US2043561A

US2043561A - Apparatus for controlling and indicating air volume

Info

Publication number: US2043561A
Authority: US
Inventors: James E Sims
Original assignee: Reconstruction Finance Corp
Current assignee: Reconstruction Finance Corp
Priority date: 1932-08-25
Filing date: 1932-08-25
Publication date: 1936-06-09
Anticipated expiration: 1953-06-09

Description

Jime 9, 1936.

APPARATUS FOR CONTROLLING AND INDICATING AIR VOLUME Filed Aug. 25, 1932 7 Sheets-Sheet 1 1n ol INI/ENTOA @am /I TZORNEY Juneg, 1936- J, E, s|M5 2,043,561

APPARATUS FOR CONTROLLING AND INDICATING AIR VOLUME Filed Aug. 25, 1952 '7 Sheets-Sheet 2 IU'HHI' H HMH' HHH! Il H A TTORNEY June 9, 1936. J. E. slMs 2,043,561

APPARATUS FOR CONTROLLING AND INDICATING AIR VOLUME Filed Aug. 2:5-, 1932 PfsheeJs-s11-eet s Ibi/3.6. "n H7 @l 71 70 '72 /N VENTO/e W JAW June 9, 1936. J. E, SIMS 2,043,561

APPARATUS FOR CONTROLLING AND INDICATING AIR VOLUME Filed Aug. 25, 1932 7 Sheets-Sheet 4 1n 1oz 106 WEA/TUR ma ww f5 .4 TURA/5 y June 9, 1936. I J. E. slMs 2,043,561

APPARATUS FOR CONTROLLING AND INDICATING AIR VOLUME Filed Aug. 25, 1932 vsheets-sheet 5 lllllllll IIJNB I Ill. I lrmnwllbunlllllllll |I|I.|I| I||NIII|| |II lllllll.

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APPARATUS `FOR CONTROLLING `AND INDICATI'NG AIR VOLUME g f/KENTo/e W Mm 7 'l 7A TTORNEY June 9, J. E. slMsl 2l,043,561

APPARATUS FOR. CONTROLLING AND INDICATING AIR VOLUME Filed Aug. 25, 1932 7 sheets-sheet 7 Ijg. 17.

tamed June a, 1936 UNITED STATES PATENT OFFICE APPARATUS FOR CONTROLLING AND INDICATING A1B VOLUME corporation Application August 25,1932, Serial No. 630,421

is claims.

This invention has reference to heating and Ventilating units and, particularly, relates to means, devices or apparatus for controlling, metering or measuring both recirculated and fresh air and indicating the amount of recirculated and fresh air to be or being, treated in the unit and delivered to the room of installation of the unit.

It is well known that legal requirements and local ordinances compel the use, in certain public buildings, such as school-houses, of heating and Ventilating apparatus which will `deliver to each room a definite number of cubic feet of fresh air per person. To meet the requirements, Various apparatus and units have been devised; but, none has been able to constantly and fully meet the requirements in` varying temperatures and outside conditions. Inlet and recirculating dampers have been variously controlled in the units, and various combinations of known means have been utilized; but, no satisfactory means, prior to my invention, have been found to furnish the necessary cubical supply or fresh air and deliver the same constantly, to the room of installation of the unit. And in no instance has it been possible, prior to my invention, in any system of heating and ventilation, to gage and ascertain the amount or volume of air passing through the unit and, at the same time, control the fresh air content of such volume under any and all outside weather conditions.

According to my invention, `a controller has been provided, for heating and Ventilating units, which performs the important function of controllingtheamount of fresh outside air which is being supplied during a predetermined period to the room of installation of the unit, according to the mode of adjustment of the controlling means, and also the inlet damper of the unit. With my invention applied to a heating and Ventilating unit, whether of the automatic or hand operated type, I am able to obtain efiicacious operations and important functional results which will be fully disclosed hereinafter. l

In order that my iinvention may be clearly understood I havel provided drawings wherein:

Figure 1 is a View in front elevation o f a heating and Ventilating unit having my invention for automatically metering and controlling the amount of fresh air admitted to the unit .applied and indicating the amount of fresh air admitted to the unit;

Figure 4 is a sectional view taken on the line 4--4 of Figure 3;

Figure 5 is a transverse sectional view taken on the line 5 6 of Figure 3;

, Figure 6 is a fragmentary sectional view taken on line 6-6 of Figure 3;

