# US 2014/0207288 A1 · Control unit for an hvac system comprising an economizer and method for operating such control unit

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- Number: US 2014/0207288 A1
- Document ID: US20140207288A1
- Status: Published application
- Kind: A1
- Application number: 13/749,007
- Filed: 2013-01-24
- Published: 2014-07-24
- Earliest claimed: 2013-01-24
- Assignees: Belimo Holding AG
- Applicants: Belimo Holding AG
- Inventors: Daniel ALBRECHT; Ronald AEBERHARD; Guido HOFSTETTER; Darryl DEANGELIS
- Web page: https://patentgrep.com/patent/US20140207288A1

## CPC

- F24F 11/0001: {for ventilation (F24F11/30 takes precedence)}
- F24F 11/52: Indication arrangements, e.g. displays
- F24F 11/88: Electrical aspects, e.g. circuits
- F24F 7/08: with separate ducts for supplied and exhausted air {with provisions for reversal of the input and output systems}
- F24F 11/30: for purposes related to the operation of the system, e.g. for safety or monitoring
- F24F 2011/0006: {using low temperature external supply air to assist cooling}
- F24F 2110/20: Humidity
- F24F 2110/22: of the outside air
- F24F: AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING (removing dirt or fumes from areas where they are produced B08B15/00; vertical ducts for carrying away waste gases from buildings E04F17/02; tops for chimneys or ventilating shafts, terminals for flues F23L17/02)

## Abstract

A control unit (22) for an HVAC system (10) comprises an economizer (EC), which economizer (EC) is configured to introduce outdoor air (OA) into the HVAC system (10) for cooling and/or ventilation purposes in a manner controlled by said control unit (22), said control unit (22) comprising a base module (23) with: a control circuit (24), a man machine interface (25) connected to said control circuit (24), and first I/O means for connecting at least one sensor (32, . . . , 36) of said HVAC system to said control circuit (24) and for delivering at least one control signal from said control circuit (24) to control the operation of said economizer (EC). Said base module (23) is configured to optionally receive at least one extension module (26, 27, 28), which can be snapped on and electrically connected to said base module (23) for expanding the functionality of said control unit (22).

## Claims

### Claim 1

A control unit (22) for an HVAC system (10) comprising an economizer (EC), which economizer (EC) is configured to introduce outdoor air (OA) into the HVAC system (10) for cooling and/or ventilation purposes in a manner controlled by said control unit (22), said control unit (22) comprising a base module (23) with: a control circuit (24), a man machine interface (25) connected to said control circuit (24), and first I/O means (39, CR1, CR2, CR3) for connecting at least one sensor (32, . . . , 36) of said HVAC system to said control circuit (24) and for delivering at least one control signal from said control circuit (24) to control the operation of said economizer (EC), whereby said base module (23) is configured to optionally receive at least one extension module (26, 27, 28), which can be snapped on and electrically connected to said base module (23) for expanding the functionality of said control unit (22).

### Claim 2 (depends on 1)

Control unit as claimed in claim 1, wherein said base module (23) is configured to receive said at least one extension module (26, 27, 28) such that the electrical connection between said at least one extension module (26, 27, 28) and said base module (23) is automatically established, when said at least one extension module (26, 27, 28) is snapped on said base module (23).

### Claim 3 (depends on 2)

Control unit as claimed in claim 2, wherein a plug-in connector (56, 57, 58, 63) is provided for electrically connecting said base module (23) and said at least one extension module (26, 27, 28), one part of said plug-in connector (56, 57, 58, 63) being integrated into said base module (23) and the other part of said plug-in connector (56, 57, 58, 63) being integrated into said at least one extension module (26, 27, 28).

### Claim 4 (depends on 1)

Control unit as claimed in claim 1, wherein said base module (23) is configured to receive a plurality of extension modules (26, 27, 28), wherein plug-in connectors (56, 57, 58, 63) are provided for electrically connecting said base module (23) and each of said extension modules (26, 27, 28), one part of each plug-in connector (56, 57, 58, 63) being integrated into said base module (23) and the other part of each plug-in connector (56, 57, 58, 63) being integrated into an extension module (26, 27, 28), whereby said plug-in connectors (56, 57, 58, 63) are individualized so that each plug-in connector (56, 57, 58, 63) can only be used with one type of extension module.

### Claim 5 (depends on 3)

Control unit as claimed in claim 3, wherein said base module (23) is provided with first latching means (62) and said at least one extension module (26, 27, 28) is provided with second latching means (61) configured to co-operate with said first latching means (62) such that said at least one extension module (26, 27, 28) is locked in place on said base module (23), when it is plugged into said plug-in connector (56, 57, 58, 63).

