Air flow activated control unit for a furnace

An air flow activated humidifier for use in a ventilation system comprising a water evaporating means, displacing means engageable by the air flow of said ventilation system for displacing said water evaporating means, and activating means operably associated with said displacing means for activating said humidifier when said water evaporating means is displaced. A control system for a flow-through humidifier comprising a pivoting means, returning means, switching means and water valve. A method for humidifying circulated air using an air flow activated humidifier.

FIELD OF INVENTION 
 This invention relates generally to an improved furnace humidifier for use 
 in association with a forced air furnace. This invention further relates 
 to a control system for controlling a furnace humidifier. This invention 
 still further relates to a method for humidifying air heated by a forced 
 air furnace. 
 BACKGROUND OF INVENTION 
 This invention relates to the art of humidifying air circulated by 
 ventilation systems, including heating systems using air heated by a 
 forced air furnace. More particularly, the invention relates to an 
 improved furnace humidifier that is mounted on a forced air furnace, a 
 control system for controlling such furnace humidifier, as well as a 
 method for humidifying air heated by a forced air furnace. 
 Furnace humidifiers of various types are well-known. One type of 
 evaporative humidifier uses a drum or disk component which is partially 
 submerged in a reservoir of water, is rotated while forced air or a 
 convection current of air from a furnace moves through the component. 
 Other furnace humidifiers use a stationary plate or rotating brush to 
 conduct moisture into the path of an air flow. In all of such humidifiers,
 a float valve usually adds water to the reservoir as evaporation occurs, 
 to maintain a constant or predetermined water level in the reservoir. 
 There are numerous disadvantages to the prior art drum or disk type 
 humidifiers. For example, furnace humidifiers of this type are generally 
 complicated and therefore expensive to produce. Not only is a reservoir 
 required, but also a float valve, as well as a motor to sustain the 
 rotation of the drum or disk. 
 Various control systems for use in operation with furnace humidifiers of 
 this first type are also known. For example, U.S. Pat. No. 5,397,510 
 issued on Mar. 14, 1995 to Clark relates to a control system which will 
 reliably signal and/or deactivate upon depletion of the water supply 
 thereto. A further object of this invention is to provide a humidifier 
 with the water container supported by a biasing spring, but with the 
 spring having a non-linear increasing force to ensure operation of the 
 switching system. 
 A second type of evaporative humidifier of relatively more simple 
 construction does not utilize a reservoir but rather employs an 
 evaporation pad through which water is allowed to flow to a drain pipe. 
 The prior art evaporative humidifiers of both the first and second type 
 described above generally require complicated electric means for 
 activating and de-activating the furnace humidifiers so that the furnace 
 humidifier is only active when the forced air furnace is also in 
 operation, to avoid energy waste and extend the lifetime of the furnace 
 humidifier. The need for such complicated electric means increases the 
 complexity and therefore cost of production of such prior art furnace 
 humidifiers. In addition, in the case of many such evaporative 
 humidifiers, the humidifier unit must be connected to the furnace's 
 internal or control wiring, therefore installation of such furnace 
 humidifiers is relatively difficult. 
 There is a need therefore for a furnace humidifier of simple construction 
 that is easy and inexpensive to produce, and which can be installed 
 without difficulty. 
 SUMMARY OF THE INVENTION 
 In accordance with yet another aspect of the invention, an air flow 
 activated humidifier for use in a ventilation system comprising a water 
 evaporating means; displacing means engageable by the air flow of said 
 ventilation system for displacing said water evaporating means; and 
 activating means operably associated with said displacing means for 
 activating said humidifier when said water evaporating means is displaced.
 In accordance with still another aspect of the invention, a humidifier for 
 use in a ventilation system comprising: a casing associated with at least 
 one air duct of said ventilation system; water evaporating means 
 associated with a water source; displacing means for mounting said water 
 evaporating means within said casing whereby air flow of said air duct 
 displaces said water evaporating means from a first resting position to a 
 second displaced position; and activating means operably associated with 
 said displacing means for activating said water evaporating means when 
 said water evaporating means is in said second displaced position. 
 In accordance with a further aspect of the invention, a humidifier for use 
 in association with a forced air furnace having a supply air duct and 
 return air duct, each of said supply air duct and return air duct having a
 duct opening: a casing having a first opening for communicating with one 
 of said supply air duct or return air duct and second opening for 
 communicating with said other one of said supply air duct or return air 
 duct; connecting means for connecting said first opening to said duct 
 opening and said second opening to said duct opening to establish said 
 communication between said casing, supply air duct and return air duct; 
 water evaporating means associated with a water source; means to regulate 
 flow of water from said water source to said water evaporating means; 
 switching means for activating said regulating means; displacing means for
 mounting said water evaporating means within said casing whereby air flow 
 within said air ducts displaces said water evaporating means from a first 
 resting position to a second displaced position; and means for returning 
 said water evaporating means from said second displaced position to said 
 first resting position upon reduction of said air flow in said air ducts; 
 wherein said displacing means and switching means are operably associated 
 to engage said humidifier by activating said regulating means when said 
 forced air furnace generates said air flow. 
