Patent Publication Number: US-9423143-B2

Title: HVAC actuator with light indicator

Description:
TECHNICAL FIELD 
     The disclosure relates generally to actuators, and more particularly, to HVAC actuators for use in HVAC systems. 
     BACKGROUND 
     Heating, ventilation and/or air conditioning (HVAC) systems are often used to control the comfort level within a building or other structure. Such HVAC systems typically include an HVAC controller that controls various HVAC components of the HVAC system in order to affect and/or control one or more environmental conditions within the building. The HVAC components may include, for example, a furnace, an air conditioner, and associated ductwork, such as in a forced air system, and/or a boiler, radiators, and associated plumbing, such as in a hydronic heating system, as well as many other possible components and configurations. 
     In forced air systems, the conditioned air is typically provided by a furnace and/or air conditioner through a plenum to a network of supply air ducts that distribute the conditioned air throughout the building. A network of return air ducts is often used to return air from the building back to the furnace and/or air conditioner. A blower is used to draw the return air through the return air ducts, and drive the return air through the furnace and/or air conditioner and into the supply air ducts via the plenum. In some cases, some of the air is replaced over time with fresh outside air, often through an energy recovery ventilator or the like. Airflow in a force air system may be controlled in part through the use of one or more dampers. 
     In a zoned system, conditioned air is delivered to each zone based on the heat load in that zone. Dampers are typically placed in the supply air ducts that feed each zone. By activating damper actuators, the conditioned air may be delivered to only those zones that are calling for conditioned air. In some cases, a bypass damper may be placed in a bypass duct that extends between the supply duct (or the plenum) and the return air duct. This may allow some of the supply air to pass directly to the return air duct when the pressure in the plenum rises above a threshold value, such as when only a small number of zones are calling for conditioned air. A ventilator may also be controlled by one or more dampers. In each of these cases (zoning, bypass, ventilation) and others, a damper actuator may be used to provide automatic control of a damper. HVAC actuators are also employed in other contexts as well. For example, a hydronic heating or cooling system may employ HVAC actuators to control valves that govern the flow of fluids in the system. 
     SUMMARY 
     The disclosure relates generally to actuators, and more particularly, to HVAC actuators for use in HVAC systems. In one example, an HVAC actuator may include an output shaft rotatable between a first end position and a second end position, a drive mechanism configured to selectively drive the output shaft toward the first end position, and a housing substantially enclosing the drive mechanism. The HVAC actuator may further include a first light source disposed within the housing configured to provide first light having a first color. The housing may include a first window positioned to provide visibility of the first light from the first light source to an observer external the housing. An aperture member may be situated between the first light source and the first window of the housing with the aperture member configured to move as the output shaft is rotated. The aperture member may have two or more spaced openings that transmit the first light to the first window at each of two or more positions of the output shaft. The aperture member may be configured to rotate or otherwise move as the output shaft is rotated. In some examples, the two or more openings of the aperture member are configured to cause the appearance of blinking of the first light through the first window as the output shaft is rotated toward the first end position. One of the openings may be configured to be in registration with the first light source at the first end position. 
     In some instances, the aperture member may includes a position indicator marking, and the housing may include a position indicator window through which the position indicator marking is visible from external the housing between the first end position and the second end position of the output shaft. 
     In some instances, the HVAC actuator may include a range stop adjustment mechanism that allows an operator to select a first stop position from a plurality of discrete first stop positions, and each of two or more of the openings of the aperture member may be configured to be in registration with the first light source at corresponding ones of the discrete first stop positions. The discrete first stop positions may be discrete positions where rotation of the output shaft is stopped as it rotates toward, but before it reaches, the first end position. 
     In another example, an HVAC actuator may include an output shaft rotatable between a first end position and a second end position, a drive mechanism configured to selectively drive the output shaft toward the first end position, and a housing. The HVAC actuator may include a first light source disposed within the housing configured to provide first light having a first color, and a second light source, disposed within the housing and spaced from the first light source, configured to provide second light having a second color. The housing may include a first window positioned to provide visibility of the first light from the first light source to an observer external the housing and a second window spaced from the first window and positioned to provide visibility of the second light from the second light source to an observer external the housing. An aperture wheel may be situated between the first light source and the first window and between the second light source and the second window. The aperture wheel may be configured to rotate as the output shaft is rotated. The aperture wheel may have two or more spaced openings that transmit the first light to the first window at each of two or more first positions of the output shaft and transmit the second light to the second window at each of two or more second positions of the output shaft. 
     In some instances, one of the openings of the aperture wheel is configured to be in registration with the first light source at the first end position, and none of the openings are in registration with the first light source when the output shaft is at the second end position, and further, one of the openings is configured to be in registration with the second light source at the second end position, and none of the openings are in registration with the second light source when the output shaft is at the first end position. In some cases, either or both of the first end position and the second end position are adjustable. 
     In another example, a method for operating an HVAC actuator may include rotating an output shaft toward a first end position, moving an aperture member as the output shaft is rotated toward the first end position, and stopping rotation of the output shaft when the output shaft reaches the first end position. The aperture member may have two or more spaced openings that transmit a first light from a first light source to a first window of a housing at each of two or more positions of the output shaft. The two or more openings of the aperture member may be configured to cause the appearance of blinking of the first light through the first window as the output shaft is rotated toward the first end position and remaining lit when the output shaft is at the first end position. 
     In some instances, the method may further include rotating the output shaft toward a second end position, moving the aperture member as the output shaft is rotated toward the second end position, and stopping rotation of the output shaft when the output shaft reaches the second end position. The two or more spaced openings of the aperture member may be configured to transmit a second light from a second light source to a second window of the housing at each of two or more positions of the output shaft, with the two or more openings of the aperture member being configured to cause the appearance of blinking of the second light through the second window as the output shaft is rotated toward the second end position and remaining lit when the output shaft is at the second end position. 
     The above summary is not intended to describe each and every example or every implementation of the disclosure. The Description that follows more particularly exemplifies various illustrative embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The following description should be read with reference to the drawings. The drawings, which are not necessarily to scale, depict several examples and are not intended to limit the scope of the disclosure. The disclosure may be more completely understood in consideration of the following description with respect to various examples in connection with the accompanying drawings, in which: 
         FIG. 1  is a schematic perspective view of a portion of a duct with a damper assembly driven by an illustrative HVAC actuator; 
         FIG. 2  is a schematic side view of the duct, damper assembly and illustrative HVAC actuator of  FIG. 1 ; 
         FIG. 3  is a schematic perspective view of a front side of the illustrative HVAC actuator of  FIG. 1 ; 
         FIG. 4  is a schematic perspective view of a back side of the illustrative HVAC actuator of  FIG. 1 ; 
         FIG. 5  is a schematic perspective view of illustrative HVAC actuator from the same viewpoint as  FIG. 4 , but with the housing and plate removed, showing further details of the range adjustment lever and the operation of the range adjustment mechanism; 
         FIG. 6  is a schematic perspective view of the illustrative HVAC actuator of  FIG. 1  showing a faceplate on the front side; 
         FIG. 7  is a schematic perspective view of the illustrative HVAC actuator of  FIG. 6  with the faceplate removed; 
         FIG. 8  is a schematic perspective view of the illustrative HVAC actuator of  FIG. 7  with the housing also removed; 
         FIG. 9  is a schematic perspective view of the illustrative HVAC actuator of  FIG. 8  with the aperture wheel also removed; 
         FIGS. 10A-E  are schematic perspective front views of the illustrative HVAC actuator showing the aperture wheel disposed at different orientations relative to the light sources; 
         FIG. 11A  is a schematic cross sectional side view of an illustrative faceplate, aperture member/wheel, and circuit board having a first light source and a second light source; 
         FIG. 11B  is a schematic cross sectional view of another illustrative faceplate, aperture member/wheel, and circuit board having a first light source; 
         FIG. 12  is a schematic illustration of a faceplate of another illustrative HVAC actuator similar to the HVAC actuator of  FIG. 1 ; 
         FIG. 13  is a schematic illustration of another illustrative example of an aperture member; 
         FIG. 14  is a schematic perspective view of the illustrative HVAC actuator of  FIG. 1  showing details of a terminal block having a removable blocking tab; and 
         FIG. 15  is a schematic partial exploded view of the illustrative HVAC actuator of  FIG. 1 . 
