Title:
Modular self contained unit ventilator
Kind Code:
A1


Abstract:
A unit ventilator is described in which air treating apparatus is housed within a chassis which is readily removable from a fixedly installed cabinet. The air treating apparatus includes an evaporator, a compressor, a condenser and an air flow system for separately handling air for ventilating and air for condenser cooling and in which the system for condenser cooling provides for evaporative cooling of the refrigerant. The invention contemplates modular system arrangements in which the use of plural chassis in an installation enables the production of a wide range of ventilating capacity from minimal change in alternative chassis modules.



Inventors:
Harshberger, Martin J. (Germantown, TN, US)
Hicks, Steven G. (Cordova, TN, US)
Welch, Timothy D. (Grand Junction, TN, US)
Application Number:
10/298957
Publication Date:
05/20/2004
Filing Date:
11/19/2002
Assignee:
PEF Industries, Inc. (Somerville, TN)
Primary Class:
Other Classes:
165/58, 165/137, 62/262
International Classes:
F24F1/02; F24F13/20; F24F13/22; (IPC1-7): F25B29/00; F25D23/12; F28F7/00
View Patent Images:
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Primary Examiner:
FORD, JOHN K
Attorney, Agent or Firm:
KRATZ, QUINTOS & HANSON, LLP (WASHINGTON, DC, US)
Claims:
1. A modulator unit ventilator, comprising: a cabinet having substantially rectangularly disposed panels forming a fixed enclosure, one of said cabinet panels being detachable to provide access to the interior of said cabinet; at least one slide-in chassis having substantially rectangularly disposed walls and being sized to be readily inserted and removed with respect to the interior of said cabinet; one of said chassis walls being detachable to permit access to the interior thereof; a partition dividing said chassis into an evaporator section and a condenser section containing an evaporator coil and a condenser coil, respectively; a ventilated air discharge opening from said evaporator section and condenser air discharge opening from said condenser section; air handling means including a first blower disposed on one side of said partition for passing input air to said evaporator section and thence to discharge into said space to be ventilated, and a second blower disposed on the other side of said partition for circulating condenser air with respect to said condenser; and inlet means for supplying input air to said first and second blowers, respectively.

2. A modulator unit ventilator, according to claim 1, in which said input air inlet means includes mutually spaced openings in both said cabinet and said chassis defining opening means for receiving outside air and for distributing said outside air to said evaporator and condenser sections of said chassis.

3. A modulator unit ventilator, according to claim 2, in which said input air inlet means includes openings in said cabinet and chassis for supplying return air to said evaporator section of said chassis.

4. A modulator unit ventilator, according to claim 3, including a roll damper mounted for pivotal movement in said evaporator section of said chassis and being operative to proportion amounts of outside air and return air to said evaporator section.

5. A modulator unit ventilator, according to claim 2, including a partition plate disposed in said condenser section of said chassis for dividing intake air flow into a first portion passing to said condenser section and a second portion passing to said evaporator section.

6. A modulator unit ventilator, according to claim 5, in which said partition plate is formed as a condensate collector positioned adjacent said second blower, said blower being thereby operative to circulate a moisture-laden air flow in heat transfer relation with respect to said condenser.

7. A modulator unit ventilator, according to claim 6, including a condensate collection trough arranged to collect condensate generated by said evaporator; and a conductor extending from said collection trough to supply condensate to said condensate collector.

8. The modulator unit ventilator according to claim 4 in which an opening in said partition is oppositely spaced from said opening for supplying return air to said evaporator section, said roll damper being mounted for pivotal movement between said partition, and means for adjusting the position of said roll damper opening and said return air opening for selectively supplying outside air and return to said evaporator section.

9. The modulator unit ventilator, according to claim 8, wherein said partition opening and said return air opening are mutually oppositely spaced with respect to each other; filter plates disposed adjacent each of said openings; and said roll damper having seal members cooperable with each of said filter plates for adjustably determining the composition of air flow into said evaporator sections.