 In accordance with a still further aspect of the invention, a control 
 system for a flow-through humidifier associated with the supply and return
 air ducts of a forced air furnace, said flow-through humidifier comprising
 a casing and porous evaporation pad mounted within said casing, said 
 porous evaporation pad being associated with a water source, wherein said 
 casing can be mounted on either of said supply or return air ducts, said 
 control system comprising: a pivoting means for pivoting said porous 
 evaporation ad from a first resting position to a second displaced 
 position upon air flow in said ducts on which said casing is mounted; 
 means for returning said porous evaporation pad from said second displaced
 position to said first resting position when there is no air flow in said 
 ducts; switching means connected to a power source and operably associated
 with said pivoting means when said porous evaporation pad is in said 
 second displaced position; and water valve engageable by said switching 
 means to regulate flow of water from said water source to said porous 
 evaporation pad. 
 In accordance with a still further aspect of the invention, a method for 
 humidifying air circulated by a forced air furnace, said furnace having a 
 supply air duct and return air duct, comprising the steps of: creating 
 openings on said supply air duct and return air duct; mounting on either 
 of said supply air duct or return air duct a casing having a first opening
 for communicating with said supply air duct and second opening for 
 communicating with said return air duct, said casing further including: 
 valve associated with a water source, displacing means, switching means 
 operably associated with said valve and said displacing means for 
 activating said valve and returning means; connecting said first opening 
 to said supply air duct and said second opening to said return air duct to
 establish communication between said casing, supply air duct and return 
 air duct; mounting a flow-through evaporation pad within said casing, said
 displacing means being engageable by air flow present in either of said 
 supply air duct or return air duct on which said casing is mounted to 
 displace said flow-through evaporation pad from a first resting position 
 to a second displaced position; and connecting said casing to a power 
 source whereby said valve is activated when said flow-through evaporation 
 pad is in said second displaced position and said switching means is 
 thereby engaged.

In the drawings, preferred embodiments of the invention are illustrated by 
 way of example. It is expressly understood that the description and the 
 drawings are only for the purpose of illustration and as an aid to 
 understanding and are not intended as a definition of the limits of the 
 invention. 
 BEST MODE FOR CARRYING OUT THE INVENTION 
 In the description which follows, like parts are marked throughout the 
 specification and the drawings with the same respective reference 
 numerals. The drawings are not necessarily to scale and in some instances 
 proportions may have been exaggerated in order to more clearly depict 
 certain features of the invention. 
 Referring to FIG. 1, there is illustrated a preferred embodiment of the 
 furnace humidifier 10 mounted for operation with furnace 12. Furnace 12 
 comprises a supply air duct (warm air) 14 and return air duct (cold) 16. 
 In the mode of operation illustrated herein, a hole such as aperture (not 
 shown) is cut on each of said supply air duct 14 and return air duct 16. 
 Furnace humidifier comprises a casing 20. Said casing 20 further comprises
 a base 22 (shown in FIG. 2), cover 24 and first side opening 26. 
 As best shown in FIG. 2, said base 22 comprises a top wall 28, back wall 
 30, duct aperture 32 disposed within said back wall 30, and bottom wall 
 34. Said base 22 is mounted to either of said supply air duct 14 or return
 air duct 16 by means of fastening means such as screws or the like, 
 whereby duct aperture 32 communicates with either of said supply air duct 
 14 or return air duct 16. First side opening 26 is then connected to the 
 other of said supply air duct 14 or return air duct 16 by means of 
 ordinary air duct tubing, thereby allowing air to flow through casing 20 
 from the high pressure supply air duct 14 to the low pressure return air 
 duct 16. 
 The preferred embodiment of the invention disclosed herein is designed to 
 operate on either a supply air duct or return air duct, whichever may be 
 the most accessible, for example. However, installation on a return air 
 duct is recommended because of the risk of water spillage from the furnace
 humidifier into the furnace body and electric components contained therein
 where casing 20 is installed on a supply air duct. Because the probable 
 consequences of such spillage depend on the design of the specific 
 furnace, some users may decide to install the furnace humidifier disclosed
 herein on a supply air duct, hence the benefit of one furnace humidifier 
 which may be mounted on either of said ducts. The invention herein, 
 however, extends to both modes of installation. 