     
    
    
     DESCRIPTION 
     The following description should be read with reference to the drawings, in which like elements in different drawings are numbered in like fashion. The drawings, which are not necessarily to scale, depict selected examples and are not intended to limit the scope of the disclosure. Although examples of construction, dimensions, and materials are illustrated for the various elements, those skilled in the art will recognize that many of the examples provided have suitable alternatives that may be utilized. 
     HVAC systems may employ actuators for a variety of purposes, including, for example, the control of dampers in forced air systems. HVAC dampers may be employed in a number of applications, with each application having its own specific requirements that may differ from the requirements of other applications. For example, zoning dampers may be “normally open,” meaning that the flow of air in the duct is generally not restricted by the damper unless the damper has specifically been commanded to be closed. In contrast, ventilation or bypass dampers may be “normally closed,” generally preventing the flow of air unless commanded open. Normally open and normally closed dampers may be configured to revert to their normal (open or closed) state in the event of a loss of power and/or command signal. In some cases, a damper may include a spring or other bias mechanism that is configured to return to the damper to the normal (open or closed) state. In other cases, a damper may be powered in both directions by a motor or the like. 
     While some dampers may be controlled between a fully open and a fully closed state, in some applications it may be desirable for the damper to be controllable between, for example, an open state and a state that is not completely closed. This may help, for example, to maintain a minimum airflow to a zone of a building. Similarly, it may be desirable to prevent a damper from opening completely to help limit airflow to a zone of a building. In such cases, it may be desirable to establish a range stop to prevent the damper from fully closing or fully opening, depending on the application. 
     The variety of use scenarios for actuated dampers in HVAC systems often requires a technician&#39;s diligence in considering and properly accounting for the particular requirements of the damper and damper actuator being installed or maintained. The present disclosure provides improved damper actuators with features that make their installation and maintenance easier. Such features include, but are not limited to, visual indicators that indicate the position and/or status of the actuator, adjustment mechanisms that are easy to access and use, and structures that help guide aspects of installation. 
     While the present disclosure largely describes HVAC actuators in the application of damper actuators, it is contemplated that features described herein have utility for other applications, such as HVAC actuators for valves and the like. Furthermore, it is contemplated that various features of HVAC actuators of the present disclosure may be combined in any compatible combination, and that the present disclosure should not be considered to be limited to only the specific combinations of features explicitly illustrated. 
       FIG. 1  is a schematic perspective view of a portion of a duct  30  with a damper assembly driven by an illustrative HVAC actuator  100 . The damper components other than the HVAC actuator  100  may be referred to collectively as an HVAC component, to which the HVAC actuator may be coupled. The damper assembly may include a damper blade  52  rotatably mounted on a damper shaft  54  between a closed state or position (illustrated) and an open state or position. In the fully closed state, damper blade  52  may be disposed in close contact with one or more damper stops  56  attached to the duct  30 , with the damper blade and damper stops substantially closing the duct to the flow of air. In the schematic arrangement illustrated in  FIG. 1 , the plane of the damper blade  52  is substantially perpendicular to the longitudinal axis of duct  30  when the damper is fully closed, however, this is not necessary, and a damper assembly may be configured with a damper blade and damper stops structured to substantially close the duct with the damper blade at a different angle relative to the duct. In the fully open state, generally the plane of the damper blade  52  will be parallel with the airflow in the duct  30 , which generally would be the case with the plane of the damper blade being parallel to the longitudinal axis of the duct. 
       FIG. 2  is a schematic side view of duct  30 , damper assembly and illustrative HVAC actuator  100  of  FIG. 1 . Damper shaft  54 , which may also be referred to as an input shaft, may extend out of the duct wall through an aperture in the duct wall. The illustrative HVAC actuator  100  includes a rotatable output shaft  102  that may be operatively coupled to the end of damper shaft  54  as illustrated in  FIG. 2 , such that rotational torque effective to rotate the damper shaft  54  and damper blade  52  may be imparted by the output shaft  102 . In the example shown, a set screw  104  may be employed as a coupling mechanism for securing the output shaft  102  of the illustrative HVAC actuator to the damper shaft  54 , but this is not limiting and other suitable coupling mechanism may be employed as desired. Output shaft  102  may have a full range of rotation between a first end position and a second end position, which may correspond to the fully closed and fully open states of the damper (or vice-versa). HVAC actuator  100  may include a drive mechanism (not visible in  FIG. 1 or 2 ) configured to selectively drive the output shaft  102 . The drive mechanism of HVAC actuator  100  may be housed entirely or in part within a housing  106 . Housing  106  may have a front side (e.g., the side toward the top of FIG.  2 ) that faces away from the duct  30  and damper components, and a back side (e.g., the side toward the bottom of  FIG. 2 ) that faces toward the duct and damper components when the HVAC actuator is operatively coupled to the duct and damper components. In some instances, the back wall of the housing  106  may be held away from the outer wall of the duct wall by a gap by virtue of the output shaft  102  extending out from the back side of the housing  106  and being mounted to the end of the damper shaft  54  as shown. 
     When output shaft  102  of HVAC actuator  100  rotates relative to housing  106 , it may rotate damper shaft  54  and in turn damper blade  52  relative to duct  30 , provided that the housing  106  does not move relative to the duct. To help prevent such movement, an anti-rotation rod  108  may be attached to housing  106 , and the rod  108  may be inserted into a hole in the duct wall of duct  30 . This is one implementation, and it is contemplated that any suitable anti-rotation mechanisms may be used, as desired. Anti-rotation rod  108  may be referred to as a stop. As illustrated, the back wall of the housing  106  may be configured to be spaced from the outer surface of the duct  30 , and the anti-rotation rod or stop  108  may be configured to extend out away from the back wall of the housing  106  towards the duct to engage the duct wall when the HVAC actuator  100  is coupled to the damper components. 
     HVAC actuators of the present disclosure may include further features to ease their installation and maintenance. HVAC ducts are often insulated to retard heat loss and/or gain to/from the environment. Insulation may take the form of an insulating layer around the outer surface  32  of the duct. Referring back to  FIG. 2 , an outer surface  34  of an insulating layer  36  around duct  30  is represented in phantom outline. Where HVAC actuator  100  is disposed when coupled to the duct  30  and damper components, there may be a discontinuity in the insulating layer  36 . To reduce insulative losses at the HVAC actuator  100 , technicians may apply tape between the insulating layer  36  and the HVAC actuator  100 . To facilitate such taping, HVAC actuator  100  may include a taping flange  210 . Taping flange  210  may be configured to extend transversely away from the housing  106  and provide a taping surface  212  facing away from the duct  30 . The taping flange  210  may further be configured to be spaced from the outer surface  32  of the duct  30  and adjacent to the outer surface  34  of the insulating layer  36  of the duct when the HVAC actuator  100  is coupled to the damper components. In some other illustrative examples, an HVAC actuator is coupled to a valve, which may be disposed in a pipe or other fluid handling enclosure to which insulation may applied similarly as with duct  30  of  FIG. 2 . 
     Taping flange  210  may be configured to facilitate taping of the HVAC actuator  100  to the outer surface  34  of the insulating layer  36 . The taping flange  210  may be shaped to provide a front-facing surface  212  that is suitable for receiving tape to provide a seal between the taping flange  210  and the outer surface  34  of the insulating layer  36 . The taping flange  210  may extend outward from the housing  106  around the entire perimeter of the housing, as illustrated. It may extend outward from the housing  106  by at least a minimum distance around the entire perimeter of the housing, for example, by at least 3 mm, 5 mm, 10 mm, or any other suitable distance. The taping flange  210  may extend outward from the housing  106  approximately perpendicular to adjacent side walls of the housing, but this is not required. 
