Modulating Boiler Control Using Thermostat On-Time Feedback
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Solution Overview
Problem
Existing boiler systems face inefficiencies due to reliance on outdoor air sensors, which can provide erroneous measurements, fail to account for non-temperature related heat sources, and are limited in reducing energy consumption, especially in systems without feedback mechanisms.
Innovation Solution
A modulating boiler system that calculates energy input based on the moving average of the thermostat's on-time, eliminating the need for ambient air sensors and using exponential moving averages to adjust boiler energy input, thereby optimizing boiler efficiency and reducing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If outdoor reset systems are used to adjust boiler set point based on outdoor temperature, then energy consumption is reduced, but measurement precision deteriorates due to erroneous sensor readings and limitations
Solution Approach 1:
The system uses feedback from indoor thermostat operation (on-time measurements) to continuously adjust the boiler set point. Instead of relying on outdoor sensors, the system measures how long the thermostat is on and uses this feedback to determine the appropriate boiler temperature, eliminating measurement errors from outdoor sensors while maintaining energy efficiency.
Solution Approach 2:
The system introduces an intermediary measurement approach by using the thermostat's on-time as a proxy indicator for heating requirements. Rather than directly measuring outdoor temperature with a sensor, the system uses the thermostat operation duration as an indirect but more reliable indicator of actual heating needs, thereby avoiding sensor measurement errors.
2Use of energy by moving object
If outdoor sensors are installed to enable outdoor reset control, then device complexity increases due to installation and calibration requirements, but this enables energy reduction
Solution Approach 1:
The system performs self-service by using existing indoor thermostat data to determine heating requirements. No external outdoor sensors are needed - the system leverages the already-present thermostat and its operational data to automatically adjust boiler set points, eliminating the complexity of sensor installation, positioning, and calibration while achieving energy reduction.
Solution Approach 2:
The system extracts the essential control function from the outdoor sensor approach by removing the outdoor sensor entirely. Instead of using outdoor temperature measurements, the system extracts heating requirement information directly from indoor thermostat operation patterns, thereby eliminating the complex sensing infrastructure while maintaining control functionality.
3Reliability
If boiler set point is constrained to ensure minimum water temperature for comfort, then comfort is maintained, but energy efficiency deteriorates
Solution Approach 1:
The system applies dynamics by making the boiler set point adjustable and responsive rather than fixed. The set point dynamically adapts based on measured thermostat on-time, allowing the system to lower temperatures when heating demand is low (improving efficiency) while automatically raising them when demand increases (maintaining comfort). This dynamic adjustment resolves the contradiction between fixed comfort constraints and energy efficiency.
Solution Approach 2:
The system changes the temperature parameter dynamically based on actual heating demand as indicated by thermostat on-time. Rather than maintaining a constant minimum set point, the system adjusts the set point parameter up or down according to measured conditions, thereby reducing energy input when possible while ensuring comfort is maintained when heating demand requires it.
Data Source
AI summary
A modulating boiler system for heating a structure including a controller, a boiler operatively connected to the controller, and a thermostat operatively connected to the controller and boiler. The controller assesses a level of thermostat activity over a predetermined measuring period and adjusts the boiler in response to the level of activity to increase the boiler's efficiency.