US20100304659A1

US20100304659A1 - Calibrated airflow measurement system for a ceiling vent

Info

Publication number: US20100304659A1
Application number: US12/476,324
Authority: US
Inventors: Bart Petterson
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-06-02
Filing date: 2009-06-02
Publication date: 2010-12-02

Abstract

The disclosure is a calibrated airflow measurement system for measuring air flow through a ceiling vent having a moveable vane. The airflow flows through the ceiling vent in laminar flow into a ceiling. This allows the moveable vane of the ceiling vent to be reversibly responsive to airflow through the room and allows for the vent to be calibrated to disperse a predetermined amount of air into the room.

Description

PRIORITY/CROSS-REFERENCE TO RELATED APPLICATIONS

This application hereby incorporates, by reference, U.S. Pat. No. 5,261,857, entitled, “Ceiling Vent with Movable Vane.”

FIELD OF THE INVENTION

This invention relates to an improvement in a ceiling vent for dispersing airflow into a room. More particularly, the invention relates to an airflow measurement system for determining outflow from a ceiling vent for adjusting the ceiling vent outflow level.

BACKGROUND OF THE INVENTION

Perhaps the most critical component of a heating or cooling system in a home or office is the vent or diffuser for dispersing the heated or cooled airflow as evenly as possible throughout the room. If diffusion of the airflow throughout the room is uneven, then pools of air of different temperatures may form at various locations in the room. This is an inefficient way to heat or cool a room and can be uncomfortable to persons who live or work there.
The best known way to diffuse airflow in a room is to redirect the airflow in a laminar flow at the top of the room. This sheet of airflow then mixes with the ambient air to achieve relatively even heating or cooling without pooling or dumping in certain locations. The distance that airflow moves at a given velocity, or airflow throw, will vary with the velocity of the airflow that moves through a vent. Thus, differences in velocity will affect the evenness of air dispersion in a room. It is highly desirable to maintain constant the airflow throw from a vent, despite variations in initial airflow velocity, to control the even mixing of airflow in a room. A fluid, such as a current of airflow that is moving at some velocity along an adjacent surface tends to cling to that surface. This is because low pressure is created below the current, in the case of a stream of airflow moving along a ceiling, thus lifting the current of airflow upward against the ceiling. This phenomenon, the Coanda effect, increases the airflow throw and thus, the dispersion of air in a room.
One proposal for maintaining even mixing of airflow from a ceiling diffuser involved a device mounted on conventional ceiling tee bars and containing a thermostatically controlled motor to position airflow control vanes to manage variable flows of conditioned air (U.S. Pat. No. 3,848,799). Another device handled variable airflow by pumping air into a bladder to regulate the area of air discharge (U.S. Pat. No. 3,434,409). Other devices of general interest had to be manually adjusted to handle different airflows (U.S. Pat. Nos. 4,475,446 and 4,008,653). These devices all suffer the disadvantages of mechanical complexity or the need for manual adjustment to handle variations in airflow.
Accordingly, applicant and co-inventors invented the device disclosed in U.S. Pat. No. 5,261,857, entitled “Ceiling Vent with Movable Vane”. The vane of that invention is normally biased toward an airflow catch which comprises a partition also positioned in the path of inflowing airflow to redirect and laterally diffuse airflow within the plenum. When there is no flow of airflow through the vent, the vane is disposed against the airflow catch to close the airflow discharge aperture. When airflow flows through the vent, the vane is moved away from the airflow catch by the force of the moving airflow to variably adjust the width of the airflow discharge aperture. Both the movable vane and the airflow catch are curved to redirect the flow of airflow in a horizontal direction as it leaves the vent. The airflow catch also circulates airflow within the plenum to disperse it toward the edges of the airflow current and homogenize the current velocities.
The problem associated with the applicant's previous invention is that, in order to calibrate the system of ceiling vents found in U.S. Pat. No. 5,261,857, a vent adjuster or a team of vent adjusters would be required to come and calibrate each of the vents individually. In order to do this, a hood is typically required to be put over each of the vents in order to calibrate the amount of air flowing out of the vent. This was relatively expensive and required time to calibrate the system. Accordingly, a system is needed that reduces the amount of time and money to calibrate the system and allows for easier calibration and recalibration of the system after the system is installed.