     The taping flange  210  may be disposed relative to the other parts of the HVAC actuator at any suitable location. The front-facing surface  212  of the flange  210  may be disposed between the front side and back side of the housing  106 . In some cases, the flange  210  may be disposed substantially in registration with the back side of the housing  106 . 
     The taping flange  210  may be formed in any suitable way. The taping flange  210  may be formed integrally with the housing  106 . In other illustrative embodiments, the taping flange  210  may be formed separately from the housing  106  and coupled to the housing. 
     The present disclosure contemplates a method for installing an HVAC actuator such as HVAC actuator  100  for driving an HVAC damper that is disposed in an insulated duct. The method may include the steps of operatively coupling an output shaft of the HVAC actuator to the input shaft of the HVAC damper and providing tape between a taping flange of the HVAC actuator and the outer surface of the insulating layer of the duct to form a seal. The method may further include the step of inserting a stop of the HVAC actuator through an aperture in the duct wall before operatively coupling the output shaft of the HVAC actuator to the input shaft of the HVAC damper. The method may also include tucking at least part of the insulating layer under the taping flange before providing tape between the taping flange of the HVAC actuator and the outer surface of the insulating layer of the duct to form a seal. 
     As mentioned elsewhere herein, in some situations it may be desired to control the state of a damper to other than fully-open and/or fully-closed states. HVAC actuators of the present disclosure may be configured with a range adjustment mechanism to allow adjustment of their ranges of motion. For example, the illustrative damper system of  FIG. 1  is illustrated with damper blade  52  and damper shaft  54  rotated to a fully closed position, with damper blade  52  in contact with damper stop  56 . In a fully open position, damper blade  52  and damper shaft  54  may be rotated about 90 degrees clockwise, as viewed from the side of HVAC actuator  100 , which we may refer to as the top side (relative to the drawing, but not necessarily describing a real-world spatial orientation of such a system). When fully open, the damper blade  52  and damper shaft  54  may be described (arbitrarily) as being disposed at 0 degrees, and when fully closed, at 90 degrees. Note that not all damper systems necessarily rotate through a range of 90 degrees between fully open and fully closed, and the description in the present disclosure of such a system should not be considered limiting. In applications where it may be desired to provide partially-closed states, an HVAC actuator may incorporate a range adjustment mechanism that prevent the actuator from rotating the damper blade  52  and damper shaft  54  (via output shaft  102 ) to the 90 degree fully closed position.  FIGS. 3-5  illustrate aspects of an illustrative range adjustment mechanism. Similarly, in some illustrative examples, a range adjustment mechanism may be configured to prevent an actuator from rotating a damper blade and shaft to a 0 degree fully open position. 
       FIG. 3  is a schematic perspective view of a front side of the illustrative HVAC actuator  100  showing, among other features, a range adjustment knob  110 . The range adjustment knob  110  is part of a range adjustment lever  111  more fully viewable in  FIGS. 4, 5 , and other Figures of this disclosure. In the example shown, range adjustment knob  110  is disposed on front side of housing  106 , where it may be manipulated easily by a user after the HVAC actuator  100  is mounted to a damper shaft  54  to allow the user to selectively limit rotation of the output shaft to a reduced range that is a subset of the full range of motion of the output shaft. An indicator  112  on housing  106  may indicate, in conjunction with the position of range adjustment knob  110 , the adjustment of the range that has been selected, if any. As illustrated, indicator  112  may include indicia labeled “0”, “1”, “2”, and “3”, although this is not limiting, and the indicator may include fewer or more indicia in some examples. 
     The indicia “0”, “1”, “2”, and “3” may indicate discrete locations at which the range adjustment lever  111  and knob  110  may be set and adjusted between. Setting the range adjustment lever  111  and knob  110  to one of the discrete locations such as “0”, “1”, “2”, and “3” may allow a user to select a predetermined reduced range of motion that is a subset of the full range of motion of the output shaft  102 . Depending on the number of discrete locations provided, the range adjustment lever  111  may allow the user to select between no reduced range and a single predetermined reduced range, or a greater number of predetermined reduced ranges, such as two, three, or more. In the illustrative example of  FIGS. 3-5 , three predetermined reduced ranges (“1”, “2”, and “3”) are provided. Indicator  112  may also be referred to as a range indicator, and/or indicia “0”, “1”, “2”, and “3” may be referred to as range indicators, in that they may indicate, in conjunction with the range adjustment knob  110  of the range adjustment lever  111 , which range or predetermined reduced range is selected. 
     Indicium “0” may indicate a no stop position or setting of the range adjustment mechanism, in which the output shaft  102  is not restricted from rotating around its full range of motion completely from first end position (e.g., fully closed, 90 degrees) to second end position (e.g., fully open, 0 degrees). Indicia “1”, “2”, and “3” may indicate positions or settings of the range adjustment mechanism in which the output shaft  102  is restricted from rotating around its full range of motion in progressively smaller reduced ranges. For example, when set to position “1”, the range may be restricted between 80 degrees (10 degrees from fully closed) and 0 degrees (fully open), when set to position “2”, the range may be restricted between 65 degrees and 0 degrees, and when set to position “3”, the range may be restricted between 50 degrees and 0 degrees, although these values of 80, 65, and 50 degrees are merely exemplary and should not be considered limiting. In the example of this paragraph, the predetermined reduced ranges “1”, “2”, and “3” each includes the second end position (0 degrees) but has different first stop position (80, 65, and 50 degrees), the different first stop positions corresponding to partially-closed damper states. In other illustrative examples, predetermined reduced ranges may have a common first end position but different second stop positions. In some instances, and while not explicitly shown in  FIG. 3 , there may be two adjustment levers provided; one for controlling one end (e.g. more closed end) of the desired range of motion and another for controlling the other end (e.g. more open end) of the desired range. 
       FIG. 4  is a schematic perspective view of illustrative HVAC actuator  100  showing features visible on the back side of the actuator, including the range adjustment lever  111 . The range adjustment lever  111  may be rotatably mounted concentric with the output shaft  102  of the HVAC actuator  100 . The range adjustment lever  111  may have a first portion  114  extending radially outward relative to the output shaft  102  and a second portion  116  that extend from the first portion toward the front side of the housing  106 . The range adjustment knob  110  may be considered to be a part of the second portion  116 , or it may be considered to be attached to the second portion. The housing  106  may include an opening  118  through which the second portion  116  extends from the back side to the front side of the housing  106 , although this is not necessary. In some illustrative examples, a range adjustment lever may extend from back to front around the outside of the housing. In some illustrative examples, a range adjustment lever may not extend from the back to the front of an actuator entirely, or at all. In some such cases the range adjustment lever may be manipulatable from the front side of the housing, for example, by extending a tool or a finger through an opening in the housing to reach the range adjustment lever for adjustment. 
     As shown, the illustrative HVAC actuator  100  includes a plate  120  that is generally perpendicular to the output shaft  102  and proximal the first portion  114  of the range adjustment lever  111 . The plate  120  may be rigidly affixed relative to the housing  106 . The plate  120  may form at least part of a back surface of the housing  106  of the HVAC actuator  100 , but this is not required. In some illustrative examples, the plate  120  may be disposed at an intermediate depth within the interior of the HVAC actuator housing. In the example shown, plate  120  may include two or more receptacles  122 , and the range adjustment lever  111  may include a projection  124  engageable by any one of the two or more receptacles. The projection  124  may be included as part of the first portion  114  of the range adjustment lever  111 , but this is not necessary. In some illustrative examples, a projection may be provided as part of a second portion of a range adjustment lever  111 , or be configured with respect to the range adjustment lever in any other suitable manner. When the projection  124  is engaged by any one of the two or more receptacles  122 , their engagement may substantially prevent rotation of the range adjustment lever  111  relative to the plate  120  and thus the housing  106 , which in effect “locks” the range adjustment lever to a lock position defined by a receptacle. 