### Claim 6 (depends on 5)

Control unit as claimed in claim 5, wherein said first and second latching means (61, 62) comprise an elastically bendable snapping clip (61) and one or more catches (62), whereby said snapping clip (61) glides over and latches behind said catches (62), when said at least one extension module (26, 27, 28) is plugged into said plug-in connector (56, 57, 58, 63), and whereby said at least one extension module (26, 27, 28) can be released by elastically bending said snapping clip (61).

### Claim 7 (depends on 6)

Control unit as claimed in claim 6, wherein said elastic snapping clip (61) is provided at said at least one extension module (26, 27, 28), and said catches (62) are arranged at said base module (23).

### Claim 8 (depends on 1)

Control unit as claimed in claim 1, wherein said at least one extension module (26, 27, 28) is provided with second I/O means (CR4, CR5; 50, 51, 52) for electrically connecting said at least one extension module (26, 27, 28) and thereby said base module (23) with further units (18, 21, 29, 30, 37) being relevant for the operation of the HVAC system (10).

### Claim 9 (depends on 8)

Control unit as claimed in claim 8, wherein said at least one extension module (26) is configured to enable a demand controlled ventilation (DCV) operation of the HVAC system (10), and said second I/O means comprises input means for a CO2 sensor (37) and output means for controlling an exhaust fan (21) within said HVAC system (10).

### Claim 10 (depends on 9)

Control unit as claimed in claim 9, wherein said second I/O means comprise further output means for controlling an indoor fan (18) within said HVAC system (10).

### Claim 11 (depends on 8)

Control unit as claimed in claim 8, wherein said at least one extension module (27) is configured to enable a communication with remote devices (29, 30).

### Claim 12 (depends on 11)

Control unit as claimed in claim 11, wherein said remote devices (29, 30) comprise an alarm device (30).

### Claim 13 (depends on 11)

Control unit as claimed in claim 11, wherein said remote devices (29, 30) comprise a remote unit (29) for exchanging data with said control unit (22).

### Claim 14 (depends on 1)

Control unit as claimed in claim 1, wherein said base module (23) comprises a base plate (53) and a housing (54) mounted on said base plate (53), which housing (54) encloses said control circuit (24) and said man machine interface (25), whereby said housing (54) comprises on its upper side an I/O platform (38), on which said first I/O means (39, CR1, CR2, CR3) is arranged, and which is configured to receive said at least one extension module (26, 27, 28), and further comprises an MMI housing part (40), which projects from said I/O platform (38) and contains said man machine interface (25).

### Claim 15 (depends on 14)

Control unit as claimed in claim 14, wherein said first I/O means comprises a plurality of connector rows (CR1, CR2, CR3), which are arranged in a separate I/O area (39).

### Claim 16 (depends on 15)

Control unit as claimed in claim 15, wherein said at least one extension module (26, 27, 28) can be snapped on said base module (23) outside said I/O area (39) without changing the footprint of said base module (23).

### Claim 17 (depends on 15)

Control unit as claimed in claim 15, wherein each said connector row (CR1, CR2, CR3) comprises a plurality of individual male spade connectors.

### Claim 18 (depends on 1)

Control unit as claimed in claim 1, wherein said first I/O means (39, CR1, CR2, CR3) comprises first connecting means (1Act, 2Act, 3Act, 5Act) for connecting an actuator (17), second connecting means (Y1, Y2, W1) for connecting a thermostat (31), third connecting means (+SAT, −SAT) for connecting a supply air temperature sensor (34), fourth connecting means (+OAT, −OAT) for connecting an outdoor air temperature sensor (32), fifth connecting means (+OAH, −OAH) for connecting an outdoor air humidity sensor (33), sixth connecting means (+RAT, −RAT) for connecting a return air temperature sensor (35), and seventh connecting means (+RAH, −RAH) for connecting a return air humidity sensor (36).

### Claim 19 (depends on 18)

Control unit as claimed in claim 18, wherein said control circuit (24) and said sensor connecting means (+SAT, −SAT; +OAT, −OAT; +OAH, −OAH; +RAT, −RAT; +RAH, −RAH) are configured to be connected to analog sensors.

### Claim 20 (depends on 18)

Control unit as claimed in claim 18, wherein said first connecting means (1Act, 2Act, 3Act, 5Act) for connecting an actuator (17) comprises a separate connector (5Act) for receiving a feedback signal from said actuator (17), said feedback signal containing information about the actual position of said actuator (17).

