Gas Furnace Pressure Transducer Self-Check Using Pressure Switch Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Pressure transducers in HVAC systems are less reliable and accurate compared to pressure switches, and failures can lead to operational issues such as noise and CO generation, necessitating a method to detect and address failures effectively.
Innovation Solution
A controller system that includes a pressure transducer, pressure switch, and processor to determine the status of the pressure transducer as reliable, unreliable, or questionable based on received signals, and stop the draft inducer motor operation when the transducer is deemed unreliable, utilizing both the pressure transducer and pressure switch signals for self-checks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure transducer is used to monitor inducer pressure in an HVAC system, then measurement precision is improved, but reliability deteriorates
Solution Approach 1:
The system continuously monitors the pressure transducer output and compares it against expected pressure ranges during different operational states (inducer off, inducer running, burners on, burners off). When the transducer reading falls outside the expected range, the controller generates a diagnostic code indicating potential transducer failure, allowing the system to provide feedback about transducer health status.
Solution Approach 2:
The system performs preliminary checks of the pressure transducer by monitoring its output during specific operational conditions before actual combustion occurs. By checking the transducer reading when the inducer is running but burners are not yet lit, the system can detect potential failures before they lead to unsafe conditions.
2Reliability
If pressure transducer status monitoring is implemented, then reliability is improved, but device complexity increases
Solution Approach 1:
The existing controller is enhanced to perform multiple functions: it continues to control the HVAC system operation while simultaneously monitoring pressure transducer readings, comparing them against expected ranges, and generating diagnostic codes. This multi-functionality approach avoids adding separate dedicated monitoring hardware.
Solution Approach 2:
The system monitors its own components using the existing controller and available sensors. The pressure transducer is checked against expected operational parameters without requiring external testing equipment or separate monitoring systems, allowing the HVAC system to self-diagnose transducer health.
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
The system effectively detects and responds to pressure transducer failures, preventing operational issues by ensuring the reliability of the pressure transducer, thereby maintaining system performance and safety.
Implementation Method 1
The pressure transducer is positioned to sense a pressure within the conduit and output signals proportional to the sensed pressure
Implementation Method 2
The pressure switch is positioned to sense the pressure within the conduit and has a first state and a second state. The pressure switch is configured to be in the first state when the sensed pressure is below a predetermined pressure and to switch to the second state when the sensed pressure reaches or exceeds the predetermined pressure
Data Source
AI summary
A method of controlling a gas furnace system includes controlling a motor of a draft inducer to increase a speed of the motor in response to a call for heat, receiving pressure signals output by a pressure transducer, receiving signals indicating whether a pressure switch is in a first state or a second state, and determining a first status of the pressure transducer as reliable, unreliable, or questionable at a first time based on the received pressure signals from the pressure transducer, the signals indicating whether the pressure switch is in the first state or the second state, and a first status of the motor of the draft inducer at the first time. Operation of the motor of the draft inducer is stopped when the first status of the pressure transducer indicates that the pressure transducer is unreliable.