SUMMARY OF THE INVENTION

Accordingly, an improved ceiling vent having an airflow measurement system for dispersing airflow into a room in laminar flow with respect to the ceiling of the room has been invented. The airflow is typically within a ventilation system of a building. The ceiling vent has a vent housing configured to be mounted in a ceiling. The vent housing defines a plenum on the inside of the housing. The vent housing has at least two openings; at least one of the openings allows for air to flow into the plenum of the vent housing and at least one of the openings allows air to flow out of the airflow vent in laminar flow along the ceiling of the room in which the vent is mounted. The vent has a vane that generally has a concave curvature along its length. The vane is hingedly attached to the interior of the vent housing such that the vent moves in reaction to airflow flowing through the plenum of the vent. The vane is configured to be reversibly responsive to the airflow against the concave curvature of the vane and into the plenum. This varies the size of the opening into the room with the movement of the vane by the airflow while maintaining a curved flow path discharging the airflow in laminar flow along the ceiling. The airflow measurement system is positioned and configured such that when the vane position responds to airflow through the vent, the airflow measurement system indicates the outflow level of airflow out of the vent such that the vent can be calibrated to distribute a prescribed amount of airflow into the room. The airflow measurement system comprises a calibrated scale having airflow indicia in one embodiment. Furthermore, the calibrated scale can be located such that the vane points to one of the airflow indicia on the calibrated scale when airflow travels out of the second opening in the vent housing.
The vent can also have an airflow catch such that the airflow catch partitions airflow traveling from the inflow opening in the vent housing toward the second opening. This facilitates mixing of airflow in the plenum. Additionally, the moveable vane can be configured to be calibrated to define airflow through the plenum. The ceiling vent can also have a means for biasing the moveable vane toward the vent housing. This means for biasing the moveable vane can comprise a spring or weight attached to the movable vane that biases the vane toward the generally closed position. The second opening can comprise a wide variety of opening shapes; in one embodiment it comprises a slot in the bottom wall of the housing.
The purpose of the Abstract is to enable the public, and especially the scientists, engineers, and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection, the nature and essence of the technical disclosure of the application. The Abstract is neither intended to define the invention of the application, which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.
Still other features and advantages of the claimed invention will become readily apparent to those skilled in this art from the following detailed description describing preferred embodiments of the invention, simply by way of illustration of the best mode contemplated by carrying out my invention. As will be realized, the invention is capable of modification in various obvious respects all without departing from the invention. Accordingly, the drawings and description of the preferred embodiments are to be regarded as illustrative in nature, and not as restrictive in nature.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a ceiling vent having a movable vane, an airflow catch, and an airflow measurement system mounted in a suspended ceiling, in accordance with the present invention.

FIG. 2 shows an end elevational view of a ceiling vent having a movable vane, an airflow catch, and an airflow measurement system mounted in a suspended ceiling, in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