### Claim 21 (depends on 18)

Control unit as claimed in claim 18, wherein said first I/O means (39, C1, C2, C3) further comprises eighth connecting means (CC1, CC2) for connecting first and second compressors of a two-stage cooling device (19) within said HVAC system (10).

### Claim 22 (depends on 1)

Control unit as claimed in claim 1, wherein said man machine interface (25) comprises a display (46) for displaying menu points, onboard information, set values and real time operating information, a plurality of push buttons (41, 42, 47, 48, 49) for inputting various commands, and a plurality of optical indicators (43, 44, 45) for indicating status information.

### Claim 23 (depends on 22)

Control unit as claimed in claim 22, wherein said display (46) is an enhanced trans-Elective backlit LCD display, especially with an extended temperature range, with two rows of 16 characters each.

### Claim 24 (depends on 22)

Control unit as claimed in claim 22, wherein said plurality of push buttons (41, 42, 47, 48, 49) comprises a separate help button (47) for retrieving and displaying context sensitive help information stored with said control circuit (24).

### Claim 25 (depends on 1)

Method for operating a control unit (22) as claimed in claim 1 to control a HVAC system (10), which comprises means (19) for cooling the air passing through said HVAC system (10), wherein said control unit (22) has to be set up by an operator before it is able to automatically control the cooling operation of said cooling means (19).

### Claim 26 (depends on 25)

Method as claimed in claim 25, wherein said economizer (EC) of said HVAC system (10) comprises a damper (D1, D2, D3) for controlling the inflow of outdoor air (OA) into the HVAC system (10), and wherein at least a minimum position of said damper (D1, D2, D3) has to be set up and a parameter representative of the climate zone at the location of said HVAC system (10), preferably the ZIP code, has to be entered before said control unit (22) is able to automatically control the cooling operation of said cooling means (19).

### Claim 27 (depends on 1)

Method for operating a control unit (22) as claimed in claim 1, wherein said man machine interface (25) comprises a display (46) for displaying menus, which contain references to devices (26, 27, 28; 32-37) attached to and connected with said base module (23), and wherein said references are automatically not shown in the menus displayed, when the respective device is not attached to and connected with said base module (23).

### Claim 28 (depends on 27)

Method as claimed in claim 27, wherein said control unit (22) has to be initially set up by an operator before it is able to automatically control the operation of said HVAC system (10), and wherein a prompt for an additional setup is generated by said base unit (23) and displayed on said display (46), when a new device is attached to and connected with said base unit (23).

### Claim 29

Method as claimed in 28, wherein a new function of said control unit (22) associated with said new device is only implemented by said control unit, when said additional setup is done.

### Claim 30 (depends on 27)

Method as claimed in claim 27, wherein context sensitive help information to be displayed an said display (46) is stored in said control circuit (24), wherein the menu displayed on said display (46) indicates, when a context sensitive help information is available for a certain menu point, and said context sensitive help information is displayed on said display (46), when an operator pushes a specific help button (47) at said man machine interface (25).

### Claim 31 (depends on 1)

Method for operating a control unit (22) as claimed in claim 1 to control a HVAC system (10), which comprises means (19) for cooling the air passing through said HVAC system (10), a multi-speed indoor fan (18), an exhaust fan (21) and a damper (D1, D2, D3) for controlling the inflow of outdoor air (OA) into the HVAC system (10), wherein said control unit (22) allows a service technician to manually operate said cooling means (19) and said exhaust fan (21), and to select the speed of the indoor fan (18) and the position of the damper (D1, D2, D3) for a certain temporary period for commissioning, maintenance or service.

### Claim 32 (depends on 1)

Method for operating a control unit (22) as claimed in claim 1, wherein an alarm is initiated by said control unit (22), when a failure and/or malfunctioning of the control is detected by said control unit (22).

### Claim 33 (depends on 32)

Method as claimed in claim 32, wherein an alarm is initiated by said control unit (22), when a sensor (32, 37) connected to said control unit (22) returns a signal value out of its normal working range, or when a sensor (32, . . . , 37), which should be connected to said control unit (22), is not detected.

### Claim 34 (depends on 33)

Method as claimed in claim 33, wherein the control strategy of the HVAC system (10) is changed by said control unit (22) when a sensor (32, . . . , 37), which should be connected to said control unit (22), is not detected, according to the following table:
*Economizing is enabled @ RAH <55% rH/disabled @ RAH >65% rH
whereby OAT is an outdoor air temperature sensor (32), OAH is an outdoor air humidity sensor (33), RAT is a return air temperature sensor (35) and RAH is a return air humidity sensor (36).