10. The modulator unit ventilator, according to claim 9, including a partition defining a filter door upstanding from a bottom of said chassis, said filter door being cooperable with said roll damper for directing the flow of input air through said evaporator section.

11. The modulator unit ventilator, according to claim 10, wherein said filter door is mounted for pivotal movement with respect to said chassis whereby said filter door is movable to permit access to said filter plates when said one chassis wall is detached.

12. The modular unit ventilator, according to claim 1, including trough means operative to receive condensate generated on a surface of tubes forming said evaporator coil and to deliver said condensate to said second blower to be passed in mixed relation to input air in heat transfer relation with respect to said condensate coil.

13. The modular unit ventilator, according to claim 12, in which said trough means includes a first trough positioned to receive condensate generated on surfaces of said evaporator coil tubes, a second trough positioned in proximity to said second blower, means for transferring condensate from said first trough to said second trough for delivery with input air in heat transfer relation to second condenser coil.

14. A modular unit ventilator, according to claim 1, including independently operable air heating means disposed immediately upstream from said air discharge opening from said evaporator section.

15. A modular unit ventilator, according to claim 14, in which said air heating means comprises electrically operated heating elements.

16. A modular unit ventilator according to claim 14 in which said air heating means comprises a hydronic coil.

17. A modular unit ventilator, according to claim 1, in which said cabinet contains a plurality of slide-in chassis disposed in side-by-side relation, said chassis being each independently arranged for selective insertion and removal thereof with respect to the interior of said cabinet.

18. A method of constructing a modular unit ventilator containing a cabinet having substantially rectangularly disposed panels forming a fixed enclosure, one of said cabinet panels being detachable to provide access to the interior of said cabinet and a plurality of slide-in chassis being sized to be readily inserted and removed from said cabinet, and said chassis having one wall detachable to permit access to the interior thereof, an evaporator coil, a condenser coil and air handling means for passing input air to said evaporator coil and said condenser coil, respectively, and return air to said evaporator coil, said method comprising the steps of: providing each of said chassis with corresponding organization of operating elements; and determining the number and design capacity of said chassis for a cabinet to provide an accumulated design capacity for the cabinet.

19. The method of constructing a modular unit ventilator, according to claim 18, including the step of providing at least two of said chassis of different design capacities.

Description:
[0001] The present invention relates to unit ventilators containing equipment for discharging either cooled or heated air into a space to be ventilated. More particularly, the invention concerns a unit ventilator apparatus in which the principle operating parts of the apparatus are characterized by component modularization whereby, due to apparatus design, the operating parts are all collectively housed in a chassis which is readily installed or removed from the ventilator cabinet. Consequently, replacement or repair of apparatus components can be effected with a minimum of system downtime. Moreover, the invention contemplates installation of a plurality of chassis, each containing the same or substantially the same apparatus whereby, in addition to facilitating apparatus design by the use of modules, in the event of malfunction or other need for removal of a chassis from operation, space ventilation can continue on a partial capacity basis.

BACKGROUND OF THE INVENTION

[0002] Unit ventilators are commonly used for the ventilation of school classrooms or other confined spaces characterized by high density occupancy. Although the principle function of equipment of the concerned type is to provide ventilation cooling by selectively blowing cool outside air into the concerned space, it is frequently found to be desirable to process the air either by mechanically conditioning the air by cooling or by heating it before discharging it from the ventilator. Moreover, it is oftentimes desired that the air be totally or proportionately recirculated, either as fresh incoming air or as air that has been heated or cooled, in order that a high incidence of fresh air ventilation is achieved.

[0003] Consequently, such unit ventilators have usually included a cabinet enclosure in which the component ventilator parts are housed, the ventilator parts including such air conditioning components as evaporator and condenser coils, appropriate blowers for circulating fresh outside air and/or recirculated air in regulated amounts between the respective coils and a compressor for processing the refrigerating fluid. Heating units of an electrically-or fluid-operated variety may also be provided where it is desired to provide the ventilating system with a heating as well as a cooling capability.