     The range adjustment lever  111  may be manipulatable from the front side of the housing  106  to disengage the projection  124  from any one of the two or more receptacles  122 , to rotate the range adjustment lever, and to engage the projection with another one of the two or more receptacles, thereby allowing adjustment of the rotational position of the range adjustment lever between two or more discrete locations. The range adjustment lever  111  may include or incorporate a spring lever, for example, the first portion  114  of the range adjustment lever may comprise a suitably elastic material, such an appropriate metal of suitable thickness. The “springy” or resilient range adjustment lever  111  may be configured such that when a force is applied to the range adjustment lever toward the back of the housing  106  (e.g., via pressing range adjustment knob  110  toward the back), the projection  124  of the range adjustment lever may disengage from any one of the two or more receptacles  122  of the plate  120 , releasing the range adjustment lever for rotation to a new position. Alternatively, in some illustrative examples, the relationship between a range adjustment lever and plate may be somewhat different, such that force is applied to the range adjustment lever toward the front of the housing to disengage a projection from a receptacle to release the range adjustment lever for rotation to a new position. 
     In another example, it is contemplated that the range adjustment lever  111  may be configured to be pushed in a direction radially away from the output shaft  102  to disengage the projection from the two or more receptacles, after which the range adjustment lever  11  may be rotated to align the projection with a newly selected one of the two or more receptacles. The range adjustment lever  111  may then be pushed radially toward the output shaft  102  to engage the projection with the newly selected receptacle. In yet another example, it is contemplated that the range adjustment lever  111  may be configured to be pushed in a direction radially toward the output shaft  102  to disengage the projection from the two or more receptacles, after which the range adjustment lever  11  may be rotated to align the projection with a newly selected one of the two or more receptacles. The range adjustment lever  111  may then be pushed radially away from output shaft  102  to engage the projection with the newly selected receptacle. 
       FIG. 5  is a schematic perspective view of illustrative HVAC actuator  100  from the same viewpoint as  FIG. 4 , but with the housing  106  and plate  120  removed, showing further details of the range adjustment lever  111  and the operation of the range adjustment mechanism. The illustrative HVAC actuator  100  may include a tab  126  rigidly connected to the output shaft  102 , and the range adjustment lever  111  may move a mechanical stop  128  configured to limit the rotation of the output shaft when the tab  126  is rotated into contact with the mechanical stop  128 . The mechanical stop  128  may be integral to the range adjustment lever  111 , but this is not required. When the mechanical stop  128  is integral to the range adjustment lever  111 , then it may be substantially fixed or “locked” relative to the housing  106  of the HVAC actuator  100  when the projection  124  of the range adjustment lever  111  is engaged by a receptacle  122  of the plate  120 . 
     As described herein, the range adjustment lever  111  may allow a user to select any provided stop position (for example, corresponding to discrete locations of the range adjustment lever that correspond to receptacles  122 , which may also correspond to indicated positions “1”, “2”, and “3”) or a no stop position (for example, corresponding to a receptacle of the plate  120  that corresponds to indicated position “0”) of the output shaft  102 , where the stop positions prevent the output shaft  102  from rotating completely to the first end position, and the no stop position allows the output shaft to rotate completely to the first end position. Indicator  112  may visually indicate which stop position if any has been selected. 
     While an HVAC actuator having a single range adjustment lever  111  is illustrated, it is contemplated that a second range adjustment lever (not shown) may also be provided, such that both first and second stops in either direction of motion for an HVAC actuator may be provided. That is, in some embodiments, there may be two adjustment levers provided; one for controlling one end (e.g. more closed end) of the desired range of motion and another for controlling the other end (e.g. more open end) of the desired range. 
     The present disclosure contemplates a method for adjusting a range of motion of an HVAC actuator such as HVAC actuator  100 . The method may include the steps of manipulating an adjustment lever from the front side of the housing to unlock the adjustment lever from a first lock position, moving the adjustment lever along a path to a second lock position, and releasing the adjustment lever to lock the adjustment lever in the second lock position. At least one of the first lock position and the second lock position may establish a stop position that limits rotation of the output shaft from reaching an end position of a full range of rotation motion between a first end position and a second end position. As described further detail herein, manipulating the adjustment lever may include pressing the lever in a direction that is toward the back side of the HVAC actuator, but other mechanisms are also contemplated. 
     The position of range adjustment knob  110  relative to indicator  112  may afford a technician the ability to easily visually assess the current setting of the range adjustment mechanism of the HVAC actuator  100 . HVAC actuator  10  may include other features that allow easy visual assessment of the state of the actuator.  FIG. 6  is a schematic perspective view of illustrative HVAC actuator  100  showing, among other features, a faceplate  130  on the front side of the actuator that may display useful information. Faceplate  130  may include a first window  132  and a second window  134  positioned to provide visibility to an observer external the housing of light from corresponding light sources disposed within the housing. The first window  132  may be a component of a “closed” indicator and the second window  134  may be a component of an “open” indicator, but this is not limiting and other configurations may be used in other examples. Windows  132 ,  134  may include lenses, diffractive or diffusive patterning, or any other suitable light redirection features that may help disperse or otherwise increase the viewing angle of the windows to an observer external the housing, when viewing light from light sources within the housing. Faceplate  130  may be considered to be a component of the housing  106 . 
     To indicate the current operation of the HVAC actuator  100  to the technician, first light may have a first color (which may be red, for example, although this is arbitrary and any desired color may be chosen), and may be visible in first window  132  when the actuator is being actuated toward the first end position. First light may appear to blink (e.g., varying significantly in intensity versus time) in first window  132  when the output shaft  102  is rotating toward the first end position, and in some cases, may remain continuously visible with substantially constant intensity when the output shaft is disposed at the first end position or a first stop position, which may correspond to a damper closed state or damper partial closed state. If, on the other hand, the actuator is being actuated toward the second end position, the second light having a second color (which may be green, for example) may be visible in second window  134 . Second light may appear to blink in second window  134  when the output shaft  102  is rotating toward the second end position, and in some instances, may remain continuously visible with essentially constant intensity when the output shaft  102  is disposed at the second end position or a second stop position, which may correspond to a damper open state or damper partial open state. In some cases, HVAC actuator may be configured such that at most one of first window  132  and second window  134  transmits first or second light, respectively, at any given time. 
     Costs associated with implementing the light indication patterns described herein may be reduced by adopting what may be described as a mechanical shutter or mechanical aperture approach to modulating the light visible through the first window  132  and/or the second window  134 , when compared to other approaches potentially involving switches, wiring, electronic logic, and the like.  FIGS. 6-13  illustrate such an approach. 
       FIG. 7  is a schematic perspective view of illustrative HVAC actuator  100  of  FIG. 6 , but with the faceplate  130  removed.  FIG. 8  is a schematic perspective view of illustrative HVAC actuator  100  of  FIG. 7  with the housing  106  also removed. An aperture member or wheel  136  is shown in  FIGS. 7 and 8 , but is removed in the schematic perspective view of  FIG. 9 . In  FIG. 9 , a first light source  138  and a second light source  140  are shown disposed on circuit board  142 . First light source  138  and second light source  140  may be configured to provide first light having a first color and second light having a second color, respectively. Light sources  138 ,  140  may be light emitting diodes (LEDs), but this is not required and may be any suitable light source as desired. As may be appreciated from examination of  FIGS. 6 through 11A , first window  132  may be aligned and positioned to provide visibility of the first light from the first light source  138  to an observer external the housing  106 , and second window  134  may be aligned and positioned to provide visibility of the second light from the second light source  140  to the observer. First light and second light may be visible via first and second windows  132 ,  134  if there is no obstruction between first and second light sources  138 ,  140  and their respective first and second windows  132 ,  134 . Aperture member/wheel  136  may be situated between the light sources  138 ,  140  and the windows  132 ,  134  and may, depending on its spatial disposition, obstruct or not obstruct the light from reaching the windows  132 ,  134 . Aperture member/wheel  136  may have a plurality of spaced openings  151 ,  152 ,  153 ,  154 ,  155 , and  156  through which light may pass unobstructed. Between the spaced openings  151 - 156 , the aperture member/wheel  136  may be substantially opaque and obstruct the passage of light, although it is not necessary for the passage of light to be obstructed completely. In some illustrative examples, solid portions of the aperture wheel may partially obstruct and partially transmit light. In other illustrative examples, solid portions of the aperture wheel may completely obstruct light. 