While the invention is susceptible of various modifications and alternative constructions, certain illustrated embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the specific form disclosed, but, on the contrary, the invention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as defined in the claims.
Referring to the drawings, FIG. 1 shows a ceiling vent 10 mounted in a suspended ceiling 12. The ceiling vent 10 is not limited to mounting in suspended ceilings, however, and may be mounted in other ceilings, such as a gypsum board ceiling 14 as in FIG. 2. The ceiling vent 10 comprises a plenum 16 and a housing 18. The housing 18 may be insulated to minimize changes in temperature of the airflow as it flows through the ceiling vent 10. In the preferred embodiment, a wall of the housing 18 has an opening 20 through which a current of heated or cooled airflow 22 a and 22 b enters the plenum 16 from an airflow and plenum source. Connected to and extending outward from the housing 18 and surrounding the opening 20 is a sleeve 24 for connecting the ceiling vent 10 to a duct that conducts heated or cooled airflow from the source.
Attached to the inside of the housing 18 is a movable vane 26 which is an elongate curved sheet that is hingedly suspended at one end of the moveable vane from the housing 18 at a hinge point 28. This vane 26 is positioned in the housing to receive the force of the inflow of airflow into the plenum 16. The bottom of the housing 18 contains a slot 30 from which airflow exits the ceiling vent 10.
Continuous with an edge of the housing 18 adjacent to the slot 30 is a curved airflow catch 32. This airflow catch 32 is a partition or sheet curving upwardly and toward the opening 20 in the housing 18. The airflow catch 32 is also positioned in the path of incoming airflow. The juxtaposition of the vane 26 and airflow catch 32 forms a flow path or passage between the vane 26 and airflow catch 32 toward the exit opening 30. Part of the airflow 22 a goes directly into this flow path, while part 22 b is diffused by circulation along the airflow catch and then into the flow path. This redistributes airflow to the edges for unifying the current velocities.
The hinge point 28 of the movable vane 26 is positioned so that gravity normally biases the vane 26 toward the airflow catch 32. Other methods of biasing the vane 26 toward the airflow catch 32 are by springs or weights which impose a comparable biasing load to that of gravity. If no airflow is flowing through the ceiling vent 10, then the vane 26 is in a closed position 34 in contact with the airflow catch 32. When airflow moves into the vent 10 from a source, the force of moving airflow moves the vane 26 away from the airflow catch 32. Depending on the velocity of the airflow, the vane 26 will move to a fully open position 36 or to any intermediate position 38 between fully open 36 and closed 34. The curved shape of the vane 26 redirects airflow as it flows through the vent 10 for laminar flow along the ceiling.
The distance between the bottom edge of the movable vane 26 and the curved surface of the airflow catch 32 defines an opening 40 of variable width through which airflow exits the vent 10 to the room. The width of the opening 40, as determined by the extent of deflection of the curved vane 26 in response to the force of inflowing airflow, regulates the velocity of outflowing airflow. Not only is the velocity of outflowing airflow regulated by the vent 10, but the outflowing airflow is directed by the interaction of the concave side of vane 26 and convex side of airflow catch 32 in a laminar flow along the ceiling of the room. As noted in the figures, the concavity of the vane 26 and the convexity of the airflow catch 32 are continuous along the passage sides of the respective vane and catch and up to the opening 40.
The airflow catch 32 diffuses and disperses the current of airflow that enters the ceiling vent 10, especially the airflow that enters at lower levels in the current, such as at 22 b. The airflow catch 32 splits this airflow off and circulates it within the plenum and disperses it laterally, as depicted by dashed line 22 b. The curved configuration of the airflow catch 32 generates a circular flow path within a forward portion 35 of the plenum, and then upward to the primary flow path 22 a. The airflow that is thus circulated by the airflow catch 32 rejoins the upper level current of airflow 22 a, is redirected by the movable vane 26, and exits the vent in a generally horizontal direction along the top of the room. The airflow catch 32, by dispersing airflow laterally within the vent 10 makes the velocity of outflowing airflow constant across the cross section of outflowing airflow instead of faster at the center of the outflow than at the edges. Further, airflow flow rates are increased by this homogenization of outflowing air.