[0004] Air conditioning systems of the prior art, particularly those having an alternate heating capability, have been characterized by complex equipment configurations having high initial costs and being expensive to maintain, the expense of which is compounded when it is considered that malfunctions of one or more sections or components of the unit may require extensive periods of inoperativeness while the defective system components are repaired or replaced. Commonly with ventilating units of such prior design, the occasion of equipment failure or malfunction necessitates either termination of occupancy of the affected ventilated space or, alternatively, the use of less effective ventilating apparatus at an increased cost during periods of equipment unavailability.

[0005] It is to the amelioration of the foregoing problems to which the present invention is directed.

SUMMARY OF THE INVENTION

[0006] Accordingly, it is a principle object of the invention to provide a unit ventilator having an air conditioning capability and, if desired, an alternatively operable heating capability.

[0007] It is another object of the invention to provide a unit ventilator of modular design in which the operating components of the system are housed within a chassis enclosure which enables rapid removal and installation of such components during instances of a need for equipment maintenance, repair or replacement.

[0008] A still further object of the invention is to provide a unit ventilator organization in which the design of ventilators of elevated capacities can be accomplished merely by use of selected multiple modules of predetermined design capacities.

[0009] It is a further object of the invention to provide a unit ventilator of modular configuration whereby the engineering and design of ventilators having increased capacity is facilitated by the selective use of plural chassis modules.

[0010] Yet another objective of the invention is to provide a unit ventilator employing plural chassis modules whereby removal of a chassis for service does not prevent reduced capacity operation of the ventilator through the use of the components remaining in the chassis.

[0011] These and other objects and advantages are provided by the hereinafter described modular unit ventilator system which includes a cabinet having substantially rectangularly disposed panels forming a fixed enclosure, one of said cabinet panels being detachable to provide access to the interior of said cabinet; at least one slide-in chassis having substantially rectangularly disposed walls and being sized to be readily inserted and removed with respect to the interior of said cabinet; one of said chassis walls being detachable to permit access to the interior thereof; a partition dividing said chassis into an evaporator section and a condenser section containing an evaporator coil and a condenser coil, respectively; a ventilated air discharge opening from said evaporator section and condenser air discharge opening from said condenser section; air handling means including a first blower disposed on one side of said partition for passing input air to said evaporator section and thence to discharge into said space to be ventilated, and a second blower disposed on the other side of said partition for circulating condenser air with respect to said condenser; and inlet means for supplying input air to said first and second blowers, respectively.

[0012] The described unit ventilator incorporates a selectively adjustable damper for circulating input air consisting of regulated amounts of either or both outside air and/or room return air through the evaporator. Moreover, equipment organization is such that moisture represented by condensate collected from air flowing in heat exchange relation with respect to the evaporator coil is mixed with cooling air for effecting more efficient heat transfer via evaporative cooling of the operating refrigerant in the condenser coil.

[0013] The invention further involves a more flexible unit ventilator design wherein, depending upon desired design capacity, a plurality of independently operated modules of corresponding organization can be utilized in a ventilator cabinet of accommodating size. As a result, not only is continued operation of an installation permitted, albeit at a reduced capacity, in instances of removal from service of a chassis module, but an enhancement of equipment design and engineering is achieved from the use of modules of corresponding design which may be of the same or disparate design capacities.