Figure 7 is a fragmentary transverse sectional view taken on line 1-1 of Figure 3;

Figures 8 and 9 are transverse sectional views taken, respectively, on lines 8-8 and V9-9, of Figure 3;

Figure 10 is a wiring diagram of the apparatus;

Figure 11 is a view in iront elevation of' a unit, similar to that of Figure 1, showing my handcontrolled means for admitting fresh air to the unit and for indicating or metering or measuring the amount of fresh air admitted;

Figure 12 is a view in-sectional end elevation of the unit shown in Figure 11;

Figure 13 is a view in front elevation, with parts broken out and in section, of my velocimeter, that is, my instrument for indicating or metering or measuring the amount of fresh air admitted to a hand-operated damper unit;

Figure 14 is a view in elevation of one end of the velocirneter;

Figure 15 isa transverse sectional view taken on the line l5-I5 of Figure 13;

Figure 16 is a vertical sectional view taken on the line lli-I8 of Figure 13; and

Figure 17 is a schematic plan view illustrating the velocimeter as utilized in a central fan control system.

Referring tothe drawings and particularly Figures 1 to 10, the reference numeral 20 designates the casing of a known form of heating and ven- .tilating unit. Communicating with the lower part of the casing is a fresh air inlet 2 I, which is provided on its outer end (not shown) with the customary louvers and screen. The fresh air inlet leads into a part of the casing above the damper 26termed the lower mixing chamber 22. Extending across the front of the unit and also in communication with the chamber 22 is the recirculation opening 23 which is enclosed by a grille casing 24. Pivoted at 25, in the chamber 22, is a damper 26 which, in one'extremelposition,'closes thefresh air inlet 2l (see Figure 2) and in the other extreme `position closes the recirculating `opening .23. In any of its intermediate positions, depending upon where thedamper'is located, the proportions of fresh air and recirculated air may be varied.

Situated above the lower mixing chamber 22 is the fan chamber 21. A pair of suction fans and casings 28 are positioned in this chamber and the fans are driven by a motor 29, Figure 1, which is mounted between the fans. Air is drawn in through the eyes or ends 30 of the fans and is expelled through openings 3| in a partition 32 into the upper chambers.

Adjacent the bypass chamber 33 and separated therefrom by a partition 34 is the heating charnber 35 in which is mounted the heating elements or radiators 36. Pivoted at the lower edge of partition 34 is a mixing damper 31. This damper may be operated by thermostatic or other suitable means; but, as said means form no part of the present invention, they are not illustrated. It will be apparent from an inspection of the drawings that, depending upon the position of the mixing damper 31, all the air may be directed to the upper mixing chamber 38, through the bypass chamber 33, or through the heating chamber, or any desired proportionate amount,

, depending upon the temperature outside or inside the room, may be directed through the heating chamber and the bypass chamber and mixed in the chamber 38.

The air passes through the mixing chamber 38 from whence it passes through an outlet opening 39 covered by a grille 40. The apparatus described up to the present time comprises a suitable type of heating and Ventilating unit. There are different forms of heating and Ventilating units, and it is to be understood that my invention hereinafter described is readily applicable to all such known forms.

It is an important problem in the operation of heating and Ventilating units to insure the proper amount of fresh air being admitted to the unit. In classrooms, where a large number of pupils is gathered, it is essential for their good health to be able to control and readily ascertain the amount of fresh air entering the unit. Where only a few pupils are in the class-room, the amount of fresh air admitted to the unit may be reduced materially and thus, particularly in cold weather, economies may be effected and the health of the students always guarded.

The instrument used for metering and automatically controlling the fresh air admitted to the unit, is termed Ia velocistat. It is referred to generally by the reference numeral 4l, Figures 1 and 2, and is shown in detail in Figures 3 to 9.

