Hydronic Heating PWM Control for Multi-Zone Auto-Balancing
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Solution Overview
Problem
Hydronic heating systems face challenges in effectively controlling diverse components from different vendors due to varying input signals and the need for manual balancing and initial programming, especially in retrofitted buildings.
Innovation Solution
A method and system that utilize pulse width modulated (PWM) control signals to interpret heat calls from different types of thermostats, enabling auto-balancing and self-learning without explicit set-point knowledge, allowing integration of various actuators and thermostats through digital signal conversion and averaging heat call durations and intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different types of thermostats and control valves from different vendors are used in a hydronic heating system, then the system can be retrofitted with existing components, but it becomes difficult to effectively control the system due to varying input signals and voltage levels
Solution Approach 1:
The patent introduces a central controller as an intermediary device that receives signals from various thermostat types through signal conditioning circuits. These circuits act as mediators that translate different thermostat signal formats into a unified digital representation, allowing the controller to process all inputs without direct complexity from each thermostat variant
Solution Approach 2:
The system changes the parameter representation of thermostat signals by converting analog voltage levels and different signal formats into standardized digital values. The controller samples and digitizes incoming signals, transforming diverse physical parameters into a common digital domain that simplifies subsequent processing and control decisions
2Manufacturing precision
If manual balancing and initial programming are required for hydronic heating systems, then precise control can be achieved, but the system installation time and complexity increase
Solution Approach 1:
The controller automatically performs balancing operations by monitoring thermostat signals and adjusting valve control outputs without requiring manual intervention. The system self-calibrates by observing heat call patterns and intervals, automatically determining optimal valve positions for each thermal zone, thereby eliminating the need for manual balancing procedures
Solution Approach 2:
The system implements continuous feedback loops where the controller monitors thermostat on/off signals and valve positions, then automatically adjusts control parameters based on observed system behavior. This closed-loop control enables the system to learn and adapt to actual thermal characteristics, achieving precise control without manual programming
3Manufacturing precision
If proportional controllers are used to control valve opening degrees, then precise flow control is achieved, but the system cannot utilize simple shutoff valves and requires more complex actuator control
Solution Approach 1:
The controller uses periodic on/off cycling of valves instead of continuous proportional control. By rapidly switching valves between fully open and fully closed positions according to calculated duty cycles, the system achieves effective flow modulation without requiring proportional valve actuation, simplifying actuator requirements while maintaining control precision
Solution Approach 2:
The patent replaces mechanical proportional valve control with electronic switching control. Instead of using mechanically controlled proportional valves that require complex position control mechanisms, the system uses electronic switches to control simple on/off valves, substituting mechanical complexity with electronic timing control
Data Source
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AI summary
The present disclosure relates to a method for controlling a hydronic heating system (10) comprising a plurality of thermal zones (20a-20c), in particular an underfloor heating system for a plurality of rooms. The method comprises monitoring a plurality of digital thermostat signals to obtain a timing of heat calls indicating a demand for heating in a corresponding thermal zone (20a-20c); determining respective duty cycles for a PWM control signal for each one of the plurality of thermal zones (20a-20c) based on the obtained timing of heat calls; and controlling a temperature of each thermal zone (20a-20c) by activating or deactivating a flow of liquid heating medium into the respective thermal zone (20a-20c) based on the determined duty cycle of the respective PWM control signal. The disclosure further relates to a control system for a hydronic heating system (10) and a computer program for implementing a corresponding control method.