[0014] For a better understanding of the invention, its operating advantages and the specific objects obtained by its use, reference should be made to the accompanying drawings and description which relate to preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 is a general exploded perspective view of a modular unit ventilator according to an embodiment of the present invention;

[0016] FIG. 2 is a more detailed exploded view of the embodiment of FIG. 1;

[0017] FIG. 3 is a somewhat schematic elevational section view of the embodiment of FIG. 1;

[0018] FIG. 4 is a somewhat schematic front perspective view of the chassis portion of the invention embodiment shown in FIG. 1;

[0019] FIG. 5 is a somewhat schematic rear perspective view of the chassis portion of the invention embodiment shown in FIG. 1; and

[0020] FIG. 6 is a view, similar to FIG. 2, showing another embodiment of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0021] With particular reference to the drawings wherein like reference numerals designate like parts throughout the respective views, there is shown in FIG. 1 an exploded general representation of a modular unit ventilator 10 constructed according to the present invention. The illustrated unit ventilator 10 includes a cabinet 12, and a chassis 14 wherein all of the principle operating parts of the unit ventilator of the invention are contained. The cabinet 12 has a readily detachable front panel 16 that, when removed from the cabinet frame, exposes the chassis 14 for ready removal from the cabinet upon disconnection of the plug 18 which connects the chassis to a source of electric power and control box 54. Handles 17 may be provided on the chassis front panel 16 to assist in moving the chassis with respect to the cabinet.

[0022] As best shown in FIG. 2, the cabinet 12 comprises a frame structure, indicated generally as 20, that includes laterally elongated front and rear struts 22 forming a base 24. Members comprising end ties 26 extend between and connect together opposite ends of the respective struts 22. A plurality of chassis-support rails 28 extend between and connect the respective struts 22 at intermediate locations along the length of the cabinet 12. A pair of end panels 30 close the opposite ends of the frame structure 20, and a pair of side plates 32 extend between the base 24 and an elevated roof support 34 at locations spaced inwardly from the end panels. The roof support 34 contains an elongated opening 36 and is covered by a roof panel 38 having an opening 40 containing a grille 42 which align with the opening 36 from which processed air is discharged from the ventilator.

[0023] The rear of the cabinet 12 is essentially open and is adapted to be fixedly disposed with respect to the outside wall 44 of a building, or the like, shown in FIG. 3 as being provided with a pair of vertically spaced openings 46 and 48 which may be separated by an intermediate wall portion 50. A grill 52 depends from the lower edge of the cabinet front panel 16 and is adapted to pass return air from the ventilated space to the chassis 14 for reprocessing, as hereinafter more fully described.

[0024] Preferably, the cabinet side plates 32 are laterally spaced inwardly from the end panels 30 in order to provide storage areas 33 at opposite ends of the cabinet 12 for accommodating equipment, as for example, the control box 54.

[0025] The chassis 14 comprises an enclosure structure formed of generally rectangularly disposed walls including a base 56, a front wall 58, a rear wall 60, side walls 62 and a sectioned roof 64. A downwardly inclined grate 66 extends substantially parallel to, and communicates with, the grill 52 on the cabinet front panel 16 to permit passage of return air to the ventilator apparatus, as hereinafter described. An opening 67 is provided in the cabinet roof 64 and communicates with the opening 36 in the cabinet roof support 34 to define a processed air outlet from the unit ventilator 10.

[0026] The interior of the chassis 14 contains the elements of a ventilating system for processing air admitted to the apparatus. For this purpose, as best shown in FIGS. 3 to 5, the chassis interior is divided into an evaporator section 68 and a condenser section 70, which sections are separated by a partition plate 72 that stands uprightly from the chassis base 56.

[0027] The evaporator section 68 is divided vertically by a horizontally disposed support plate 74 for a motor board assembly 76 which includes a laterally spaced pair of cylindrical blowers 78 for circulating air to be processed through openings 79 in the motor board support plate 74, which openings define blower discharge outlets to that region of the evaporator section 68 containing the evaporator coil 86 through which the air to be processed passes prior to discharge from the roof openings 36 and 67 in the cabinet 12 and chassis 14, respectively. As shown, the motor board support plate 74 is an elongated member which extends from end-to-end of the evaporator section 68 and suspends from the underside thereof by means of bolts 80, an electric drive motor 82 having oppositely extending drive shafts (not shown) for connection with longitudinally spaced blowers 78, between which the drive motor is positioned. In the disclosed embodiment of the invention, the motor board assembly 76,is shown as comprising two blowers 78 between which a single drive motor 82 is positioned. It should be appreciated, however, that the number of drive motors and the number of blowers to be employed can be increased or decreased based upon the design capacities of the blowers and drive motors selected.