' The mechanism is carried by a frame comprising a base 42 and upstanding, supporting

members

43, 44 and 45. Pivoted between the

members

43 and 44 is a vane 46 in the form of a blade of considerable area and made of thin, light material so as to be very susceptible to air currents. The vane is secured to a pintle 41 which in turn is pivoted in

anti-frictional cone bearings

48 and 49 mounted,.respectively, in the

members

43 and 44. The bearing 48 has threaded engagement with the member 43 so as to be adjustable, and when it is properly positioned is held by a lock nut 56. Means are provided for perfectly balancing, or placing in a state of equilibrium, the vane 46; that is to say, the vane is so 'balanced that, when turned on its ne pivots, it will stay in any position it may be primarily set unless it is moved by a current of air. 'I'his balancing means comprises a pair of weights 5l Aand 52 mounted on that part of the vane below the pintle. Obviously, the same result could be accomplished if the vane were of exactly the same area and weight on either side of its pivot. However, to insure the proper area for contact with the air currents, the velocistat would be entirely too high and bulky if this arrangement were adopted. -The weights approximately offset the additional weight of the Vane on the upper side of the pivots. However, in order to insure the extremely delicate balance that is desirable, the weights, which are mounted on either side of the lower part of the vane, are pivoted at 53, Figure 3, and may be moved in an arcuate path. When the proper balance is obtained, the weights are held in position by a set screw 54 which passes through the arcuate slot 55 and has threaded engagement with the weight 52, (see Figure 5).

The vane 46 carries a contact finger 56, the function of which will be hereinafter described. An adjustable counterweight is provided to work in conjunction with the vane 46. The adjustable counterweight comprises a block 51 freely mounted to swing independently on the pintle 41. The block terminates in a threaded stem 58,

on which an ladjusting nut 59 is threaded. A set screw 66 passing through the block is adapted to contact with the weight 52, Figures 3, 4, and 7, which extends laterally beyond the slotted-end of the vane 46.

From the foregoing it will be apparent that, depending upon the angular position of the vane, more or less eifort or pressure willfbe required to turn it. The adjustment of the counterweight may be very finely regulated by moving the nut 59 on the stem 58 and by positioning the se screw 60.

As shown in Figures 5 and 7, the counterweight is so positioned that a current of air, being drawn or blowing in the direction of the arrow a. in Figure 5, will have to be comparatively strong to shift the vane 46. As the vane is moved to the right, or clockwise, in Figures 5 and '7, the counterweight 51 will exert less eiort on the vane and, therefore, a smaller air velocity will shift the vane. The reverse of this is true if the vane is moved to the left in Figures 5 or 7, that is, as pressure is reduced on the vane, the counterweight will move the vane reversely. Walls 6l extend upwardly between the

upstanding members

43 and 44 and act as shields to prevent the air currents engaging and inuencing the vane below its pivot and thereby tending to cause -an unbalanced condition.

Secured to the upstanding member 44, on the side opposite the vane 46, is fixed a curved indicator or gage-plate 62, suitably graduated as at 63 in Figure 4. traverse the gage-plate 62. Means, hereinafter described, are provided for moving the pointer and thereby indicating the setting of the velocistat which, inturn, controls the admission of fresh air into the unit and the amount thus admitted. The pointer 65 is carried by an arm 66, which is pivotally mounted on a stud 61, supported on the member 44. The cone bearing 49 is formed in a reduced threaded portion of the stud 61, which passes freely through an opening in the member 44 and the stud is rigidly held in position by a nut 66. A nut and washer 69 on the opposite end of .the stud confine the arm 66, which is made of insulating material such as bakelite or hard rubber. In addition to the pointer 65 arm 66 carries two contact members 10--10 (see Figure 6) which in turn have threaded therein contact screws 1|-1l for c-operation with the contact finger 56 carried by the vane 46. 'I'he contact members 16 are held in posi- A pointer 65 is adapted to amasar ing diagram. The contact finger 56 passes through a curved slot 'M in the member 44.

Means are provided for adjusting the position` `a block 76 which is swiveled therein and has an internally threaded aperture and acts as a nut for the adjusting screw 16. This adjusting screw passes freely through another block 'il which is swiveledin the member 45, as indicated at 'i8 in Figures 3 and 4. The adjusting screw 'i6 has a iiange 'i9 which engages one side of the swiveled block 'l1 and a collar 80 engages the opposite side of the swiveled block. Thus, longitudinal movement of the adjusting screw is prevented and, when it is rotated, the arm 66 will be moved in one direction or the other depending upon which way the adJusting screw is turned. The end of the adjusting screw beyond the ange 'l0 is squared as at 8i to accommodate a socket wrench for rotating the screw.

The operation, in connection with other parts of the invention, will now be described, and for this purpose particular attention is directed to Figures 1 and 2, and the wiring diagram of Figure 10.

