Lochinvar & A.O. Smith 100074281 Output Thermistor
The Lochinvar & A.O. Smith 100074281 Output Thermistor is a critical NTC temperature sensor engineered for precise thermal monitoring in high-efficiency tankless water heaters and commercial boilers. As a genuine OEM replacement part, this thermistor (equivalent to EKK2T) provides real-time resistance feedback to the control board, allowing the system to modulate gas and water valves with surgical accuracy. This ensures consistent output water temperature while preventing heat exchanger scaling or thermal runaway. Designed for heavy-duty HVACR environments, it features robust moisture-resistant leads and a calibrated sensor head that maintains stability across a wide temperature range—typically 10.3 k? at 68°F (20°C).
Replacing a fouled or drifted thermistor is essential for resolving common error codes like 311 or 321, which often indicate an open or shorted sensor circuit. For senior technicians, this part is a "first-look" component when a unit fails to reach setpoint or exhibits erratic firing cycles. Proper installation involves inspecting the O-ring seal and ensuring the wiring harness is free of tension or corrosion to maintain signal integrity.
- Universal Compatibility: Fits an extensive range of models including TD2U, TM50, TK3, TH3, and TK540P series units.
- High Sensitivity: Delivers rapid response times to minor temperature fluctuations for optimal energy efficiency.
- Direct OEM Fit: Ensures 100% compatibility with original factory control board logistics and mounting points.
- System Protection: Acts as a primary feedback loop to safeguard the heat exchanger from overheat conditions.
Common Questions
What resistance should I see when testing the 100074281?
At room temperature (approx. 77°F), you should typically measure around 8.5 k?. Always refer to the manufacturer’s specific resistance-to-temperature chart in the service manual to verify accuracy across the operating curve.
Can I use a generic thermistor instead of the 100074281?
Using non-OEM sensors is not recommended. Professional control boards are calibrated to the specific thermal curve of the 100074281; an incorrect curve can lead to inaccurate water temperatures or persistent lockout codes.
Will this fix an E10 or 321 error code?
Yes, these codes often point toward a failure in the output thermistor circuit. Before replacing, verify that the connector pins are clean and the black lead wires are not pinched or broken.
This item is not eligible for free shipping.
Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.
Original: $12.89
-65%$12.89
$4.51Lochinvar & A.O. Smith 100074281 Output Thermistor
The Lochinvar & A.O. Smith 100074281 Output Thermistor is a critical NTC temperature sensor engineered for precise thermal monitoring in high-efficiency tankless water heaters and commercial boilers. As a genuine OEM replacement part, this thermistor (equivalent to EKK2T) provides real-time resistance feedback to the control board, allowing the system to modulate gas and water valves with surgical accuracy. This ensures consistent output water temperature while preventing heat exchanger scaling or thermal runaway. Designed for heavy-duty HVACR environments, it features robust moisture-resistant leads and a calibrated sensor head that maintains stability across a wide temperature range—typically 10.3 k? at 68°F (20°C).
Replacing a fouled or drifted thermistor is essential for resolving common error codes like 311 or 321, which often indicate an open or shorted sensor circuit. For senior technicians, this part is a "first-look" component when a unit fails to reach setpoint or exhibits erratic firing cycles. Proper installation involves inspecting the O-ring seal and ensuring the wiring harness is free of tension or corrosion to maintain signal integrity.
- Universal Compatibility: Fits an extensive range of models including TD2U, TM50, TK3, TH3, and TK540P series units.
- High Sensitivity: Delivers rapid response times to minor temperature fluctuations for optimal energy efficiency.
- Direct OEM Fit: Ensures 100% compatibility with original factory control board logistics and mounting points.
- System Protection: Acts as a primary feedback loop to safeguard the heat exchanger from overheat conditions.
Common Questions
What resistance should I see when testing the 100074281?
At room temperature (approx. 77°F), you should typically measure around 8.5 k?. Always refer to the manufacturer’s specific resistance-to-temperature chart in the service manual to verify accuracy across the operating curve.
Can I use a generic thermistor instead of the 100074281?
Using non-OEM sensors is not recommended. Professional control boards are calibrated to the specific thermal curve of the 100074281; an incorrect curve can lead to inaccurate water temperatures or persistent lockout codes.
Will this fix an E10 or 321 error code?
Yes, these codes often point toward a failure in the output thermistor circuit. Before replacing, verify that the connector pins are clean and the black lead wires are not pinched or broken.
This item is not eligible for free shipping.
Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.
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Description
The Lochinvar & A.O. Smith 100074281 Output Thermistor is a critical NTC temperature sensor engineered for precise thermal monitoring in high-efficiency tankless water heaters and commercial boilers. As a genuine OEM replacement part, this thermistor (equivalent to EKK2T) provides real-time resistance feedback to the control board, allowing the system to modulate gas and water valves with surgical accuracy. This ensures consistent output water temperature while preventing heat exchanger scaling or thermal runaway. Designed for heavy-duty HVACR environments, it features robust moisture-resistant leads and a calibrated sensor head that maintains stability across a wide temperature range—typically 10.3 k? at 68°F (20°C).
Replacing a fouled or drifted thermistor is essential for resolving common error codes like 311 or 321, which often indicate an open or shorted sensor circuit. For senior technicians, this part is a "first-look" component when a unit fails to reach setpoint or exhibits erratic firing cycles. Proper installation involves inspecting the O-ring seal and ensuring the wiring harness is free of tension or corrosion to maintain signal integrity.
- Universal Compatibility: Fits an extensive range of models including TD2U, TM50, TK3, TH3, and TK540P series units.
- High Sensitivity: Delivers rapid response times to minor temperature fluctuations for optimal energy efficiency.
- Direct OEM Fit: Ensures 100% compatibility with original factory control board logistics and mounting points.
- System Protection: Acts as a primary feedback loop to safeguard the heat exchanger from overheat conditions.
Common Questions
What resistance should I see when testing the 100074281?
At room temperature (approx. 77°F), you should typically measure around 8.5 k?. Always refer to the manufacturer’s specific resistance-to-temperature chart in the service manual to verify accuracy across the operating curve.
Can I use a generic thermistor instead of the 100074281?
Using non-OEM sensors is not recommended. Professional control boards are calibrated to the specific thermal curve of the 100074281; an incorrect curve can lead to inaccurate water temperatures or persistent lockout codes.
Will this fix an E10 or 321 error code?
Yes, these codes often point toward a failure in the output thermistor circuit. Before replacing, verify that the connector pins are clean and the black lead wires are not pinched or broken.
This item is not eligible for free shipping.
Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.