[0028] The upper region of the evaporator section 68 contains the evaporator coil 86, which is elongated laterally, and is defined by a plurality of parallel refrigerant-conducting tubes 88 that extend between headers 90. A condensate collection tray 92 is positioned along the lower end of the evaporator coil 86 and is adapted to receive liquid droplets resulting from the condensation of moisture extracted from the air processed by the evaporator.

[0029] The upper region of the evaporator section 68 may, as shown in FIG. 3, optionally contain heating elements which may be electrically operated heating units 95 and/or a hydronic heater 93 for processing air in the ventilator by heating, instead of cooling.

[0030] The condenser section 70 of the ventilator is disposed on the rear side of the partition plate 72 and contains a condenser heat exchange unit, indicated generally by reference numeral 94. The condenser heat exchange unit 94 comprises a condenser coil 96 having a plurality of tubes, preferably U-tubes, for conducting refrigerant received from the evaporator coil 86. A compressor 98 is interposed in the system and operates to pressurize the refrigerant being returned to the evaporator coil 86. As shown best in FIGS. 3 and 4 of the drawings, the condenser coil 96 is housed within a condenser hood 100, the bottom of which constitutes a motor board assembly 102 that includes a motor board in the form of an elongated plate 104 that underlies and forms the bottom of the condenser hood 100. The motor board plate 102 is desirably inclinedly disposed and mounts a blower 106 that is suspended from the plate 102 by means of a bolted connections 108 and whose outlet communicates with the interior of the condenser hood 100 in order to direct coolant air in heat exchange relation with respect to the refrigerant fluid flowing in the tubes of the condenser coil 96.

[0031] As shown, the shroud 100 housing the condenser coil 96 is disposed in an elevated position at the rear of the chassis 14 whereby the blower 106 is contained in a plenum 110 formed beneath the condenser coil 96. A liquid collection pan 112 is disposed at a somewhat elevated position in the plenum 110 and operates by means of a transfer tube 113 to receive liquid which collects in the tray 92 for collecting condensate generated on the tubes 88 of the evaporator coil 86.

[0032] From a consideration of FIG. 3 it will be appreciated that, with the chassis 14 installed within the cabinet 12, its rear end, that contains the condenser heat exchange unit 94 and underlying chamber 110, is caused to abut the building outside wall 44. A plate 114, which forms the back side of the chassis 14, contains openings for the passage of air. The lower portion of the plate 114 contains opening 116 for the reception of fresh outside air which is directed from wall opening 48 beneath the liquid collection panel 112 through an opening 118 at the bottom end of the partition plate 72 and into the evaporator section 68 of the chassis 14. Such outside air is submitted to processing in the evaporation section 68 prior to discharge into the space to be ventilated. Another opening 117 communicating with the wall opening 48 above the liquid collection pan 112 is adapted to conduct fresh outside air into the condenser section 70 for cooling refrigerant in the tubes of the condenser coil 96.

[0033] According to this described arrangement, the cooling air is induced by the action of the blower 106 to enter the plenum 110 and to flow across the surface of the liquid in the collection pan 112 where it withdraws moisture which is blown in mixed relation with the air into the chamber formed by the condenser shroud 100 to pass in heat transfer relation with respect to the tubes of the condenser coil 96 before exiting through opening 119 in the back plate 114 of classis 14 and the air discharge opening defined by the upper opening 46 in the building wall 44. It will be appreciated that a more effective transfer of heat between condenser refrigerant and cooling fluid is effected by the mixture of moisture with inlet air passed to the condenser coil 96 in that the evaporative effect of the moisture carried by the air is utilized for extracting heat more effectively from the refrigerant.