The velocistat 4i, through its electrical contacts 'lla- 1lb and contact finger 56 will operate Aa, reversing motor 82, in one direction or the other. The reversing motor, through suitable reduction gearing, well known to one skilled in the art, will move the arm B3 in one direction or the other. The arm 83 is connected by a link 84 with another arm 85 secured to the trunnion or pivot 25 of the damper 26. Thus, whenever thereversing motor is operated, the damper will be moved in one direction or the other.

The velocistat may be positioned in any part of the unit where it is in the path of an air stream. However, it would not be visible if it were placed in the fresh air inlet 2|, or chamber 22, and more or less involved mechanism would have to be utilized to employ the control and display the'reading. It has been found in practice that the most advantageous position in which to place the velocistat is in the recirculation opening 23, behind the grille 24 and substantially below the eye 30 of one of the fansf28. This position is indicated in Figures 1 and 2.

The suction fans deliver a predetermined amount of air through the outlet opening 40, at the top of the unit, into the room. By way of example, this amount of air might be said to be 1200 cubic feet per minute. As stated, this amount will be delivered constantly or as long as the fans are in operation and irrespective of the position of the damper 26. If the damper 26 were in the position as indicated in Figure 2,

the 1200 cubic meet per minute would be recirculated air, drawn into the front of the unit at 23, from the room of installation. If the damper were moved to the other extreme position, the 1200 C. F. M. would be fresh air, drawn through the inlet 2| from the outside of the building. Obviously, in an intermediate position of the damper 26, the 1200 C. F. M. would be a mixture, proportionally, of fresh air and room air. The velocistat is so calibrated that when the pointer 65 is on the 200 graduation of the

plate

62, 200 C. F. M. of room air is being drawn into the unit and delivered together with 1000 C. F. M. of fresh air. When the pointer 65 is on the 400 mark, 400 C. F. M. room air and 800 C. F. M. of fresh air is being drawn into and delivered from the unit. When the damper 26 is automatically 5 controlled and the velocistat is set for a predetermined air' mixture, the unitwill deliver this desired proportion of fresh air and room air, indefinitely, regardless of varying outside weather conditions. According to varying conditions of 10 the outside atmosphere, the velocistat 4E and the inlet damper motor 82 will interact and cooperate to shift the damper 26 to cause it to maintain the desired conditions in the unit and in the room of installation of the unit. If the 15 wind increases in velocity, while the damper 26 is open, the intake of fresh air will increase as compared with room .air and the velocistat will immediately act to reverse the motor 82 and commensurately close the damper 26 at the fresh :zo air inlet 2 Il. If, subsequently, the room temperature becomes too low, the thermostat, controlling the inlet damper, will close the latter so as to permit all recirculated air to pass through the heating element 36, until the proper tem- 25 perature is restored in the room of installation. Thus, in an automatic unit, the thermostatic control excludes all fresh air from the room of installation of the unit should the temperature of that room fall below the setting of the 30 thermostat.

The amount of intake of fresh air and room air is controlled by the velocistat, and the shifting of the duplex damper (intake and recirculating) is motor controlled. The non-automatic unit is 35 an alternative form and will be presently described.

The automatic control of the velocistat is brought about by thev impact of the air, passing through the grille 23, upon the vane 46, which lo will move, according to variations in pressure, the finger 56 against one of the contact screws Ha-1lb, close the motor circuit, and cause the motor 62, to function to shift the damper 26 the required amount to maintain the proper propor- 45 tions of fresh air and room air entering the unit, and this without altering the required cubical air footage discharged from the top of the unit.

'In Figure 10, the casings 20 of two heating and Ventilating units, for example, are disclosed. There may be as many of these units as there are rooms in the school or building, although the invention is applicable to a single unit. The velocistats are indicated dlagrammatically at 4| and thereversing motors at 82. 'Ihe fan motors are also shown diagrammatically at 29; but, it is to be understood that their circuits are separate fzom the circuits controlling the reversing motors 8 see also Figure 1, at one end thereof, which may Y be set for fresh air or mixed air. When set for fresh air, the fresh air dampers 26 will open or be in the other extreme position from that deslgnated in Figure 2. When set for mixed air, the fresh air dampers will be under control of the veloclstats. Each of the units is also provided with afan switch 8l, on the outside of and at one end of the unit casing, as also shown in Figure 1, for controlling the fan motor circuits. The switchboard 88 is preferably positioned in the janitors, or superintendent's, quarters. It carries a switch 89 which may be set to control the position of the fresh air dampers in all of the units. When this switch is in the "shut position, or on Each of the units is provided with a

switch

86, 60

the contact 90, all the fresh air dampers in the units will be closed, or in the position of Figure 2,

regardless of the setting of the swtches 86 on the units. 'I'his is important because at night, or on holidays when the rooms are unoccupied, it is essential that the fresh air dampers be closed to prevent the cold air entering the room and dolng damage by freezing. When the switch 89 is in the open position, or on the contact 9|, the switches 86 on the units will govern the operation of the fresh air dampers as heretofore described.