 Also as seen in FIG. 2, the bottom wall 34 further comprises two parallel 
 lateral protrusions 36, 38, each of which lateral protrusions comprises a 
 first pair of pivoting channels 40 and second pair of pivoting channels 
 42. The preferred embodiment of the invention disclosed herein utilizes a 
 standard flow-through evaporation pad 44 comprised of porous synthetic 
 material commonly used in humidifiers of all types. As shown in FIG. 10, 
 said evaporation pad includes a top opening 46 for communicating with a 
 water pipe and bottom opening 48 for communicating with a drain pipe. In 
 operation, water enters the evaporation pad 44 and flows through and 
 disperses within the porous fibres comprising the evaporation pad 44 and 
 then flow out of bottom spout 48 and casing drain 53 (shown in FIG. 2). 
 As best shown in FIG. 8, the embodiment of the present invention contains a
 water valve 50 which presents means for connecting said water valve 50 to 
 a water source, such as a water pipe connected to an ordinary interior 
 water piping system, in a manner well-known to those skilled in the art. 
 Water valve 50 further communicates with tubing which in turn is received 
 by water inlet aperture 56, as shown in FIG. 2, disposed in top wall 28, 
 said tubing being connected to water spout 59 which provides water to said
 evaporation pad, as best shown in FIG. 7. 
 Said evaporation pad 44 further includes pivoting ridges or legs 54 which 
 are off centre to facilitate pivoting, as best shown in FIGS. 4a, 4b, 5a, 
 5b. Said pivoting ridges 54 may be moulded as part of the frame of said 
 evaporating pad 44, or may be made of plastic or metal, and affixed to 
 said evaporation pad using, for example, an adhesive. Said pivoting ridges
 54 communicate with said pairs of pivoting channels 40, 42. Because said 
 pairs of pivoting channels are marginally larger than pivoting ridges 54, 
 said pivoting ridges 54 do not interlock with said pivoting channels 40, 
 42 but rather pivot in said pivoting channels 40, 42. Bottom spout 48, 
 which is received by casing drain 53 also further assists in minimizing 
 the chance of lateral displacement of the evaporating pad 44. 
 The bottom edge of said pivoting ridges 54 could be straight so as to fit 
 within said pivoting channels 40, 42, or as shown in FIG. 10, the bottom 
 edge 49 of said pivoting ridges 54 could further include a notch 51 so as 
 to straddle said lateral protrusions 36, 38 within said notches 51 thereby
 minimizing the chance of lateral displacement of said evaporation pad 44. 
 In the preferred embodiment shown in FIGS. 4a, 4b, a foam pad 41 could 
 assist in stabilizing the rocking motion of the evaporation pad 44. 
 Alternatively, a stabilizing shoulder 43 can be used as shown in FIG. 5c. 
 The invention described herein also extends to an embodiment where the 
 pivoting channels 40, 42 are presented in the evaporating pad 44 assembly 
 and said pivoting ridges are presented by casing 20. 
 In order to install said evaporation pad 44, as disclosed in the preferred 
 embodiment of the invention described herein, said pivoting ridges 54 are 
 placed in either of said pivoting channels 40, 42 within said casing 20. 
 Said top opening 46 of the evaporation pad is connected by means of tubing
 to water spout 59. Sufficient tubing is used so as not to impede movement 
 of the evaporation pad 44 within casing 20. Further tubing is passed 
 through casing bottom aperture 53 and then to a water drain to drain water
 that has flowed through evaporation pad 44. 
 As best shown in FIG. 8, the invention described herein further includes a 
 switching means 60, which as shown in FIG. 9 is electrically connected to 
 water valve 50. Switching means 60, which is also seen in FIGS. 4a, 4b, 
 5a, 5b is a standard limit switch with a contact arm 61. Switching means 
 60 is further connected to selecting switch 62 (as shown in FIG. 8) which 
 allows selection of whether a circuit is closed when contact arm 61 is 
 depressed or when contact arm 61 is not depressed. 
 Water valve 50 is a standard solenoid valve. The control circuit of the 
 invention described herein, as best shown in FIG. 9, utilizes a 24V 
 current which is supplied by means of electric wiring and a transformer, 
 which transformer is connected to a standard 110V electric plug. 
 Now referring to FIGS. 4a, 4b, 5a, 5b, various cross-sectional views of the
 evaporation pad 44 are shown, as installed within casing 20 by means of 
 either of said pairs of pivoting channels 40, 42 and pivoting ridges 54. 