     In some instances, aperture member/wheel  136  may be operatively coupled to the output shaft  102  of HVAC actuator  100  in any suitable way, directly or indirectly. Being so coupled, aperture member/wheel  136  may rotate as the output shaft is rotated. In some illustrative examples, aperture member/wheel  136  may be coupled indirectly to the output shaft  102  through one or more gears, and rotate in accordance with a gearing ratio with respect to the rotation of the output shaft. In the illustrative example of HVAC actuator  100 , aperture member/wheel  136  may be directly coupled relative to the output shaft  102  and may rotate at the same rotational rate as the output shaft  102 . Aperture member/wheel  136  may be coupled to or integrally formed with an arm  144 , as best seen in  FIG. 8 . Arm  144  may in turn be coupled to output shaft  102 . Such coupling may be via a coupling member  146 , which may be rigidly coupled to the output shaft  102 . The arrangement of output shaft  102 , coupling member  146 , and arm  144  illustrated in  FIG. 8  may provide a mechanism to transfer rotational motion directly from the output shaft  102  disposed generally at the back side of the HVAC actuator  100  to the aperture member/wheel  136  at the front side of the actuator. Aperture/member wheel  136  may be round in shape, although this is not necessary. Aperture/member wheel  136  may rotate about a common rotation axis as the output shaft  102 , although this is not necessary. 
       FIGS. 10A-E  are schematic perspective views from the front side of HVAC actuator  100  of faceplate  130  (rendered in phantom) with first window  132  and second window  134 , aperture member/wheel  136 , and circuit board  142  with first light source  138  and second light source  140 , with other components of the actuator omitted for clarity.  FIGS. 10A-E  all show the same components of HVAC actuator  100 , but with aperture member/wheel  136  disposed at different rotational positions as it rotates with output shaft  102 . At various rotational positions, there generally may be different alignments between aperture member/wheel  136  (and more particularly, the openings  151 - 156  of the aperture wheel) and the light sources  138 ,  140 , as well as windows  132 ,  134 , as described in the following paragraphs. 
     In  FIG. 10A , HVAC actuator  100  may be disposed in a damper fully open state, with output shaft  102  rotated fully to the second end position. Opening  153  of the aperture member/wheel  136  is aligned and in registration with second light source  140  such that if the second light source is illuminated, its light is visible through second window  134 . Second light source  140  may be illuminated when HVAC actuator  100  is electrically commanded to open, as discussed further elsewhere herein. Note that first light source  138  is not visible through any of openings  151 - 156 , as none of the openings are in registration with the first light source. In other illustrative examples, there may be an opening in registration with the first light source  138  when the output shaft  102  is rotated fully to the second end position. 
       FIG. 11A  is a schematic cross sectional view of faceplate  130  with first window  132  and second window  134 , aperture member/wheel  136 , and circuit board  142  with first light source  138  and second light source  140 , with other components of the actuator omitted for clarity. The relative alignment of windows  132 ,  134 , aperture member/wheel  136 , and light sources  138 ,  140  is substantially the same as that illustrated in  FIG. 10A . In this view, one may appreciate the alignment and registration of opening  153  relative to second light source  140  such that if the second light source is illuminated, its light is visible through second window  134 . Also as in  FIG. 10A , none of the openings  151 - 156  of aperture member/wheel  136  are registered with the first light source  138 , such that the aperture wheel  136  obstructs the path of light from the first light source  138  to the first window  132 . 
     In  FIG. 10B , the output shaft  102  and the aperture member/wheel  136  are rotated counter-clockwise relative to  FIG. 10A . Opening  151  of the aperture member/wheel  136  is aligned and in registration with first light source  138  such that if the first light source is illuminated, its light is visible through first window  132 .  FIG. 10B  could illustrate an instant in time as HVAC actuator  100  is in the process of rotating the output shaft toward a closed or partially-closed state, having started, for example, in the open state illustrated in  FIG. 10A . When HVAC actuator  100  is electrically commanded to close, first light source  138  may be illuminated continuously, as discussed further elsewhere herein. However, light from first light source  138  may only be visible through first window  132  to an observer when an opening of the aperture member/wheel  136  is aligned with the light source  138 , as is opening  151  in  FIG. 10B . In the example of an HVAC actuator  100  commanded to close from an open state (as in  FIG. 10A ), the state illustrated in  FIG. 10B  may be the first time light from illuminated first light source  138  may be visible to an observer, having appeared to have blinked on as opening  151  rotated into alignment with the first light source  138 , despite the fact that first light source  138  may have been illuminated continuously from the earliest moment that the actuator was commanded to close, when solid portions of aperture member/wheel  136  may have obstructed light from the first light source  138  from reaching the first window  132 . 
     In  FIG. 10C , the output shaft  102  and the aperture member/wheel  136  are rotated further counter-clockwise relative to  FIG. 10B . First light source  138  is not visible, with an obstructing portion of aperture member/wheel  136  between openings  151  and  152  being positioned over the light source. None of openings  151 - 6  are aligned and in registration with first light source  138 . Continuing the example of an HVAC actuator  100  being commanded to close, an observer may have perceived light from illuminated first light source  138  to have blinked off as the obstructing portion between openings  151  and  152  rotated into the position of  FIG. 10C  from the previous position of  FIG. 10B . Even though the first light source  138  may have remained illuminated during the rotation of output shaft  102  and aperture member/wheel  136 , the effective appearance from outside the housing  106  of the HVAC actuator may be that the first light is turning on and off (blinking) as openings and obstructions of the aperture wheel  136  alternate in passing between the first light source  138  and the first window  132 . Some or all openings  151 - 156  may be configured to cause the appearance of blinking of the first light from first light source  138  through the first window  132  as the output shaft  012  is rotated toward the first end position. 
     In  FIG. 10D , the output shaft  102  and the aperture member/wheel  136  are rotated further counter-clockwise relative to  FIG. 10C . Opening  154  is aligned and in registration with first light source  138  such that if the first light source  138  is illuminated, its light is visible through first window  132 . The position of aperture member/wheel  136  may correspond to a damper partially-closed stop position selected via the range adjustment mechanism of HVAC actuator  100 , for example, range stop position “2”. In an example where the range stop position “2” has been selected, first light from first light source  138  may remain continuously visible through opening  154  and first window  132  if the first light source  138  remains illuminated, as may be the case when the HVAC actuator is being commanded to be closed. Similarly as in the state illustrated in  FIG. 10D , openings  153  and  155  may correspond to range stop position “3” and “1” respectively such that they may be aligned and in registration with first light source  138  when the output shaft  102  is stopped at one of those positions. 
     In  FIG. 10E , the output shaft  102  and the aperture member/wheel  136  are rotated further counter-clockwise relative to  FIG. 10D . Opening  156  is aligned and in registration with first light source  138  such that if the first light source  138  is illuminated, its light is visible through first window  132 . The position of aperture member/wheel  136  may correspond to an actuator state with the output shaft  102  rotated completely to the first end position, which may correspond to a damper fully closed state. If HVAC actuator  100  continues in a state of being electrically commanded to close, as discussed further elsewhere herein, first light source  138  may remain illuminated and its light may remain continuously visible through first window  132  for as long as it continues in that state. 
     With the output shaft stopped at any of range stop positions “1”, “2” (such as in  FIG. 10D ), or “3”, or no stop position “0” (such as in  FIG. 10E ), second light source  140  may remain obscured by aperture member/wheel  136 , with none of the openings  151 - 156  aligned and in registration with the second light source  140 . In other illustrative examples, there may be aperture member openings aligned with the second light source  140  when the output shaft is stopped at a first stop or end position. 