A common switch (not shown) for controlling all the fan motors may also be positioned at the control station. The parts are so arranged and wired that should the janitor open the common switch, or switches 81, which shuts off the fan motors, and neglect to throw the board switch 89 to the shut contact 90, the fresh air dampers will close if the switches 86 on the units are turned to the mix contact, because the vane 46 of the velocistat will shift to motor reversing contact and cause the motor 82 to actuate the damper 26 to the position to shut out all fresh air. This is due to the fact that the stoppage of the fans practically eliminates impact of air upon the vane of the velocistat, which vane thus returns to normal position. If the switches 86 on the units are set on the fresh contact, the dampers 26 will remain open until the temperature of the rooms lowers to the setting of the thermostats indicated at 92, there being a thermostat for each unit. The thermostats may be set for example at 67 F., and will always close the fresh air dampers 26 regardless of the setting of either the switches 86 on the unit or the switch 89 on the main control board.

Sometimes it happens that the operator or janitor desires to recirculate air in one or more rooms which are not occupied and at the same time leave steam in the radiators 36. In such case, he shuts off the fan motor switch 81 at the unit and leaves the unit switch 86 on the mix contact.

The fresh air damper 26, under control of the velocistat and motor 82, will then close against the incoming air, as stated in the foregoing, regardless of the operation of the other units in the system.

Referring to the wiring diagram more specifi- '.cally, the mains are indicated at 93 and 94. The

fan motors 29 are directly connected by

leads

95 and 96 and through switches 81 with the

high power mains

93 and 94. Leads 91 and 98, from the mains, run to a transformer 99, where the voltage is stepped down. A switch is interposed between the transformer and the

mains

93 and 94. The wires |0| from the transformer have taps |02 which lead to-one of the posts of the reversing motor which is grounded on the motor casing as at I 03, the motor in turn being grounded to the unit casing 20 as at |0311. The leads |04 have taps which lead to another of the posts on the reversing motor 82. A pilot light |06 is connected between the leads |0| and |04. Thus current is supplied to the motors 82. Wire |01 runs from the open contact 9| of the switch and has taps |08 leading to posts on the reversing motor to drive the motor in a direction to open the fresh air damper when the circuit is completed by the velocistat. Lead |09 runs from the shut contact 90 of the main switch 89 and has taps I0 leading to one of the contacts of the thermostats 92 and from there other leads connect with wires 2 which lead to other posts on the reversing motor and to the mix contact ||3 of the unit switches 86. Leads ||4 from the switch Y pole contact have taps ||5 running to the other contacts of the thermostats 92 and from there through the ngers ||6 of the thermostats to leads |1 which run to the contacts 1|a of the velocistats. The leads ||1 also have connections ||8 with the fresh air contact ||9 of the unit switches 86. Leads |20 connect the switch pole contacts of the unit switches with the other contacts 1lb of the velocistats. The blades 46 of the velocistats which carry the contact fingers 56 are grounded as indicated at |2|, the heating and Ventilating unit thus forming the other leg of the circuit.

If the gage 65 of the velocistat is set a trifle beyond 400, as indicated in Figure 4, the contact finger 56 will engage the contact 1|a and the fresh air damper will open until such time as a volume of air of somewhat more than 400 C. F. M. are being admitted through the recirculating opening. When this point is reached, the contact finger 56 will be poised between the contacts 1|a and 1lb and remain there unless some outside increase in air velocity disturbs its equilibrium. The contact finger will then be forced against the contact 1lb and the motor reversed to close the fresh air damper a sufficient amount to again maintain the balanced condition.

Figures 11 to 16 illustrate a simpler form of my invention and one which is particularly applicable to hand-controlled heating and Ventilating units. The general arrangement of the unit illustrated in Figures 11 and l2 is similar to that shown and described in Figures 1 and 2, and the same reference characters are applied to similar parts, so it will not be necessary to enter into a detail description thereof.

