Indoor air quality and economizer control methods and controllers

• US 20060150644A1
• Filed: 01/10/2005
• Published: 07/13/2006
• Est. Priority Date: 01/10/2005
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Wruck, Richard A.
• Granted Patent: US 7,434,413 B2
• Time in Patent Office: Days
• US Class Current: 62/126
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/62 characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
• CPC Class Codes: F24F 11/74 for controlling air flow rate or air velocity
• CPC Class Codes: F24F 2011/0006 using low temperature external supply air to assist cooling
• CPC Class Codes: F24F 2110/12 of the outside air
• CPC Class Codes: F24F 2110/50 Air quality properties
• CPC Class Codes: F24F 2110/70 Carbon dioxide
• CPC Class Codes: F24F 2110/72 Carbon monoxide
• CPC Class Codes: F24F 2120/10 Occupancy
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

Supervisory controllers, and methods, for use in a coordinated IAQ and economizer system. Various control objectives are defined and met. Some illustrative control objectives include economizer control, sequencing of economizer free cooling with compressor driven cooling, indoor air quality and FAV aims, demand ventilation settings, system protection from low temperatures, and smoke, supervisory and fault tolerance commands. The controller may be self configuring. A tiered fault tolerant controller is also provided. An illustrative controller is configured to determine whether various system sensors and devices are operational. The illustrative controller is also configured to perform a first method when all system sensors and/or devices are functioning, and at least a second method in response to sensor or device failures. The supervisory controller may include integrated economizer control, or may be configured as a separate controller. Supervisory controllers configured for use with specialized controllers are also illustrated.

Claims

1. A controller for an HVAC system, the controller having inputs and outputs for receiving information from and sending commands to components of an HVAC system including one or more sensors, a fan, cooling equipment, and fresh air ventilation components, the controller configured to perform the following steps:

determining whether a component or sensor of the HVAC system is operational;

if so, performing a first HVAC method;

or

if not, performing a second HVAC method.

2. The controller of claim 1 wherein the controller comprises a microcontroller including readable media containing an instruction set for performing the recited steps.

3. The controller of claim 1 wherein:

the first HVAC method uses a dual enthalpy economizer mode of operation;

the second HVAC method uses a single enthalpy economizer mode of operation.

4. The controller of claim 1 wherein:

the first HVAC method uses a differential economizer mode of operation; and

the second HVAC method uses setpoint economizer mode of operation.

5. The controller of claim 1 wherein:

the controller comprises an economizer module;

during the first HVAC method the economizer module is enabled; and

during the second HVAC method the economizer module is disabled.

6. An HVAC supervisory controller for use in an HVAC system including one or more sensors, a fan, heating equipment, cooling equipment, and fresh air ventilation components, the supervisory controller configured to perform the following steps:

determine whether sensors and equipment of the HVAC system are operational;

if so, direct the HVAC system to operation in a first mode;

if not, direct the HVAC system to operation in a second mode.

7. The HVAC supervisory controller of claim 6 wherein the first mode is an economizer mode, and the second mode is not an economizer mode.

8. The HVAC supervisory controller of claim 6 wherein the HVAC system includes an economizer controller, wherein the HVAC supervisory controller is configured to enable the HVAC system to operate in accordance with instructions from the economizer controller when in the first mode, and to disable operation of the HVAC system in accordance with instructions from the economizer controller when in the second mode.

9. An HVAC controller for use in an HVAC system, the HVAC system including:

a fan, cooling equipment, and fresh air ventilation components;

first means for sensing enthalpy disposed to sense system return air enthalpy; and

second means for sensing enthalpy disposed to sense outside air enthalpy;

the HVAC controller configured to receive signals from both the first and second means for sensing enthalpy, the HVAC controller adapted to perform the following steps;

determine whether the first and second means for sensing enthalpy are functioning;

if both the first and the second means for sensing enthalpy are functioning, operating the HVAC system using an economizer mode having a differential enthalpy economizer decision process; and

if the first means for sensing enthalpy is not functioning, operating the HVAC system using a second mode that does not include a differential enthalpy economizer decision process.

10. The controller of claim 9 wherein the HVAC system further includes a dry bulb sensor disposed to measure outdoor temperature, wherein the HVAC controller is further adapted to perform the following steps:

determine whether the dry bulb sensor is functioning;

if the second means for sensing enthalpy is not functioning;

if the dry bulb sensor is functioning, operating the HVAC system using an economizer mode having an outside air dry bulb decision process.

11. The controller of claim 10 wherein the HVAC system controller is further adapted such that, if the second means for sensing enthalpy is functioning:

if the dry bulb sensor is not functioning, operating the HVAC system using an economizer mode not having an outside air dry bulb override decision process;

or

if the dry bulb sensor is functioning, operating the HVAC system using an economizer mode including an outside air dry bulb override decision process.

12. The controller of claim 9 wherein the HVAC system further comprises an economizer controller, the controller further comprising inputs and outputs configured for coupling with the economizer controller.

13. A method of operating an HVAC system comprising:

determining whether an enthalpy sensor disposed for sensing return air enthalpy is operational;

determining whether an enthalpy sensor disposed for sensing outdoor air enthalpy is operational;

if both sensors are operational, operating the HVAC system using an economizer mode using dual enthalpy analysis; and

,

if the sensor disposed for sensing outdoor air enthalpy is operational and the sensor disposed for sensing return air enthalpy is not operational, operating the HVAC system using an economizer mode using a single enthalpy analysis.

14. The method of claim 13 further comprising:

determining whether a dry bulb sensor disposed for sensing outdoor temperature is operational;

if the sensor disposed for sensing outdoor temperature is not operational and the sensor disposed for sensing outdoor air enthalpy is operational, disabling an outside air temperature override from any economizer mode in use.

15. The method of claim 14 further comprising, if the sensor disposed for sensing outdoor air enthalpy is not operational and the sensor disposed for sensing outdoor temperature is operational, operating the HVAC system using an economizer mode using an outdoor temperature, but not enthalpy, process.

16. The method of claim 13 further comprising:

determining whether a dry bulb sensor disposed for sensing outdoor temperature is operational; and

if the sensor disposed for sensing outdoor air enthalpy is not operational and the sensor disposed for sensing outdoor temperature is operational, operating the HVAC system using an economizer mode using an outdoor temperature, but not enthalpy, process.

17. A system for controlling an HVAC system including number of sensors and HVAC operation devices including a fan, dampers, and a temperature modification apparatus, the system comprising:

a first controller configured for providing a specialized HVAC system method;

a second controller having inputs and outputs for coupling to the first controller, the sensors, and the HVAC devices, the second controller adapted to perform the steps of;

observing which sensors are functioning;

determining whether the specialized HVAC system method is appropriate; and

controlling interactions between the first controller and the HVAC devices.

18. The system of claim 17 wherein the specialized HVAC system method is an economizer control process.

19. The system of claim 17 wherein the specialized HVAC system method is an FAV control method.

20. The system of claim 17 wherein:

the HVAC system includes smoke and fire detection equipment;

the second controller has inputs for the smoke and fire detection equipment; and

the second controller is configured to control portions of the HVAC system in response to signals from the smoke and fire detection equipment to override the specialized HVAC system method.