 Said switching means 60, as discussed above, comprises contact arm 61 
 which communicates with the interior of casing 20 occupied by evaporation 
 pad 44 by means of contact arm aperture 64, as best seen in FIG. 2. 
 As best shown in FIG. 5c, the preferred embodiment of the invention 
 described herein further comprises a stabilizing shoulder 43 adjacent to 
 said pivoting ridges 54. Said pivoting channels, 40, 42, pivoting ridges 
 54 and stabilizing shoulder 43 in cooperation with said evaporation pad 44
 ensure that the evaporation pad 44 is balanced within said casing 20 when 
 in the first resting position. 
 Now referring to FIG. 4a, evaporation pad 44 is shown in operation as 
 mounted to the return air duct of a furnace, in which case said selecting 
 switch 62 is in the "RETURN" position, in which case contact arm 61 closes
 a circuit connection when it is engaged; and said pivoting ridges 54 are 
 placed in said first pair of pivoting channels 40. In FIG. 4a evaporation 
 pad 44 is in the first resting position in which contact arm 62 is not 
 engaged. 
 Now referring to FIG. 4b, evaporation pad 44 is also shown in operation as 
 mounted to the return air duct of a furnace, but now in a second displaced
 position. When the furnace is in operation and air is drawn in for heating
 through the return air duct, the pressure is lower inside the return air 
 duct than outside. Consequently, as shown in FIG. 4b, when the furnace is 
 in operation air flows from the higher pressure supply air duct, through 
 casing 20 so as to force evaporation pad 44 toward duct aperture 32, 
 whereby pivoting ridges 54 pivot within said first pair of pivoting 
 channels 40, whereby said evaporation pad 44 pivots to said second 
 displaced position. Also as shown in FIG. 4b, said evaporation pad 44 
 comes into contact with contact arm 61 thereby engaging said water valve 
 50. Said water valve 50 thereby opens the flow of water to evaporation pad
 44 consequently bringing the furnace humidifier into operation. 
 When the furnace is deactivated, and thereby the flow of air is reduced in 
 said return duct, the pressure within the return duct returns to normal 
 and gravity causes the evaporation pad 44 to pivot to the first resting 
 position, shown in FIG. 4a. Contact with contact arm 61 thereby ceases, 
 thus deactivating water valve 50 and consequently closing the water flow 
 to the evaporation pad 44. The furnace humidifier is thereby shut off. 
 As discussed earlier, the preferred embodiment of the invention presents a 
 second pair of pivoting channels 42 to receive the evaporation pad 44 in 
 the supply air duct mounting, as shown in FIGS. 5a, 5b. The preferred 
 embodiment disclosed herein is easily installed for use by mounting the 
 furnace humidifier on a supply air duct by simply selecting "SUPPLY" using
 selecting switch 62 whereby a circuit is closed by switching means 60 when
 contact arm 61 is not engaged, and placing said pivoting ridges 54 in said
 second pair of pivoting channels 42. Now referring to FIG. 5a, evaporation
 pad 44 is shown in operation as mounted to the supply duct of a furnace, 
 said evaporation pad being in the first resting position. 
 Now referring to FIG. 5b, evaporation pad 44 is also shown in operation as 
 mounted to the supply air duct of a furnace, but now in a second displaced
 position. When the furnace is in operation and air is being forced out 
 through the supply air duct, the pressure is greater inside the supply air
 duct than outside. Consequently, air flows from the supply air duct 
 through casing 20 out of first side opening 26, thereby forcing 
 evaporation pad 44 away from duct aperture 32. Pivoting ridges 54 pivot 
 within said second pair of pivoting channels 42 as a result thereby 
 pivoting said evaporation pad 44 to said second displaced position. Also 
 as shown in FIG. 5b, said evaporation pad 44 disengages said contact arm 
 61 thereby engaging said water valve 50. Said water valve 50 thereby opens
 the flow of water to evaporation pad 44 consequently bringing the furnace 
 humidifier into operation. 
 When the furnace is deactivated, and thereby the flow of air is reduced in 
 said supply air duct, the pressure within the return duct returns to 
 normal and gravity causes the evaporation pad to pivot back to the first 
 resting position, as shown in FIG. 5a. Contact with contact arm 61 thereby
 renews, thus deactivating water valve 50 and consequently closing the 
 water flow to the evaporation pad. The furnace humidifier is thereby shut 
 off. Accordingly, pivoting channels, 40,42, pivoting ridges 54 and contact
 arm 1 provide a pivoting means responsive to air flow so as to pivot the 
 humidifier of the present invention, thereby activating said humidifier. 
