Method for detecting a non-closing water heater main gas valve
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Solution Overview
Problem
Conventional water heaters face challenges in detecting when the main gas valve does not completely close, leading to potential inefficiencies and false temperature readings due to sediment or flocculants impairing valve operation.
Innovation Solution
A system comprising a water tank, main gas burner, pilot gas burner, water temperature sensor, and thermopile, with a controller that monitors the thermopile signal and water temperature to detect stable states and toggle the main gas valve to verify closure, using a predetermined change in thermopile signal to determine if the valve is stuck open.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the main gas valve is used to control gas flow without additional detection mechanisms, then the device complexity is reduced, but the reliability of detecting non-closure conditions deteriorates
Solution Approach 1:
The system uses the thermopile signal as feedback to monitor the state of the main gas valve. By continuously comparing the thermopile signal against expected ranges for valve-closed and valve-open conditions, the system can detect non-closure states without requiring additional sensors or complex detection mechanisms.
Solution Approach 2:
The existing thermopile, which is already part of the ignition system, is repurposed to serve a dual function: detecting the presence of a main burner flame and monitoring the closure state of the main gas valve. This eliminates the need for separate detection devices.
2Measurement precision
If conventional temperature monitoring is used without thermopile signal analysis, then the device complexity is lower, but the measurement precision of gas valve closure status deteriorates
Solution Approach 1:
The thermopile is utilized for multiple purposes: detecting the ignition state of the main burner and monitoring the closure status of the main gas valve. This multi-functional use of an existing component enables precise valve status detection without adding dedicated measurement devices.
3Reliability
If the controller continuously monitors thermopile signal for non-closure conditions, then the reliability of valve closure detection is improved, but the loss of time for normal operation increases
Solution Approach 1:
The controller performs non-closure detection at specific intervals or under specific conditions (e.g., when the valve is commanded to close), rather than continuously monitoring. This periodic checking approach maintains detection reliability while minimizing the time overhead during normal water heater operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively detects and addresses non-closure conditions of the main gas valve, ensuring accurate temperature control and preventing inefficiencies by determining if the valve is fully closed, thus enhancing the operational reliability and efficiency of the water heater.
Implementation Method 1
A thermopile has a first portion that is positioned proximate a pilot flame that is produced by the pilot gas burner and a second portion that is positioned proximate a main burner flame that is produced by the main gas burner. The thermopile outputs a thermopile signal that is representative of a temperature difference between the first portion of the thermopile and the second portion of the thermopile.
Implementation Method 2
A pilot gas burner is disposed proximate the main gas burner such that the pilot gas burner is positioned to ignite the main gas burner.
Data Source
AI summary
A water heater may be configured to detect a possible main gas valve non-closure condition in which the sensed water temperature continues to rise while a thermopile signal reaches a stable state. When the possible main gas valve non-closure condition is detected, the controller may be configured to toggle the main gas valve ON and determine whether the thermopile signal from the thermopile changes from the stable state or not by at least a predetermined amount.