A Damper Control System for Preventing Reverse Airflow Through the Exhaust Air Damper of Variable-Air-Volume Air-Handling Units

Abstract Faults in air-based heating, ventilation, and air conditioning (HVAC) systems lead to energy waste and discomfort. While the emphasis of fault detection and diagnostic (FDD) research has been on hard faults in actuators, sensors, and equipment, faults arising from human errors account for a significant portion of faults occurring in HVAC systems. In this paper, human errors occurring in air handling units (AHUs) and variable air volume (VAV) thermal zones during design, construction, and operation phases are identified through a review of the literature. Then, the faults are divided into six main categories. Based on case studies investigating these faults, the impact of each fault category on occupant comfort, energy consumption, and equipment life is discussed. The authors provide recommendations to minimize human errors in AHUs and VAV zones throughout the building life cycle.

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Study of Constant Airflow Rate and Constant Room Pressure Control Systems for Physical Containment Laboratories

Journal of the IEST ◽

10.17764/jiet.1.31.1.g8u27p67t23242rw ◽

1988 ◽

Vol 31 (1) ◽

pp. 56-61

Author(s):

Atsushi Takahashi ◽

Takao Okada

Keyword(s):

Control System ◽

Control Systems ◽

Static Pressure ◽

Pressure Control ◽

Volume Control ◽

Airflow Rate ◽

Processing Unit ◽

Variable Air Volume ◽

Central Processing ◽

Air Volume

This study discusses various control systems that can keep the room pressure and supply/exhaust airflow rate at constant levels in "other rooms" of a highly airtight containment facility when the supply/exhaust airflow is shut off in one of the rooms for decontamination purposes. This study has shown that the constant air volume control system (CAV) allows hysteresis to occur at small differentials on the performance curve of the static pressure differentials and that this hysteresis can cause wide fluctuations in room pressure. In contrast, the variable air volume, central processing unit (VAV-CPU) control system can maintain both airflow rates and room pressures. Each room pressure was controllable to the set level, with an error of less than ±0.5 mmH2O even during transient distur bances. This control system limited fluctuations in the airflow to and from each room to 5 percent during the transient responses. This control system also allows power savings in the operation of supply/exhaust fans, because of the reduced airflow rate and the static pressure of the fans, and is considered to be an excellent control system.

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Performance evaluation of damper control settings for operation of multiple-zone variable air volume reheat system in different building applications and climate types

Building Simulation ◽

10.1007/s12273-017-0353-4 ◽

2017 ◽

Vol 10 (5) ◽

pp. 687-696 ◽

Cited By ~ 2

Author(s):

Esmail M. Saber

Keyword(s):

Performance Evaluation ◽

Variable Air Volume ◽

Air Volume ◽

Damper Control

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Variable Air Volume System Application in Museums

ASME 2007 Energy Sustainability Conference ◽

10.1115/es2007-36058 ◽

2007 ◽

Author(s):

Zhan Wang ◽

Bin Zheng ◽

Wenlong Xu ◽

Gang Wang ◽

Mingsheng Liu

Keyword(s):

Energy Consumption ◽

System Control ◽

Variable Air Volume ◽

Heating And Cooling ◽

Air Volume ◽

Variable Frequency Drives ◽

Air Handling Units ◽

Simultaneous Heating ◽

Simultaneous Heating And Cooling ◽

Cooling Loads

Relative humidity and temperature control is key in museums, galleries, libraries and archives. Normally constant volume (CV) air handling units (AHUs) with reheat coils are applied in these buildings. Setting a low supply air temperature limits the highest humidity level; however, reheat coils have to be used to maintain space temperature due to constant supply airflow. As a result, simultaneous heating and cooling exists with excessive energy consumption. It is well known that variable air volume (VAV) technologies can reduce simultaneous heating and cooling as well as fan power. This paper presents the detail VAV system retrofit for the existing CV system, control sequence development and system performance evaluation in a museum facility at Omaha, Nebraska. Variable Frequency Drives (VFDs) were installed for the supply fan on the AHUs. Space humidity and temperature, heating and cooling energy consumption, and fan power were measured. The measurements showed that the space humidity and temperature was maintained within the required range under VAV operation while the reheat consumption was reduced by up to 85% and the fan power consumption was reduced by 90% under partial cooling loads.

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