     The discussion of  FIGS. 10A-10E  may generally describe a progression starting at  FIG. 10A  with output shaft  102  rotated fully to the second end position which may correspond to a damper fully open state, and progressing to  FIG. 10E , with the output shaft  102  rotated fully to the first end position which may correspond to a damper fully closed state. In the progression of  FIGS. 10B-10E , which may depict the aperture member/wheel  136  rotating counter-clockwise as the output shaft  102  rotates counter-clockwise toward the first end of the rotation range, first light source  138  may be continuously illuminated, with the alternating pattern of openings and obstructions of the aperture wheel  136  helping to create the appearance of blinking of first light as viewed via first window  132 . The aperture member/wheel  136  may likewise modulate second light from second light source  140 , when the second light source is illuminated. The second light source  140  may be illuminated when HVAC actuator  100  is electrically commanded to rotate the output shaft  102  toward the second end of its range, which may correspond to a damper open state. In such a condition, the second light source  140  may be illuminated continuously whether the output shaft  102  is rotating toward the second end of its range, or whether it stationary at the second end of its range. As may be appreciated from  FIG. 10A , where opening  153  is aligned and in registration with second light source  140 , and openings  154 ,  155 , and  156  are disposed clockwise relative to the second light source  140 , openings  153 - 156  may participate in providing varying patterns of second light. 
     It is contemplated that any appropriate patterns of openings, including variations in the quantity of openings, may be provided on an aperture member to results in light patterns similar to those described herein. Other arrangements are contemplated. In some illustrative examples, light sources may be disposed at different radii relative to the axis of rotation of the aperture member/wheel  136 , and separate patterns of openings at corresponding radii may exclusively modulate the light output of the different light sources. Also, the openings need not be defined on all sides by the aperture member. For example, in some cases, the perimeter of the aperture member may undulate inwardly at certain locations to form corresponding openings. 
     Other configurations for indicator lights in HVAC actuators are contemplated.  FIG. 12  is a schematic illustration of a faceplate  160  of an HVAC actuator similar to HVAC actuator  100 . Faceplate  160  has a single indicator window  162 . An HVAC actuator having faceplate  160  with single indicator window  162  may be configured with a light source corresponding to the single indicator window and a moving aperture member that modulates visibility of light from the light source via the single indicator window in a manner like or similar to that of the system of  FIGS. 6-11A . Such an HVAC actuator may be configured such that the light source only illuminates when the actuator is powered to drive its output shaft in one direction (for example, in a damper open direction), but not when the actuator moves the output shaft in the other direction (for example, the closed direction). As described elsewhere herein, such an HVAC actuator may be powered only to drive its output shaft in the one direction, and may move the output shaft in the other direction when unpowered, for example, through the action of a return spring. In some instances, an HVAC actuator having faceplate  160  of  FIG. 12  may be a damper actuator for a venting or bypass applications. 
       FIG. 11B  is a schematic cross sectional view of an actuator faceplate  170  with an indicator window  172 , an aperture member  174 , and circuit board  176  with light source  178 . In an illustrative example, the arrangement of  FIG. 11B  may be similar to that of  FIG. 11A , but with only a single window and light source rather than two. In another illustrative example, the arrangement of  FIG. 11B  may correspond to or be compatible with faceplate  160  of  FIG. 12 . The arrangement of  FIG. 11B  may correspond to still yet another example, in which light source  178  may be capable of emitting multiple colors of light independently. This may be accomplished with multiple LED emitters, but it is contemplated that any suitable technology may be used. Such an arrangement could be operated with a first color emitted when the actuator is actuated in a first direction, and a second color when actuated in a second direction. The same openings in aperture member  174  may modulate the transmission of either color of light. 
       FIG. 13  is a schematic illustration of another illustrative example of an aperture member  220  that may be configured to modulate light for an HVAC actuator in a manner similar to aperture member/wheel  136 . Aperture member  220  may translate as the output shaft of the HVAC actuator of which it is a component is rotated. Aperture member  220  may be linked to output shaft motion via a rack-and-pinion mechanism  222 . Openings  224  may provide a like function as openings  151 - 156  of aperture member/wheel  136 . While a rack-and-pinion mechanism is shown in  FIG. 13  to produce a linear motion for the aperture member  220 , it is contemplated that any suitable translation mechanism may be used to move a number of apertures relative to one or more light sources. 
     The present disclosure contemplates a method for operating an HVAC actuator having the indicator features described in connection with  FIGS. 6-12 . The method may include the steps of rotating an output shaft toward a first end position and stopping rotation of the output shaft when the output shaft reaches the first end position. The method may also include the step, as the output shaft  102  is rotated toward the first end position, of moving an aperture member  136 . The aperture member  136  may have two or more spaced openings that transmit a first light from a first light source  138  to a first window  132  of a housing at each of two or more positions of the output shaft  102 , where the two or more openings of the aperture member  136  are configured to cause the appearance of blinking of the first light through the first window  132  as the output shaft  102  is rotated toward the first end position, and remaining lit when the output shaft  102  is at the first end position. The method may further include the steps of rotating the output shaft  102  toward a second end position and stopping rotation of the output shaft  102  when the output shaft reaches the second end position. The method may also include the step, as the output shaft  102  is rotated toward the second end position, of moving the aperture member  136 . The two or more spaced openings of the aperture member  136  may be configured to transmit a second light from a second light source  140  to a second window  134  of the housing at each of two or more positions of the output shaft  102 , where the two or more openings of the aperture member  136  are configured to cause the appearance of blinking of the second light through the second window  134  as the output shaft  102  is rotated toward the second end position and remaining lit when the output shaft  102  is at the second end position 
     The illuminated indicators provided via first and second windows  132 ,  134  may allow a technician a convenient visual information display of whether HVAC actuator  100  is being supplied power to be driven or to move in the first or the second direction, and may allow the technician to quickly perceive whether the actuator is actually rotating its output shaft  102 , via blinking modulated by the moving aperture member/wheel  136 . HVAC actuator  100  may provide further visual indicators of its current status. HVAC actuator  100  may include a position indicator viewable from the front side of housing  106  that moves as the output shaft  102  is rotated such that the position indicator indicates a current position of the output shaft. Aperture member/wheel  136 , which is operatively coupled to the output shaft  102  of HVAC actuator  100  and rotates with the output shaft, may serve as an indicator wheel for the position indicator. However, it is not required that aperture member/wheel  136  also serve as an indicator wheel of a position indicator, and in some illustrative examples, an HVAC actuator may include an indicator wheel operatively coupled to the output shaft  102  of the HVAC actuator that rotates with the output shaft  102  as a component of a position indicator that does not also serve as an aperture wheel. 
     In some cases, aperture wheel  136  may include one or more markings that move with the indicator wheel and that are viewable from the front side of the housing  106 . Such markings may include a line  180  extending in a radial direction from the rotation axis of the aperture wheel  136  (see  FIGS. 6-8 and 10A-10E ). Line  180  and any other provided markings may be viewable through a window of the housing  106 , such as window  182  of faceplate  130  (see  FIG. 6 ). Window  182  may be a transparent solid material, but this is not necessary, and in other illustrative examples, a window for viewing markings of an indicator wheel may simply be an opening in a housing. In the example shown, faceplate  130  of housing  106  may include one or more position indicia  184  that may, when used in conjunction with the one or more markings of the indicator wheel such as line  180 , indicate when the output shaft  102  is at one or more predetermined positions. For example, indicium “0” of indicia  184  may indicate when the output shaft is at a position corresponding to the second end of the range of motion, which may be when the damper is fully closed. The indicia “1”, “2”, and “3” of indicia  184  of the position indicator may indicate when the output shaft is at the stop positions corresponding to the “1”, “2”, and “3” indicia of indicator  112  of the range adjustment mechanism. For example, a technician may manipulate the range adjustment mechanism by moving range adjustment knob  110  of the range adjustment lever  111  to the position corresponding to indicium “1” of indicator  112 . The range of motion of the output shaft  102  may then be limited to a range between fully open at 0 degrees and stop position “1”, which may be at, for example, 80 degrees. As the output shaft is actuated in this range, line  180  may move with aperture wheel  136  such that at its furthest counter-clockwise rotation, it reaches indicium “1” of indicia  184  of the position indicator (as illustrated as an example in  FIG. 6 ) but may not rotate further, as the motion of the output shaft is stopped by the range adjustment mechanism. 