 It should be understood that the force required to pivot the evaporation 
 pad 44 from the second displaced position to the first resting position 
 must not be greater than the force which is supplied by the air flow 
 travelling within casing 20. For this reason, the preferred embodiment of 
 the invention disclosed herein provides for an angle of 2 degrees as 
 between said back wall 30 of the casing and the wall of the evaporation 
 pad 44 that is proximal to said back wall 30 in the case of both the 
 return air duct and supply air duct mounting, as shown in FIGS. 4a and 4b,
 however other angles could be used also. Employing the preferred 
 embodiment disclosed herein operation of the furnace humidifier was 
 achieved even in air flows of approximately 50 cubic feet per minute, 
 whereas the standard air flow of a forced air furnace is approximately 
 1300 cubic feet per minute. 
 In addition, it is necessary to provide for some means for preventing the 
 evaporation pad 44 from pivoting beyond the second displaced position. 
 This is particularly so in the supply duct mounting where the contact arm 
 61 does not act as such a stopping means. In the preferred embodiment of 
 the invention provided for herein this stopping means is provided by water
 spout 59 which by means of tubing connected to evaporating pad 44 prevents
 the evaporating pad 44 from pivoting beyond the desired second displaced 
 position, particularly in the supply duct mounting. This stopping means 
 could be further provided, however, by providing the evaporation pad 44 
 with a stabilizing shoulder 43 adjacent to said pivoting ridges 54 or foam
 pad 41. 
 For preferred embodiments of the invention disclosed herein a switching 
 means 60 having an operating force of 13 grams has been selected. 
 While modifications well-known to those skilled in the art to the furnace 
 humidifier disclosed herein may be necessary to achieve the benefits of 
 this invention with respect to evaporation pads of unusual size or weight,
 or furnaces generating unusual application force, it has been found that 
 the using the pivoting channels, pivoting ridges, switching means, 
 standard evaporation pads and standard forced air furnaces as described 
 herein, the furnace humidifier operated consistently. 
 In a second preferred embodiment of the invention disclosed herein, a 
 humidistat is electrically connected to the control system described 
 herein in a manner well-known to those skilled in the art, whereby water 
 valve 50 is only activated if contact arm 61 is engaged and the humidity 
 is below a predetermined level. 
 It may be desirable to furnish the invention described herein with a signal
 light to indicate whether the furnace humidifier is in operation or not. 
 Such a signal light may be easily connected with the control system 
 described herein to signal, for example, that the valve is activated, in a
 manner well-known to those skilled in the art. 
 The casing 20 is easily produced from moulded plastic, but may also be 
 produced out of sheet metal. 
 While a control system for a furnace humidifier has been described wherein 
 the electric components are arranged above the evaporation pad, alternate 
 arrangements can be easily adapted to the invention described herein 
 wherein the control system is disposed below or at the side of the 
 evaporation pad are also possible without departing from the scope of the 
 invention. Furthermore, alternate means for facilitating displacement of 
 the evaporation pad within the casing as a result of air flow may be used 
 to achieve the benefits of the present invention, for example, a 
 swivelling platform holding the evaporation pad or a hinge connecting the 
 casing to the evaporation pad and the like. Furthermore, various other 
 electric components may be used to sense displacement of the evaporation 
 pad within the casing or to activate the valve. In addition, while the 
 preferred embodiment of the invention disclosed herein describes a 
 flow-through humidifier the means disclosed herein for activating and 
 deactivating the humidifier using air flow could be easily adapted for use
 in operation with a drum or disk furnace humidifier using, for example, a 
 displaceable drum or disk axis. Still further, while the preferred 
 embodiment described herein employs a water flow as a water source, the 
 invention described herein could also be adapted for use in operation with
 a water reservoir. 
 It should also be noted that the preferred embodiments described herein 
 utilize a by-pass mounting, i.e. the furnace humidifier is mounted on 
 either of a supply air duct or return air duct, and then the casing is 
 connected to the other air duct to use the resultant air flow from the 
 high pressure supply air duct to the low pressure return duct to pivot the
 evaporation pad. However, alternate means of mounting the furnace 
 humidifier described herein are also possible. For example, the furnace 
 humidifier could be mounted on the supply air duct only by cutting two 
 holes in this air duct and erecting an air barrier between the two, 
 mounting the furnace humidifier on one hole and connecting the casing to 
 the other. 
 The invention described herein can include the humidifier in the original 
 equipment manufactured with the furnace, or can consist of a retrofit kit.
 Various embodiments of the invention have now been described in detail. 
 Since changes in and/or additions to the above-described best mode may be 
 made without departing from the nature, spirit or scope of the invention, 
 the invention is not to be limited to said details.