In this form of my invention, the volume of room air as compared with fresh air, entering the unit, is indicated by a form of device which I have termed velocimeter to distinguish it from the velocistat or automatic form of my invention. The velocimeter is devoid of the electrical contacts and is thereby greatly simplied. Instead of the damper 26 being controlled by a motor, as in Figures l and 2, a hand controller is used, as shown in Figures 11 and 12. A short arm |5| is secured on the inner end of the stud on which the handle |50 is mounted. A link |52 connects the arm |5| to another arm |53 secured to the pivot 25 of the fresh air damper 26. It will thus be apparent that as the control handle |50 is moved, the fresh air damper will be opened or closed allowing more or less fresh air to enter the unitl as compared with room air passing the device |54.

It is desirable to meter or actually ascertain the amount of fresh air entering the unit, and accurately indicate the same; so the velocimeter is employed and is located in the unit at the same point as the velocistat. The blade 46 and its pintle 41 are pivoted in a similar manner. The same balance weights 5I and 52 are utilized, and the counterweighting means 51, 58, 59, and 60 are similar. However, the vane 46 carries an indicator |55 which passes through an opening |56, in the wall 44, and traverses the indicator plate 62 which is graduated in a similar manner to the same plate on the velocistat. Both the velocimeter and velocistat ma" be covered or partially covered by a protecting mesh as indicated at |51, in Figures 3 and 13. This is primarily to prevent children, in a schoolroom, from tampering with the instruments.

The'fresh air damper 26is manipulated by hand and when it is opened a certain amount,

the operator glances at the velocimeter and notes the amount of recirculated air being delivered to the unit. the damper is clos-ed somewhat and the velocimeter again inspected. If an insurhcient amount of fresh air is being delivered and these adjustments of the damper are continued, guided by the velocimeter, until the proper proportions of room and fresh air have been reached, the damper is then set. It is, of course, understood that, with the fans in operation, suction of air is caused through both the grille 2d and intake 2|, and that the damper, actuated by hand, regulates the intake of air at front and back of the unit, and that the amount of intake of room air is immediately indicated on the gage-plate 62 of the velocimeter and quickly read with facility through the grille 2li, enabling approximately' accurate adjustments to be made, and the health and comfort of the occupants of the room are always guarded.

The velocistat and velocimeter may be used in numerous Ways. For example, in Figure 17, a schematic illustration is given of the velocimeter applied to a central fan system. Therein the reference number iGli designates the chamber in which the fans and other apparatus are or may be housed. A series of conduits IGI may lead to separate rooms, or to heating and Ventilating units, or to other devices requiring air. The conduits are provided with dampers |62, and beyond the dampers are located the velocimeters |54. 'I'he reading of the velocimeters is taken through openings which may be covered by a transparent material |63. It will be apparent that the dampers may be regulated in accordance with the amount of air required and the amount passing through the various conduits may vary and may he readily ascertained by reading the velocimeters.

The foregoing represents certain of many arrangements in which my invention-may be used,

and the system in use, or to be used, will deter- It will be understood, from the foregoing. that the calibrations on the segment 62, indicate specifically the volume of room air rushing into the inlet 23 through the grille 24 under-suction from the rotary fans and knowing the volume of air which is being delivered through the grille 39, it requires merely an easy mental calculation to ascertain the amount of cold air rushing into the inlet chamber -22 to he mixed with the room air and discharged by the fans through one or more of the chambers above the latter and thence through the grille 39. It will be understood, however, that the calibrations can be reversed on the plate 62 so as to indicate directly the amount of fresh air entering the inlet chamber 22. In any event, the importance of both my velocistat and velocimeter is to control and ascertain the amount of fresh air being discharged into the room of installation through the unit in the predetermined volume which is so discharged. However, it will be further understood that the room air, in accordance with the forms of my invention disclosed herein is ordinarily the medium which is utilized for operating the vane of both the velocistat and velocimeter.

If this amount'is too much,

While I have shown and purpose claiming my velocistat and velocimeter in combination With a heating and Ventilating unit, or heating and Ventilating system, I desire it understood that other uses thereof may be made in the matter of measuring, indicating and controlling, automatically or otherwise, the volume of air or gases impinging upon or passing the same. And while I have, in the foregoing description, used the room air impinging upon the velocistat as a medium by which to gage or determine the amount of fresh air entering the unit, I may reverse this operation and calculation by utilizing the-fresh air or outside air entering the unit as the medium by which to determine or gage the amount of room air entering the unit; or I may make the calibrations 63 indicate the amount of fresh air entering the unit, and thus by easy calculation determine the amount of room air entering the unit.

