Int. Cl ..F24r 3 14 Switch is cmmmed with the M energizing P [58] Fwd of Search 126/1 236/44 R 44 C the valve. This switch is actuated between on and off positions by means of a normally inactive timer that includes means for I 56] References Cited holding the switch in each of its positions a predetemtined length of time. The timer is provided with means for connect- UN TED STATES PATENTS ing it in the fan circuit of a forced warm air furnace so that the timer will operate whenever the fan is running. 3,289,936 12/1966 Cobum ..236/44 2,584,650 2/ l 952 Woodruff 126/1 13 3 Claims, 5 Drawing Figures l n 37 I SPRAY HUMIDIFIER One type of humidifier for forced warm air furnaces sprays a mist of water into the stream of air that is circulated by a fan, through the furnace and the hot and cold air ducts. The humidifier operates only while the furnace is running, but steadily throughout that period. Spray nozzles commonly used for this purpose are generally rated or sized in gallons of flow per hour of continuous operation at certain standard water pressures. For example, a 0.50 g.p.h. nozzle rated at 40 psi. pressure has an orifice diameter of 0.010 inch and will atomize one-half gallon of water in an hour at 40 p.s.i. At 60 p.s.i., the flow increases to 0.60 gallons for the same period of time, while for lower pressures a correspondingly lower flow rate occurs.

The duct work for most furnaces is usually custom made for each house or building. The size and shape of the main plenum chamber and takeoff outlets, while very adequate for the distribution of dry heated air, can present certain difficultics when a fine water mist is injected into them. Short bends, curves, narrow ducts, variable air velocity and turbulence can play havoc with water mist when delivered in greater amounts than the duct work is capable of accepting during a complete fan cycle or even a segment of the fan cycle. On the other hand, if the humidifier does not deliver enough moisture, the desired humidity will not be obtained.

The temperatures at which the furnace fan is signalled to start and stop vary greatly. Also, the temperature of the heated air itself does not always remain constant and is dependent upon the load that the furnace is called upon to supply. In very coid weather the heating cycle can be almost continuous, while in warmer weather the demand is greatly reduced. These temperatures and operating periods of the heating unit have some effect upon how much water mist can be evaporated and carried off safely. If the mist is not fully evaporated, drops of water will appear on the duct walls and rundown and cause internal damage by rusting. It is well known that city water pressures vary greatly throughout different areas of the United States and may be anywhere from about 40 to I50 p.s.i. pressure. A 100,000 Btu. furnace, for example, could under normal water pressures of 40 to 60 psi. readily accept a nozzle of 0.50 gallon per hour flow. However, if the water pressure exceeds 60 p.s.i. the increased flow rate could be excessive for this size of furnace, so that either a nozzle of lower capacity must be installed or a water pressure regulator must be used to allow the normally specified nozzle to flow at its standard rate.

It will be seen that it is important to use the correct size spray nozzle, but for the reasons just pointed out, there are so many variables that it can be difficult to install a nozzle that will give the desired results under all conditions. Furthermore, it is also generally recognized that the life of a spray nozzle is determined mainly by the quality of the water passing through it. Minerals and sediment will eventually build up around the tip of the orifice making cleaning or replacement necessary.

Nozzle life also is dependent to some extent upon the size of the orifice; the smaller the orifice the more susceptible it is to plugging and, conversely, the larger the orifice the longer the nozzle can be used satisfactorily. It would, therefore, be desirable to use a large orifice, but that cannot be done if the water pressure, ducts and temperature are not just right so that there will not be an excess of water.

It is among the objects of this invention to provide a humidifier which can use a larger nozzle orifice than heretofore without delivering too much water, which can be adjusted for use with different water pressures and other conditions which will operate longer without being serviced, and which will not cause run off of water and the resulting damage.

The preferred embodiment of the invention is illustrated in the accompanying drawings, in which FIG. 1 is a front view of the humidifier with part of its front wall broken away;

FIG. 2 is a plan view with part of the top wall broken away;

FIG. 3 is a vertical cross section taken on the line III-III of FIG. I but with the wiring omitted for clearness;

FIG. 4 is a rear view of the humidifier with its rear wall removed; and

FIG. 5 is a circuit diagram.

Referring to the drawings, a rectangular case I is provided in its front wall with a circular opening 2, from which an upwardly inclined spray nozzle 3 projects. The nozzle includes a circular portion that is held in the opening by screws 4 extending from the front wall rearwardly through an integral flange 5 that extends around the nozzle and engages the inner surface of the wall. The tip of the nozzle is provided with a small orifice 7 and supports an encircling drip cup 8 connected at its bottom with an inclined drain tube 9 that extends back through the front wall and noule flange and out of the bottom of the case. Inside the case the nozzle is provided with an integral valve housing 11 for a normally closed valve that is opened when a solenoid 12 supported by the housing is energized. The inlet of the valve is provided with a connection 13 that permits it to be connected to a suitable source of water under pressure. The case is intended to be attached to the outside of a forced warm air furnace plenum I4 or duct by means of four short metal screws extending through holes in the front wall of the case, with the nozzle extending through a small opening into the plenum or duct.

Beside the solenoid valve there is a bracket I5 that is fastened to the top and bottom walls of the case and spaced from its front and rear walls. A wire 16 entering the top of the case is connected to one terminal of the solenoid. Another wire 17 entering the case is connected with movable contact means of a control switch 18 supported from bracket IS in the space between it and the front wall of the case. Actuation of the movable contact may be by means of a button 19 that has two positions. In the normal position, a fixed contact is engaged by the movable contact means and a second fixed contact is spaced from the movable contact. In the other position, this relationship of contacts is reversed. After the force that moves the button away from its normal position is removed, the button returns to its normal position. Such a switch may take various forms. An example is shown in FIG. 5, where a curved leaf spring 21 forms the movable contact means which, when pushed down by the button 19 at its center, will spring upwardly at its ends to leave the first fixed contact 22 and to engage the second fixed contact 23. When the button is released, the spring snaps back to its first or normal position and again engages contact 22 but is separated from the other fixed contact.