[0034] Process air to the ventilator 10 includes, besides the aforementioned fresh inlet air, which enters the chassis 14 through the lower air opening 116 and enters the evaporation section 68 through the opening 118 in the partition plate 72, also return air from the ventilated space which passes through the return air grill 52 in the cabinet 12 and to the evaporator section 68 through opening 120 in an inclined face of the chassis front wall 58. The process air which enters the ventilator chassis 14 is filtered by readily removable sheet filters including fresh air filter 122 and return air filter 124.

[0035] A movable partition plate 126 is disposed between the filters 122 and 124 and has as its principle function to assist in the separation of the outside air flow path from the return air flow path. The partition plate 126 is pivotally mounted on the chassis base 24 by means of a pivot pin 128 which permits forward pivoting of the plate when a wing grip 130 thereon is manually grasped. Thus, folding of the partition plate 126 enables easy access to the fresh air filter 122 along with access to the return air filter 124 for filter repair or replacement upon removal of the front panels on the cabinet 12 and chassis 14, respectively.

[0036] Control of flow of inlet air to the ventilator 10 is provided by a roll damper 132 that is connected for pivotal movement between vertical support plates shown at 134 in FIG. 5. The roll damper 132 includes end brackets 126 (only one of which is shown in the drawing figures) which are suspended by means of pivot pins 138 from the respective support plates 134. A damper plate 140, shown to be of V- or chevron-shape is carried between the end brackets 136 and extends substantially coextensively with the combined length of the blowers 78. It will be appreciated, as best indicated by FIG. 3 of the drawing, that with the roll damper 132 positioned as represented by the solid line figure, inlet flow of process air to the ventilator 10 will be outside air which flows through opening 48 in building wall 44, and thence through openings 116 and 118 in the chassis back plate 114 and partition plate 72, respectively, to the inlet (not shown) of the blowers 78, whereby the air is passed through openings 79 under pressure to the evaporator section 68 for ultimate discharge into the space to be ventilated through the discharge openings 67 and 40 in the roofs of the chassis 14 and cabinet 12, identified by reference numerals 64 and 36, respectively.

[0037] Alternatively, with the roll damper 132 pivoted to the left, as shown by the broken line representation in FIG. 3, total process air flow to the ventilator 10 occurs via the return air openings 52 and 120 in the cabinet 12 and chassis 14, respectively, whereby air flow, after passing through the openings and filter 124 is forced by blowers 78 into the evaporator section 68 and thence from the ventilator via the openings 36 and 37 as processed air to the ventilator space.

[0038] With the roll damper 132 positioned as best shown in FIG. 5, at a mid-point position between the openings 52 and 118, process air delivered to the evaporator section 68 of the ventilator is a combination of both fresh inlet air from the outside and return air from the ventilated space which passes through grill 52 in the cabinet 12 and the opening 66 in the chassis 14. The position of the roll damper 132, which is effected by means of the operation of a proportioning motor (not shown), determines the composition of the process air admitted to the ventilator 10.

[0039] The modular unit ventilator 10 is typically installed in a room or space to be ventilated with the back end of the cabinet 12, that is essentially open, abutting an outside building wall 44, or the like. With the front panel 16 of the cabinet removed, the chassis 14 is installed in the cabinet 12, the chassis being slidingly supported on support rails 28 between a pair of spaced cabinet side plates 32. The detachable electric plug 18 is connected to a jack on the chassis side wall 62 with the wire thereof being connected to the control box 54 attached to the adjacent cabinet side plate 32.

[0040] In ordinary operation in which air is to be treated by an air conditioning process before being discharged into the space to be cooled, a fluid refrigerant, such as the typical HCFC refrigerant, R-22, is circulated continuously in an essentially closed cycle through the tubes 88 of the evaporator coil 86, the compressor 97 and the tubes of the condenser coil 96. As shown, a gas by-pass valve 91 is provided in the refrigerant circuit in order to prevent overload of the compressor 97 by bypassing excess gaseous refrigerant to the condenser coil 97. Outside air to be treated is admitted to the unit ventilator through opening 48 in the building wall 44 whence it flows serially through the opening 116 in the chassis back plate 114, opening 118 in the partition 72, entering the evaporator section 68 through filter 122 in the lower region of the section before being conducted via blowers 78 through the evaporator coil 80 to be cooled via evaporative cooling by the refrigerant flowing through the evaporator tubes 88 and exiting the unit ventilator through the openings 67 and 40 in the chassis 14 and cabinet 12.

