Field-Adjustable PICCV Assembly for Faster HVAC Flow Balancing
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Solution Overview
Problem
Current HVAC systems with variable flow require time-consuming and costly balancing, especially when changes occur due to remodeling or varying loads, leading to inefficient operation and increased energy costs, as control valves must be constantly adjusted to maintain optimal flow rates despite pressure fluctuations.
Innovation Solution
A field adjustable control valve assembly with a mechanism that includes an adjustment screw to set the maximum open flow rate, allowing for easy adjustment using a readily available hand tool, which eliminates the need for complex recalibration and reduces delays in valve operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional balancing valves are installed and manual balancing procedures are performed, then flow rates can be adjusted during installation, but the system requires time-consuming and costly balancing procedures with highly skilled technicians, and the system cannot be easily rebalanced when remodeling or load changes occur
Solution Approach 1:
The patent replaces manual mechanical balancing procedures with an automated electronic system. The electronic actuator receives control signals and automatically adjusts valve positioning based on feedback from flow sensors, eliminating the need for manual intervention by skilled technicians and reducing balancing time from hours to minutes.
Solution Approach 2:
The system implements closed-loop feedback control where flow sensors continuously monitor actual flow rates and compare them against target values. The controller automatically adjusts valve positions based on this feedback, enabling precise flow rate control without manual intervention and allowing easy rebalancing when system conditions change.
2Reliability
If control valves are sized for design conditions with high differential pressure, then the valve authority is sufficient at design conditions, but when the system operates at average load conditions with reduced flow and increased differential pressure, the valve authority decreases and the modulating valve acts only as on/off
Solution Approach 1:
The patent implements dynamic valve authority compensation where the system automatically adjusts valve positioning and control parameters based on real-time differential pressure measurements. When differential pressure increases at part-load conditions, the controller compensates by adjusting the valve stem position to maintain adequate valve authority and modulating capability across the full range of operating conditions.
Solution Approach 2:
The system changes operational parameters dynamically by adjusting valve position, control signal scaling, and setpoint values based on measured differential pressure and flow conditions. This allows the valve to maintain optimal performance and modulating capability whether operating at design conditions with high flow or at average load conditions with reduced flow and increased differential pressure.
3Adaptability or versatility
If balancing valves are installed at each control valve location, then flow can be adjusted during initial balancing, but any remodeling or change in building use requires complete system rebalancing
Solution Approach 1:
The patent replaces complex manual balancing valve assemblies with automated electronic control systems. The electronic actuators with integrated flow sensors and controllers provide automatic flow rate control, eliminating the need for manual balancing valves and their associated complex adjustment mechanisms. This simplifies the overall system while improving adaptability to remodeling.
Solution Approach 2:
The electronic control system serves multiple functions: it controls flow rates during operation, performs automatic balancing, adapts to remodeling changes, and provides diagnostic capabilities. This multi-functional approach replaces the single-function manual balancing valve, reducing device complexity while enhancing system adaptability to various building configurations and uses.
Data Source
AI summary
A flow setting assembly is provided to permit field adjustment of an electronically actuated flow control valve, particularly a pressure independent characterized control valve (PICCV). In a preferred form, flow can be field adjusted by using a hex tool. Therefore, the maximum flow can be increased or decreased within the valve's adjustable flow range. As with all high close-off valves that employ a ball in their design, the ball passes well into the seat when rotated to the actuator's zero-degree position. Therefore, there is an amount of travel within the first degrees of ball rotation that passes back over this seat. The flow setting assembly eliminates this excess rotation (12°) resulting in a closed position that is offset to improve control resolution and system accuracy. This offset continues to allow the high close-off rating of 200 PSI. MFT actuators electronically adjust to and maintain the 2-10 Volt control signal at the reduced angle, as well as the 100 second running time and feedback signal. On floating point (−3) actuators, the running time is constant but dependent on the overall angle of rotation.