In the embodiment of FIG. 1 the airflow measurement system comprises a calibrated scale 54 attached to the end plate of the vent housing such that when the vane 36 moves in response to airflow through the plenum of the vent and out the second opening the tip 56 of the vane indicates on the calibrated scale the amount of air that is flowing out the bottom of the vent. The system can subsequently be calibrated to distribute a predetermined amount of airflow into a room. For example, one method of accomplishing this would be to adjust the hinge 28 to stop at a certain set point at which a prescribed amount of airflow would enter the room. The airflow measurement system 54 can comprise a wide variety of systems that are known in the art. Airflow measurement systems generally include the illustrated calibrated scale attached to the vent housing, a similar calibrated scale attached to the vane such that, when the vane moves in response to airflow, a separate stationary pointer points to the airflow level on the calibrated scale, or any variety of digital or mechanical airflow measurement systems.
FIG. 2, illustrates the vent 10 comprises a housing 18 that defines a chamber 16 through which airflow may pass from the plenum source into the room. FIG. 2 illustrates an embodiment of the airflow measurement system 54 comprising a calibrated scale attached to the vent housing. The airflow measurement system can be attached in a wide variety of positions on the vent housing including on the airflow catch 32, the moveable vane 36, the endplate of the vent housing 56, or any location where it functions to measure airflow out of the ceiling vent.
The housing 18 contains an inlet opening 20 for supplying airflow to the chamber 16. Coupled to the inlet opening 20 are means 24 for attaching a conduit connecting the vent 10 to the plenum source. In the preferred embodiment, these means are a sleeve 24. Hingedly attached to the housing 18 within the chamber 16 is a vane 26 which may rotate about a rotational axis 28 and is positioned in the intended flow path of airflow 22 a and 22 b entering the chamber 16 through the inlet opening 20. The vane 26 exerts a deflecting resistance against the entering airflow 22 a and 22 b which causes rotation of the vane 26 to a variable degree in response to the velocity of the entering airflow 22 a and 22 b. The vent 10 also comprises an outlet opening 30 within the housing 18. This outlet opening 30 is positioned to receive airflow from the vane 26 and its opening size varies with the degree of rotation of the vane 26 in response to changing velocities of the entering airflow 22 a and 22 b. The outlet opening 30 is sufficiently small to provide a change in velocity to airflow as it exits the outlet opening 30. The invention also comprises means 32 associated with the vane 26 and outlet opening 30 for directing airflow and causing initial laminar flow of airflow exiting the outlet opening 30. In the preferred embodiment, these directing means 32 define an airflow catch 32.
To illustrate how this ceiling vent 10 tends to maintain constant the airflow throw of airflow currents of varying velocities, comparison with a vent of fixed aperture is useful. High-velocity airflow moving through an aperture of fixed width will accelerate as it travels through the aperture. Thus, not only does the airflow enter the vent at high velocity, but it is accelerated as it exits. Low-velocity airflow moving through the same aperture may accelerate as it moves through the aperture as well, but the acceleration will be less than that of the high-velocity airflow. Thus, the difference in velocities of the high-velocity airflow and low-velocity airflow is increased after moving through the fixed aperture.
In contrast, the difference in velocity of high-velocity airflow and low-velocity airflow decreases after moving through a variable aperture that is responsive to the flow rate of airflow. Acceleration of the high-velocity airflow through the variable aperture will be less than it would have been through a fixed aperture because the aperture will widen in response to the force exerted by the high-velocity airflow against the movable vane 26. A limiting flange 37 blocks further movement rearward and sets the maximum size of the outlet. Also, acceleration of the low-velocity velocity airflow through the variable aperture will be more than it would have been through a fixed aperture because the aperture will narrow in response to the lower force exerted by the low-velocity velocity airflow against the movable vane 26. Thus, a ceiling vent 10 with a movable vane 26 to vary the aperture through which airflow exits to the room, tends to maintain a more constant velocity of exiting airflow and, hence, a more constant airflow flow throw.
While there is shown and described the present preferred embodiment of the invention, it is to be distinctly understood that this invention is not limited thereto, but may be variously embodied to practice within the scope of the following claims. From the foregoing description, it will be apparent that various changes may be made without departing from the spirit and scope of the invention as defined by the following claims. For example, although the disclosure refers to the vane being in a generally closed position when airflow is not flowing through the vane, the generally closed first position is the ideal position for the vane to be in when no airflow is flowing through the system. The first position is not required to be completely closed and is the relative description of the vane in the position without airflow flowing through the vent housing.