Wires

25 and 26 from the two fixed contacts of this switch are connected to two fixed contacts in a manually operable switch 27, such as a slide switch that is provided with a movable bridging contact 28 that can be shifted to connect either fixed contact 29 or fixed contact 30 with a third fixed contact 31. The latter is connected by a wire 32 to the other terminal ofthe solenoid to complete the circuit through it.

In order to actuate the control switch 18, timing means is provided. This likewise can take different forms. It may, for example, be operated by a spring, by an impeller that is turned by the air flowing through the furnace, or by electricity. The timer illustrated includes a synchronous timer motor 33 mounted on the back of bracket 15 and provided with a rotatable shaft 34 extending forward through the bracket and carrying a cam 35 on its front end. The cam is shaped and positioned to periodically depress the button of the control switch as the cam rotates. The timer motor is connected by wires 36 with the

solenoid circuit wires

16 and 17 that extend out of the case, and the latter two wires are connected in the fan circuit of the furnace. Such a circuit includes a heat sensitive switch 37 that normally is open. When the furnace reaches a predetermined temperature, the switch closes and starts the fan 38, which continues to operate until the furnace temperature drops to a predetermined level.

When the fan switch 37 closes electric current flows into the humidifier and starts the timer operating. It continues to operate as long as the fan is on. As the cam is rotated, the control switch button is periodically depressed and released, which alternately closes and opens the solenoid valve circuit. Every time this circuit is closed, water mist is sprayed from the nozzle. The total time that spraying will occur during any period that the fan is operating will depend upon the shape of the cam and the speed of the timer motor. If the cam depresses the control switch button for just 180 of cam rotation, the spray will be turned on half the time and turned off half the time. This will allow a larger orifice to be used than if the spray were constant. Also, by breaking down the humidifier working periods to regular intermittent cycles in this manner, the nonoperating periods of the spray during the fan cycle provide a drying-out period in the humidifying process. Thus, where a steady spray of minutes or more, for example, might result in more spray than the furnace can handle, short injection cycles followed by dry cycles will reduce the requirement that the air temperatures must be very high to evaporate all of the moisture that is introduced. This feature makes it possible to use this humidifier in the cold air return of the furnace where temperatures are much lower than at the warm air side of the furnace.

A further feature of this invention is that the slide switch 2'? permits the relative lengths of the on and off periods of the spray to be changed. If, for example, the cam is shaped to cause spraying for 2 minutes followed by no spray for 1 minute before repeating the cycle, this sequence can be reversed by reversing the slide switch. The other side of the control switch then will be put in the solenoid circuit and the spray will be on for only 1 minute and off for 2 minutes. This arrangement gives considerable flexibility in the operation of the humidifier and enables it to take care of most situations. The spraying intervals occur only while the fan is operating. When the fan stops, the solenoid valve circuit is opened and no spraying can take place.

It will be seen that with one setting of the slide switch the flow is reduced 333/; percent from steady flow, while with the other setting the reduced flow is cut in half; it is only one-third of full flow. The cam and the slide switch give considerable latitude in selecting a nozzle of the largest flow size for a given water pressure for maximum durability without producing the increased flow that would result if the spray were not interrupted while the fan is operating.

lfa humidistat is used for precise regulation ofhurnidity, the humidifier will be shut off temporarily in case the humidity starts to exceed the humidistat setting, even though the fan continues to run. The humidistat switch would be connected in line 16 or line 17 and, of course, normally would be closed.

According to the provisions of the patent statutes, 1 have explained the principle of my invention and have illustrated and described what i now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

lclaim:

l. A humidifier suitable for use with a forced warm air furnace, comprising a spray nozzle, a normally closed solenoid valve connected with the nozzle, means for connecting the valve with a source of water under pressure, an electric circuit for connecting the solenoid of said valve with the intermittently operating circuit of an air circulating fan, an electric control switch in said solenoid circuit provided with a pair of fixed contacts and with movable contact means engageable with either of the fixed contacts and normally engaging one of them, a manually operable switch in said circuit for electri cally connecting either of said fixed contacts with said valve solenoid, and a timer for actuating said control switch and including means for holding said movable contact means in engagement with one of said fixed contacts longer than with the other.

2. A humidifier according to claim 1, in which said timer means is a rotating cam shaped to hold said movable contact means in engagement with one of said fixed contacts substantially twice as long as with the other fixed contact.

3. A humidifier according to claim 1, in which said timer means is a rotating cam, and said control switch includes means engaged by the rotating cam for periodically moving said movable contact means out of engagement with said one fixed contact and into engagement with the other fixed contact.

Claims

1. A humidifier suitable for use with a forced warm air furnace, comprising a spray nozzle, a normally closed solenoid valve connected with the nozzle, means for connecting the valve with a source of water under pressure, an electric circuit for connecting the solenoid of said valve with the intermittently operating circuit of an air circulating fan, an electric control switch in said solenoid circuit provided with a pair of fixed contacts and with movable contact means engageable with either of the fixed contacts and normally engaging one of them, a manually operable switch in said circuit for electrically connecting either of said fixed contacts with said valve solenoid, and a timer for actuating said control switch and including means for holding said movable contact means in engagement with one of said fixed contacts longer than with the other.