I desire it understood that I purpose claiming, for the foregoing reasons, my velocistat and velocimeter independently of any system or apparatus and in such terms as will necessarily involve and encompass the generic idea of means, operation and function of the two forms of my device.

Having thus described my invention, what I claim and desire to secure by Letters Patent isz- 1.A heating and Ventilating unit having an air inlet chamber at or near its bottom, open at both front and rear, a single damper mounted in said inlet chamber in position to enable it to control both said openings, and means for actuating said damper including a device located at one of the openings and susceptible to operation by the power of the air entering said opening.

2. A heating and Ventilating unit having an inlet chamber at or near its bottom having openings at its front and back, a damper mounted in said chamber and adapted to close the openings, and pneumatic means located at the front opening for controlling the position of the damper and simultaneously indicating the volume of air entering the unit through one of said openings.

3. A heating and Ventilating unit having an air chamber at its bottom, provided with openings at its opposite sides for the admission of fresh and recirculated air respectively, a damper mounted in said chamber and adapted to close the openings; pneumatic means, operated by a part of the air volume entering the unit, for automatically controlling the position of said damper when the temperature of the room of installation of the unit is at or above a predetermined number of degrees, and thermostatic means for automatically actuating the damper to close the fresh air opening in the unit.

4. A heating and Ventilating unit having an inlet chamber at or near the bottom, having openings at its opposite sides for the admission of fresh and recirculated air respectively, means for drawing the air through these openings, a damper shiftably mounted in said chamber, pneumatic means operated by a part of the air volume entering the unit for automatically controlling the position of said damper, said pneumatic means being adapted to automatically actuate the damper to close the fresh air opening when the aforesaid means for drawing the air through the unit openings has been made inoperative. i

5. An instrument for metering, indicating and controlling the amount or velocity of air or gas passing through an opening substantially as outlined in claim 9, wherein a vane is provided' with a pointer and there are oppositely disposed electrical contacts .insulated from the vane between which the pointer operates.

6. A device such as deilned in claim 9, wherein the casing is provided with an indicating plate, has a plvotally mounted pointer adapted to travel relatively to the indicating plate, and the pointer is shifted relatively to a pair of electrical contacts.

7. A heating and Ventilating unit having air inlets at back and front, and an air discharge at its top, a damper mounted between the two inlets and adapted to close the same alternately, a motor and connections to the damper for actuating the same, and means located at one of the inlets for actuating the motor including a pneumatic controller.

8. A heating and Ventilating unit such as dened in claim 7 wherein the pneumatic controller is provided with means to open and close the motor circuit so as to reverse the same.

9. In combination with a heating and ventilating unit having an inlet opening, a pivotally mounted inlet damper, an instrument for metering the air admitted to the unit mounted in the inlet opening of the unit, and means actuated by the metering instrument and connected to the inlet damper for actuating the latter and for controlling the operation of the metering instrument.

10. A heating and Ventilating unit having air inlets at back and front, and an air discharge at its top, a damper mounted between .the two inlets and adapted to close the same alternately,

a motor and connections to the damper for passing through the casing.

actuating the same, and means located at one of the inlets for actuating the motor including a pneumatic controller having means causing it to open and close the motor circuit under the impulse of varying volumes of air entering the unit.

11. In combination, a casing of a heating and Ventilating unit having a normally open recirculating inlet at its lower` front, a damper for controlling the admission of air into said unit, and means for operating said damper, including a device arranged at the said inlet and susceptible to and operated by the power of a part of the air volume entering the unit at said inlet.

12. A heating and Ventilating unit having an air inlet chamber at or near its bottom open at opposite sides, a single damper pivotally mounted in the bottom of the unit between said openings and adapted to control both thereof, operating mechanism for said damper, and a device for controlling the operation of the damper located at one of the openings and having means susceptible to operation by the entering air, and connections between said device and the damper operating mechanism. l

13. In combination, a casing of a heating and Ventilating unit having a recirculating opening at its lower front, and a fresh air inlet, means for eiecting movement of a predetermined volume of air through said casing, and means controlled by the movement of air into the casing for regulating the amount of fresh air of said volume JAMES E. SIMS..