Claims

1. An improved ceiling vent for dispersing airflow from an airflow generated by a ventilation system into a room in laminar flow with respect to a ceiling of said room, wherein said vent comprises:

a vent housing configured to be mounted in a ceiling, wherein said vent housing comprises a top, a bottom, a first side, a second side, a third side, and a forth side, wherein said first side and said second side are generally opposite, wherein said third side and said fourth side are generally opposite, wherein said vent housing defines a plenum on an interior of said housing, wherein said vent housing comprises at least two openings, wherein said openings comprise at least one first opening in at least one of said first side, said second side, said third side, or said fourth side of said vent housing for permitting inflow of said airflow from said ventilation system into said plenum, wherein said openings comprise at least one second opening in said bottom side of said vent housing for permitting said airflow to flow from said plenum into said room;

a vane comprising a concave curvature along its length, wherein said vane comprises a first end and a second end, wherein said first end of said vane is hingedly attached to said interior of said vent housing to form a movable side of said second opening for adjustment of said width of said opening and being positioned to receive inflow of airflow into said plenum, wherein said vane is configured and positioned such that when said ventilation system is not generating airflow said vane is biased to generally close said second opening, wherein said vane is configured such that when airflow is flowing from said first opening toward said second opening said airflow moves said vane such that said airflow flows from said first opening through said second opening, wherein said vane is configured to regulate said amount of airflow from said first opening through said second opening such that said position of said vane is reversibly responsive to said airflow against said concave curvature of said vane and into said plenum to vary said size of said second opening with movement of said vane by said airflow while maintaining a curved flow path which discharges said airflow in laminar flow along said ceiling, wherein said vane stabilizes a velocity of airflow that flows out from said plenum through said second opening into said room, wherein said vane is configured to be calibrated to distribute a predetermined amount of airflow into said room; and

wherein said improvement comprises an airflow measurement system attached to said ceiling vent, wherein said airflow measurement system is positioned and configured such that when said vane position responds to said airflow, said airflow measurement system indicates said outflow level of airflow out of said vent such that said ceiling vent can be calibrated to distribute a prescribed amount of airflow into said room.

2. The ceiling vent of claim 1 wherein said airflow measurement system comprises a calibrated scale comprising airflow measurement indicia, wherein said calibrated scale is positioned and configured such that when airflow flows through said ceiling vent, said calibrated scale indicates said amount of said outflow of airflow out of said second opening.

3. The ceiling vent of claim 2 wherein said calibrated scale is positioned such that when said airflow moves said vane and flows through said second opening, said vane points to one of said airflow indicia on said calibrated scale to indicate said airflow out of said second opening.

4. The ceiling vent of claim 1 wherein said ceiling vent comprises an airflow catch attached to said housing, wherein said airflow catch comprises a generally circular sheet continuous with an edge of said vent housing at said second opening, wherein said airflow catch is configured and positioned to partition said airflow from said first opening to said second opening to facilitate mixing of said airflow flowing into said plenum.

5. The ceiling vent according to claim 4 wherein said airflow catch is in a generally curved shape and configured to generate a circular flow path of airflow within said plenum to facilitate mixing of airflow flowing into said plenum.

6. The ceiling vent according to claim 4 wherein said airflow catch comprises an extension of said vent housing.

7. The ceiling vent according to claim 1 further comprising means for biasing said movable vane toward said generally closed position such that said vane is configured to be calibrated such that when airflow is flowing through said ceiling vent, said vane can be calibrated to define said amount of airflow flowing out of said second opening.

8. The ceiling vent according to claim 7 wherein said means for biasing said movable vane toward said vent housing comprises a spring or a weight attached to said movable vane and configured for biasing said movable vane toward said generally closed position.

10. The ceiling vent according to claim 1 wherein said second opening comprises a slot in said bottom wall of said vent housing.

11. The ceiling vent according to claim 1 wherein said movable vane forms one side of a narrowing passage having a concave curvature extending to said second opening for directing said outflow of airflow from said vent in laminar flow along said ceiling of said room to stabilize airflow throw said ceiling vent.

12. The ceiling vent according to claim 10 wherein said airflow catch comprises an edge of said bottom wall and an edge of said slot, wherein said airflow catch curves generally upward and toward said first opening, wherein said airflow catch forms a generally circular structure such that said airflow catch and said movable vane are configured to form a generally circular airflow path through at least a portion of said ceiling vent when said airflow is flowing through said ceiling vent.

13. The ceiling vent according to claim 1, wherein said airflow measurement system is attached to at least one of said movable vane or said vent housing.

14. An improved ceiling vent for dispersing airflow from an airflow generated by a ventilation system into a room in laminar flow with respect to a ceiling of said room, wherein said vent comprises:

a vane comprising a concave curvature along its length, wherein said vane comprises a first end and a second end, wherein said first end of said vane is hingedly attached to said interior of said vent housing to form a movable side of said second opening for adjustment of said width of said opening and being positioned to receive inflow of airflow into said plenum, wherein said vane is configured and positioned such that when said ventilation system is not generating airflow said vane is biased to generally close said second opening, wherein said vane is configured such that when airflow is flowing from said first opening toward said second opening, said airflow moves said vane such that said airflow flows from said first opening through said second opening, wherein said vane is configured to regulate said amount of airflow from said first opening through said second opening such that said position of said vane is reversibly responsive to said airflow against said concave curvature of said vane and into said plenum to vary said size of said second opening with movement of said vane by said airflow while maintaining a curved flow path which discharges said airflow in laminar flow along said ceiling, wherein said vane stabilizes a velocity of airflow that flows out from said plenum through said second opening into said room, wherein said vane is configured to be calibrated to distribute a predetermined amount of airflow into said room;