[0041] It should be appreciated that, simultaneously with the flow of outside air induced by blowers 78 through the evaporator section 68 of the unit, a flow of outside air is also induced by blower 106 in the lower region of the condenser section 70 whereby outside air passes through the lower opening 48 in the building wall 44, through the opening 120 in chassis back plate 114 to the blower 106 from whence the air flow is directed into the plenum 110 formed by the condenser hood 100, being directed in heat transfer relation with the condenser coil 96 to condense the refrigerant contained in the condenser tubes before existing the chassis through openings 119 and 46 in the chassis back plate 114 and the building wall 44, respectively.

[0042] According to the invention, evaporative cooling of the condenser coil 96 contributes to a liquid drain-free construction produced by the fact that condensate removed from the process air, which forms on the outside surface of the evaporator tubes 88, is conducted downwardly by gravity and is collected in the condensate collection tray 92 which underlies the evaporator coil 86. This condensate is conducted via transfer tube 113 to the liquid collection pan 112 that divides the plenum 110 in the lower region of the condenser section 70 of the unit. As the open upper side of the collection pan 112 is exposed to the condenser cooling air flow entering the chassis through the opening 117 in the chassis back plate 114 the air mixes with moisture from the liquid in the pan 112 thereby providing additional cooling capability for the condenser cooling air as well as evaporating the liquid effluent from the treatment process whereby no liquid drain from the unit ventilator is required.

[0043] The versatility of the present invention is manifest by the fact that, in addition to the treatment of outside air, recirculated return air from the ventilated space can also be treated, either alone or in mixed relation with outside air delivered to the unit. Thus, with the roll damper 132 disposed in the position shown by broken lines return air from the ventilated space is admitted to the unit for processing in the manner previously described through the return air openings 66 in cabinet 12 and 120 in the chassis 14 and filter 124. A controlled mixture of fresh outside air and return air can be admitted to unit by merely adjusting the position of the roll damper 132 between the illustrated left and right hand positions.

[0044] Further, the described unit ventilator 110 can, depending upon ambient air temperatures, alternatively be operated, with the evaporator and condenser rendered inoperative, by allowing fresh air to be induced by the blowers 78 and blown as a forced air flow into the ventilated space. Or the unit ventilator 110 can be used as a room air heater by the provision of air heating apparatus shown in FIG. 3 as an electrically operated heater 95 or a hydronic heater 93.

[0045] As best shown in FIG. 6, the unit ventilator 10′ of the invention contemplates the use of multiple chassis 14′ in a cabinet 12′ of elongated length in order to accommodate reception of plural chassis, typically two, which may have the same or different capacities. As for example, where individual chassis having air treatment capacities of 20,000 Btu, 24,000 Btu and 32,000 Btu, respectively, are provided, it will be appreciated that, through the provision of plural chassis in a cabinet, modular production of unit ventilators having Btu capacities of 40,000, 44,000, 48,000, 52,000, 56,000 and 64,000 can be provided.

[0046] Furthermore, an additional benefit derived from the production of unit ventilators 10′ utilizing plural chassis within a cabinet is that, in the event of a need to remove one chassis from service, as for example for maintenance or repair purposes, the unit ventilator is able to remain operative, albeit at a reduced capacity level.

[0047] As a result of the hereindescribed invention there is provided a modular unit ventilator of improved construction and design whereby air ventilation for large spaces, such as school rooms, or the like, is more effectively achieved through the use of equipment which is characterized by reduced production and operation costs.

[0048] While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.