     Aperture wheel  136  may be directly coupled to the output shaft  102  of the HVAC actuator  100  such that it rotates directly with the output shaft. When so provided, a given rotational displacement of the output shaft  102  may result in an identical rotation displacement of the aperture wheel  136 . For example, 47 degrees of rotation of the output shaft  102  may be coupled directly to the aperture wheel  136  to result in an identical 47 degrees of rotation of the indicator wheel. During installation of the HVAC actuator  100 , line  180  may be aligned with the plane of the damper blade  52  such that after installation, a technician may be able to immediately visually ascertain the actual angular disposition of the damper blade (which, being within the duct  30 , may not be visible directly) simply from inspection of the position of line  180  of the position indicator, which may remain aligned with the plane of the damper blade. 
     Alternatively to a position indicator wheel such as wheel  136 , other arrangements are contemplated. For example,  FIG. 13  illustrates an aperture member  220  that translates rather than rotates. Aperture member  220  may also serve as a position indicating member and include one or more markings  226  that may be viewable from the front side of a housing of an HVAC actuator, and which may be used in conjunction with position indicia on the housing to provide an indication of the current position of an output shaft. In some illustrative examples, a translating position indicating member may be provided that is not also an aperture member. 
     The present disclosure contemplates a method for operating n HVAC actuator such as HVAC actuator  100  having the position indicator features described herein. The method may include the steps of rotating an output shaft  102  extending from a back side of the HVAC actuator  100  moving a position indicator in proportion to the rotation of the output shaft  102 . The position indicator may have markings and/or indicia that indicate a current position of the output shaft  102 . The method may also include the step of displaying the indicia of the position indicator through a window on a front side of the HVAC actuator. The position indicator may comprise an indicator wheel, and the moving step may comprise rotating the indicator wheel about a common rotation axis as the output shaft, but this is not required. 
     As discussed herein, an HVAC actuator of the present disclosure may be configured to selectively output rotational motion via an output shaft  102  in a first direction and a second direction. Generally, an HVAC actuator of the present disclosure may be electrically controllable. In some illustrative examples, electrical power for actuator operation and control signals may be provided separately. In some instances, the supply of electrical voltage and current at electrical terminals of an HVAC actuator may provide both the signal for a desired actuator operation and electrical power to implement that operation. 
     Some HVAC actuators that provide output rotational motion via an output shaft  102  in a first direction and a second direction require electrical power for motion in each direction, and may be referred to as bi-directionally powered actuators. Some bi-directionally powered actuators may be provided with three or more wiring terminals, including a common terminal, a first terminal for commanding rotation in the first direction, and a second terminal for commanding rotation in the second direction, whereupon when either of the first or second terminals is asserted by being supplied with appropriate voltage and/or current, an electric motor may drive the output shaft in the corresponding direction. A remote HVAC controller for such a bi-directionally powered HVAC actuator may be required to provide appropriate control signals to the three or more wiring terminals to achieve proper actuator operation in both the first and the second directions. Such a controller may be referred to as a bi-directional controller. 
     Some HVAC actuators may only require electrical power for motion in one of two directions, and may be referred to as uni-directionally powered actuators. Some uni-directionally powered actuators may be provided with only two wiring terminals, whereupon when the terminals are asserted by being supplied with appropriate voltage and/or current, an electric motor may drive the output shaft in one of the two directions. When electrical power is not asserted at the terminals, a return spring of the actuator may move the output shaft  102  in the other of the two directions. An advantage of a uni-directionally powered HVAC actuator is that it may provide “failsafe” operation. That is, in the event of power loss, the return spring may move the output shaft  102  to actuate the HVAC component (e.g., damper, valve, etc.) in a preferred power loss direction. As discussed elsewhere herein, such uni-directionally powered actuators may be available in “normally open” and “normally closed” versions, corresponding to the default state of the actuator in an unpowered or power loss condition. A remote HVAC controller for a such a uni-directionally powered actuator having only two wiring terminals may be configured to provide a control signal via two wires when motion in the electric motor driven direction is desired, and no signal when motion in the default return spring driven direction is desired. Such a controller may be referred to as a uni-directional controller. Faceplate  160  of  FIG. 12  may be a component of a uni-directionally powered HVAC actuator having two wiring terminals. Markings  164  label the two wire terminals, which may be unpolarized. In an HVAC actuator having faceplate  160 , single indicator window  162  may illuminate (whether blinking or continuously) only when power is applied to the actuator via the two wire terminals, and may remain un-illuminated when power is not applied via the two wire terminals. 
     In some cases, an HVAC controller that is configured to provide signals to a bi-directionally powered HVAC actuator via three wire terminals may be used to control a uni-directionally powered actuator that only includes two wire terminals. In such a case, two of three wire connections provided by the HVAC controller may be connected to the two wire terminals of the actuator: the common wire connection, and the appropriate one of the first or second direction wire connection, with the other direction wire connection being left unconnected. In such a case, when the actuator is not powered via the two wire terminals, the actuator may not provide any illuminated indications of actuator status. 
     The present disclosure contemplates uni-directionally powered HVAC actuators that include three wiring terminals, and which may be controlled either by a uni-directional HVAC controller with two wires, or by a bi-directional HVAC controller with three wires, and also include features to help prevent miss-wiring of the actuator. 
       FIG. 14  is a schematic perspective view of the illustrative HVAC actuator  100  showing details of three wiring terminals  190 ,  192 , and  194 . The three wiring terminals may be designated M1 ( 190 ), M4 ( 192 ), and M6 ( 194 ), as labeled on faceplate  130 , but this is merely exemplary and is not required. HVAC actuator  100  may include a removable blocking tab  196  configured to block wire attachment to at least one of the wiring terminals. As illustrated, removable blocking tab  196  blocks wire attachment to wiring terminal  192 , which is the second and middle of the three wiring terminals  190 ,  192 ,  194 . However, any suitable wiring terminal or terminals may be blocked by one or more removable blocking tabs, depending on the configuration of the HVAC actuator. Removable blocking tab  196  may be a break-away tab, and may be referred to as a break-away blocking tab. Removable blocking tab  196  may be integral to housing  106 . Removable blocking tab  196  may be configured such that once removed, it is not configured to be reattached. HVAC actuator  100  may be configured such that once a removable blocking tab, such as removable blocking tab  196 , is removed, wire attachment to the previously blocked wire terminal(s) is/are no longer blocked. 
     In some cases, the removable blocking tab  196  may not be a break-away tab. In one example, the removable blocking tab may be hinged, and may be rotated out of the way by an installer to expose previously blocked wiring terminal(s). In another example, the removable blocking tab may be slide out of the way by the installer to expose previously blocked wiring terminal(s). These are just some examples. 
       FIG. 14  shows in illustrative HVAC actuator  100  with removable blocking tab  196  in place. The HVAC actuator may be suited for wired connection to a uni-directional HVAC controller that provides signals over two wires. The two unblocked wiring terminals M1 ( 190 ) and M6 ( 194 ) may receive the two wires from the uni-directional HVAC controller. HVAC actuator  100  may be configured with M1 ( 190 ) as electrical common, and M6 ( 194 ), when asserted, may cause the drive mechanism to drive the output shaft  102  toward the first end direction or position, which may be a more closed direction or position in comparison with the second end direction or position. However, in other examples, the first end direction or position may be a more open direction or position in comparison with the second end direction or position. HVAC actuator  100  may be configured to drive toward the first end direction with the two wires from the unidirectional controller attached to M1 ( 190 ) and M6 ( 194 ) with either polarity. When HVAC actuator  100  is powered via M1 ( 190 ) and M6 ( 194 ) to drive output shaft  102  toward the first end direction or position, the first light source  138  may be continuously illuminated or activated and the second light source  140  may be deactivated. When HVAC actuator  100  is not powered via M1 ( 190 ) and M6 ( 194 ), a return spring may drive the output shaft  102  toward the second end position, and first light source  138  may be non-illuminated. With terminal M4 ( 192 ) not asserted, as may be the case when it is blocked by removable blocking tab  196 , second light source  140  may also be non-illuminated. 