an airflow catch attached to said housing, wherein said airflow catch comprises a generally circular sheet continuous with an edge of said vent housing at said second opening, wherein said airflow catch is configured and positioned to partition said airflow from said first opening to said second opening to facilitate mixing of said airflow flowing into said plenum; wherein said airflow catch and said movable vein are configured to form a generally circular airflow path of air flowing from said first opening through said vent housing; and

15. The ceiling vent of claim 14 wherein said airflow measurement system comprises a calibrated scale comprising airflow measurement indicia, wherein said calibrated scale is positioned and configured such that when airflow flows through said ceiling vent, said calibrated scale indicates said amount of said outflow of airflow out of said second opening.

16. The ceiling vent of claim 15 wherein said calibrated scale is positioned such that when said airflow moves said vane and flows through said second opening, said vane points to one of said airflow indicia on said calibrated scale to indicate said airflow out of said second opening.

17. The ceiling vent according to claim 14, wherein said airflow measurement system is attached to at least one of said movable vane, said vent housing, or said air catch.

18. The improved ceiling vent according to claim 14 further comprising means for biasing said movable vane toward said generally closed position such that said vane is configured to be calibrated such that when airflow is flowing through said ceiling vent, said vane can be calibrated to define said amount of airflow flowing out of said second opening.

19. An improved ceiling vent for dispersing airflow from an airflow generated by a ventilation system into a room in laminar flow with respect to a ceiling of said room, wherein said ceiling vent comprises:

a vent housing configured to be mounted in a ceiling, wherein said vent housing defines a plenum on said interior of said housing, wherein said vent housing comprises at least one first opening for permitting inflow of airflow from said ventilation system into said plenum, wherein said vent housing comprises at least one second opening for permitting outflow of airflow from said plenum into said room; and

an airflow catch attached to said housing, wherein said airflow catch comprises a generally concave curvature continuous with an edge of said vent housing at said second opening such that said airflow catch is positioned and configured to diffuse a part of said inflow of airflow from said first opening; and

a vane comprising a concave curvature along its length, wherein said vane comprises a first end and a second end, wherein said vane is hingedly attached to said interior of said vent housing to form a movable side of said second opening for adjustment of said width of said opening and being positioned to receive said force of said inflow of airflow into said plenum, wherein said vane is configured and positioned such that when said ventilation system is not generating airflow said vane is biased to close said second opening, wherein said vane is configured such that when airflow is flowing from said first opening toward said second opening said airflow moves said vane such that said airflow flows from said first opening to said second opening, wherein said vane is configured to regulate said amount of airflow from said first opening through said second opening such that said position of said vane is reversibly responsive to said force of said inflow of airflow against said concave curvature of said vane and into said plenum to vary said size of said second opening with movement of said vane by said force while maintaining a curved flow path which discharges in laminar flow along said ceiling, wherein said vane stabilizes a velocity of airflow that flows out from said plenum through said second opening into said room, wherein said vane is configured to be calibrated to distribute a predetermined amount of airflow into said room; and

a means for biasing said movable vane toward said generally closed position such that said vane is configured to be calibrated such that when airflow is flowing through said ceiling vent, said vane can be calibrated to define said amount of airflow flowing out of said second opening; and

wherein said improvement comprises an airflow measurement system attached to said ceiling vent and positioned and configured such that when said vane position responds to said force of said inflow of airflow, said airflow measurement system indicates said outflow level of airflow out of said vent such that said ceiling vent can be calibrated to distribute a prescribed amount of airflow into said room, wherein said airflow measurement system comprises a calibrated scale comprising airflow measurement indicia, wherein said calibrated scale is positioned and configured such that when airflow flows through said ceiling vent, said calibrated scale indicates said amount of said outflow of airflow out of said second opening by pointing generally to one of said indicia on said calibrated scale.

20. The improved ceiling vent of claim 19 wherein said means for biasing said movable vane toward said vent housing comprises a spring or a weight attached to said movable vane and configured for biasing said movable vane toward said generally closed position.