### Claim 35 (depends on 32)

Method as claimed in claim 32, wherein an alarm is initiated and an associated function is disabled by said control unit (22), when a device (18, 21, 37), which should be connected to said control unit (22), is no longer detected by said control unit (22).

### Claim 36 (depends on 35)

Method as claimed in claim 35, wherein said device is one of a CO2 sensor (37), exhaust fan (21) and indoor fan (18).

### Claim 37 (depends on 25)

Method as claimed in claim 25, wherein, before normal operation, said control unit (22) is run through test and verification sequences to support and ensure compliance with certain standards and/or regulations.

### Claim 38 (depends on 37)

Method as claimed in claim 37, wherein a built-in test routine is run in a step-bystep operation with visual verification, and wherein during said test mode a damper actuator (17) of the economizer (EC) is commanded to temporarily run with a higher speed in order to save time in completing the test.

### Claim 39 (depends on 37)

Method as claimed in claim 37, wherein in the process of running an acceptance test, if the damper rotation is intentionally limited, said control unit (22) will adapt to the intended angle to provide full resolution.

### Claim 40 (depends on 25)

Method as claimed in claim 25, wherein said control unit (22) counts and maintains for statistical purposes certain parameters of its operation including: hours of operation in demand controlled ventilation mode (DCV), of compressors (C1, C2), in economizing mode, in integrated cooling mode, in ventilation mode, in heating mode, and unoccupied.

### Claim 41 (depends on 25)

Method as claimed in claim 25, wherein, to enable a service technician to identify a potential problem, alarms are stored within said control unit (22).

### Claim 42 (depends on 25)

Method as claimed in claim 25, wherein, in case of a blackout or brownout, said control unit (22) shuts down compressors (C1, C2) of said cooling means (19) and prevents compressors (C1, C2) of said cooling means (19) from being enabled.

### Claim 43 (depends on 42)

Method as claimed in claim 42, wherein, when after a blackout or brownout power is restored to normal levels, or when an initial power-up takes place, said compressors (C1, C2) are enabled in a random fashion to prevent multiple compressors in multiple rooftop units (RTU) from starting at the same time in order to prevent a power drain that could initiate a blackout or brownout situation.

### Claim 44 (depends on 25)

Method as claimed in claim 25, wherein operation of compressors (C1, C2) of said cooling means (19) is adapted to optimize energy consumption and at the same time increase comfort and lifetime of the components.

### Claim 45 (depends on 44)

Method as claimed in claim 44, wherein the cooling means (19) and compressors (C1, C2) are protected by a minimum on/off time, of more than 10 sec, preferably of 3 min, or more.

### Claim 46 (depends on 44)

Method as claimed in claim 44, wherein the number of on/off cycles per hour of the cooling means (19) and compressors (C1, C2) is limited.

### Claim 47 (depends on 44)

Method as claimed in claim 44, wherein said cooling means is a cooling device (19) and a special temperature threshold is determined to deny or enable operation of said cooling device (19).

### Claim 48 (depends on 44)

Method as claimed in claim 44, wherein said cooling means (19) is a cooling device (19), and wherein said control unit (22) at an initial cooling call from a thermostat (31) will first try to satisfy said cooling call with reduced cooling power, and delay the activation of full cooling power.

### Claim 49 (depends on 25)

Method as claimed in claim 25, wherein an exhaust fan (21) is provided in said HVAC system (10), and wherein the operation of said exhaust fan is stabilized by a logic combination of: a minimum exhaust fan on and off time, adjusting a supply air temperature setpoint, choosing a gradient of supply air temperature change, adjusting damper to maintain supply air respectively mixed air setpoint, and making an adaptive change of an on/off threshold for said exhaust fan (21).

### Claim 50 (depends on 25)

Method as claimed in claim 25, wherein an indoor fan (18) and an exhaust fan (21) are provided in said HVAC system (10), and wherein a threshold of said exhaust fan (21) is adjusted dependent on the speed of said indoor fan (18).

### Claim 51 (depends on 25)

Method as claimed in claim 25, wherein operation of compressors (C1, C2) of said cooling means (19) is monitored by looking at a drop in Supply or Mixed Air temperature (SAT/MAT), which is to be expected after a compressor (C1, C2) is switched on, and generating an alarm, if such an expected temperature drop is missed.

### Claim 52 (depends on 25)

Method as claimed in claim 25, wherein an internal voltage is monitored, and a brownout is detected based on a long-term and momentary development of said internal voltage, and wherein said internal voltage is derived from the voltage and/or frequency of a primary or secondary power supply, especially by detecting a voltage drop of a predetermined percentage.