Indoor air quality and economizer control methods and controllers

• US 7,434,413 B2
• Filed: 01/10/2005
• Issued: 10/14/2008
• Est. Priority Date: 01/10/2005
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Wruck, Richard A.
• Primary Examiner(s): Norman; Marc E
• Application Number:
  US11/032,460
• Publication Number:
  US 20060150644A1
• Time in Patent Office: 1,373 Days
• Field of Search: 165250-251, 62D/IG.22, 621/26, 621/86, 454/333, 236/49.3
• 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. An HVAC controller for use in an HVAC system, the HVAC system including:

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

a return air enthalpy sensor for sensing system return air enthalpy; and

an outside air enthalpy sensor for sensing outside air enthalpy;

a dry bulb sensor disposed to measure outside air temperature, wherein the dry bulb sensor is distinct from the outside air enthalpy sensor;

the HVAC controller configured to receive signals from the return air enthalpy sensor, the outside air enthalpy sensor and the dry bulb sensor, the HVAC controller adapted to perform the following steps;

determine whether the return air enthalpy sensor and the outside air enthalpy sensor are both functioning;

if both the return air enthalpy sensor and the outside air enthalpy sensor are both functioning, operating the HVAC system using an economizer mode having a differential enthalpy economizer decision process;

if the return air enthalpy sensor and the outside air enthalpy sensor are both not functioning, operating the HVAC system using a second mode that does not include a differential enthalpy economizer decision process;

determine whether the dry bulb sensor is functioning;

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

wherein the HVAC controller is further adapted such that, if the outside air enthalpy sensor 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.

2. The HVAC controller of claim 1 wherein the HVAC system further comprises an economizer controller, the HVAC controller further comprising inputs and outputs configured for coupling with the economizer controller.

3. 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;

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;

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

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.

4. The method of claim 3 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.

5. 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;

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; and

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

6. 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, the HVAC system including one or more sensors, a fan, a return air path controlled by a return air damper, an outside air path controlled by an outside air damper, and a mixed air path that includes air from the return air path and the outside air path, the controller configured to perform the following steps:

determining whether at least selected sensors of the HVAC system are operational;

if so, controlling the outside air damper and the return air damper using a first method; and

if not, controlling the outside air damper and the return air damper using a second method, wherein the first method is different from the second method;

wherein the at least selected sensors include a mixed air pressure sensor for sensing the pressure in the mixed air path.