     The same HVAC actuator  100 , but configured with removable blocking tab  196  removed (not illustrated), may be suited for wired connection to a bi-directional HVAC controller that provides signals over three wires. In this instance, HVAC actuator  100  may be configured with M1 ( 190 ) as electrical common, and M6 ( 194 ), when asserted, may cause the drive mechanism to drive the output shaft  102  toward the first end direction or position, which may be a more closed direction or position in comparison with the second end direction or position. However, in other examples, the first end direction or position may be a more open direction or position in comparison with the second end direction or position. Additionally, when M6 ( 194 ) is asserted, the first light source  138  may be continuously illuminated or activated and the second light source  140  may be deactivated. When M6 ( 194 ) is not asserted, the first light source  138  may be deactivated and a return spring may drive the output shaft  102  toward the second end position. When M4 ( 192 ) is asserted, the second light source  140  may be continuously illuminated or activated, but there may be no electrical power applied to the drive mechanism of the HVAC actuator. Usually, if M4 ( 192 ) is asserted, the bi-directional controller will not also assert M6 ( 194 ), and the return spring may drive the output shaft  102  toward the second end position. However, if under unusual circumstances and both M4 ( 192 ) and M6 ( 194 ) are asserted, both first and second light sources  138 ,  140  may be illuminated, and the drive mechanism may drive the output shaft  102  toward the first end direction or position. In this unusual circumstance, upon the output shaft  102  reaching the first end or a first stop position and ceasing motion, the pattern of openings  151 - 156  of aperture member/wheel  136  may result in the appearance of first light in first window  132  and non-appearance of light in second window  134  to an observer viewing the front of the housing  106 . Before the output shaft  102  ceases motion in this unusual circumstance, blinking of light may be observed in both first and second windows  132 ,  134 , indicating a wiring or other error condition. 
     The inclusion of removable blocking tab  196  in the design of HVAC actuator  100  may help reduce the chance of miss-wiring the HVAC actuator. By default, the HVAC actuator  100  may be provided to a technician with removable blocking tab  196  intact. If using a uni-directional HVAC controller that provides two wires to control the actuator, then with removable blocking tab  196  in place, only two wiring terminals, for example M1 ( 190 ) and M6 ( 194 ), are readily accessible and the wires from the uni-directional HVAC controller may be coupled to these unblocked terminals without confusion. The removable blocking tab  196  may help prevent miss-wiring to the blocked wiring terminal, for example, M4 ( 192 ). If, on the other hand, a bi-directional HVAC controller that provides three wires is used, the removable blocking tab  196  may be removed, and the three wires may be coupled to the appropriate wiring terminals  190 ,  192 ,  194 . 
     HVAC actuator  100  may include wire guides  200 ,  202 ,  204  associated with each of wire terminals  190 ,  192 ,  194 . Each wire guide  200 ,  202 ,  204  may be regarded as an integral component of each wire terminal  190 ,  192 ,  194 , or it may be regarded as a separate accessory for its associated wire terminal. Each wire guide  200 ,  202 ,  204  may define an aperture for receiving and guiding an end of a corresponding wire to a corresponding one of the wiring terminals  190 ,  192 ,  194 . First, second, and third wire guides  200 ,  202 ,  204  may be formed from a common part. A removable blocking tab may be situated in front of the aperture of a wire guide corresponding to a wire terminal  190 ,  192 ,  194  to help prevent inadvertent connection of a wire to that terminal. For example, removable blocking tab  196  may be situated in front of the aperture of wire guide  202  of second wire terminal M4 ( 192 ) to help prevent inadvertent connection of an improper wire to the second wire terminal, for example, in a case where a uni-directional HVAC controller that provides two wires is employed to control the HVAC actuator  100 . 
     Each wire terminal  190 ,  192 ,  194  may be configured to allow a wire to be inserted manually without the aid of tools, and, after insertion, to retain the wire firmly. Each wire terminal  190 ,  192 ,  194  may include a corresponding release button  191  that, when pressed, actuates a release mechanism that allows insertion and removal of a wire from the terminal without tools. In some instances, HVAC actuator  100  may include integrated wire strain relief features. For example, HVAC actuator  100  may include wire wrap posts  197 , around which wires attached to the wire terminals  190 ,  192 ,  194  may be wrapped. Wrapping a wire attached to a wire terminal  190 ,  192 ,  194  around a post  197  may isolate or buffer the end of the wire inserted into the terminal from mechanical forces applied to the wire on the other side of the wrap around the post, helping to prevent undesired detachment of the wire from the terminal. 
     The present disclosure contemplates a method for connecting two or more wires to an HVAC device, such as HVAC actuator  100 , including the step of identifying which of two or more wiring terminals of the HVAC device need to be connected to a wire. At least one of the two or more wiring terminals of the HVAC device may have a removable blocking tab that blocks access to the corresponding wiring terminal. If a wire needs to be connected to the at least one of the two or more wiring terminals that has a removable blocking tab that blocks access to the corresponding wiring terminal, the method may include the step of removing the removable blocking tab and then connecting a wire to the corresponding wiring terminal. The removable blocking tab may be a break-away blocking tab, in which case removing the removable blocking tab may include breaking away the break-away blocking tab. A break-away blocking tab, once broken-away, may not be configured to be reattached. If a wire needs to be connected to one or more of the two or more wiring terminals that does not have a removable blocking tab that blocks access to the corresponding wiring terminal, the method may include the step of connecting a wire to the corresponding wiring terminal. 
     HVAC actuator  100  may include a controller for controlling the drive mechanism, the first light source  138  and the second light source  140 . The controller may be disposed on a circuit board  142 . The controller may be configured to activate the first light source  138  and deactivate the second light source  140  when the drive mechanism is driving the output shaft  102  toward the first end position. The controller may further be configured to activate the second light source  140  and deactivate the first light source  138  when the output shaft  102  is moved toward the second end position. Output shaft  102  may be moved toward the second end position as a result of force exerted by a return spring  306 . Alternately, in another example, the drive mechanism may be configured to selectively drive the output shaft  102  toward the second end position, and the controller may activate the second light source  140  and deactivate the first light source  138  when the drive mechanism is driving the output shaft toward the second end position. 
       FIG. 15  is a schematic partial exploded view of illustrative HVAC actuator  100 . Housing  106  is omitted in  FIG. 15 . The drive mechanism of HVAC actuator  100  may include an electric motor  300  having an output gear (not visible in this view) coupled to a drive gear  304 , which may be rigidly fixed to output shaft  102 . The drive mechanism may be configured to drive the output shaft  102  in only a single direction, for example, in a first direction which may be a damper or valve more closed direction. Return spring  306  may be configured to exert a torque on the output shaft  102  that tends to move the output shaft in a second direction, which may be a damper or valve more open direction. When the electric motor  300  of the drive mechanism is powered, the resultant torque of the drive mechanism on the output shaft  102  may overcome the torque exerted by the return spring  306  such that the output shaft rotates in the first direction, or, if the output shaft has reached the first end or a first stop, it is maintained at that end or stop position against the torque exerted by the return spring. When the electric motor  300  of the drive mechanism is not powered, the torque exerted by the return spring  306  may be sufficient to rotate the output shaft  102  in the second direction and/or maintain the output shaft at the second end or a second stop. 
     The disclosure should not be considered limited to the particular examples described above, but rather should be understood to cover all aspects of the disclosure and equivalents thereof. Various modifications, equivalent processes, as well as numerous structures to which the disclosure can be applicable will be readily apparent to those of skill in the art upon review of the instant specification.