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Lochinvar & A.O. Smith 100093749 K Thermostat 1.5" Shank FG 42.75K LP

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Special Price $266.61 Regular Price $295.94
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SKU
100093749
The Lochinvar & A.O. Smith 100093749 K Thermostat is a high quality and long lasting thermostat with 1.5 inch shank for use in water heaters that uses liquid propane gas. It has a heating capacity of 42.75K BTU and is designed for controlling temperature of HVAC systems for effective water heating. This thermostat make it easy to maintain a specific temperature throughout the year without straining more energy and enhances the durability of the water heater. This is in common use in Lochinvar and A.O. Smith water heaters as it serves as thermal cutoffs and pressure n relief to avoid over heating and or high pressure. This thermostat makes users more comfortable and saves them money on energy.
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HVAC Controls & Electrical, Control & Sensing Devices
Manufacturer:
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Specifications

  • Type: Thermostat
  • Shank Size: 1.5"
  • Fuel Type: LP
  • Flow Rate: 42.75K

Product Overview:
Water temperature in a propane-fired storage water heater is regulated by a thermostat that responds to changes in the stored water temperature and controls the burner operation. The Lochinvar & A.O. Smith 100093749 K Thermostat is an OEM replacement control designed for liquid propane water-heater applications. Its temperature-responsive mechanism regulates the gas control operation to maintain the selected water temperature. The component is specified for a 42,750 BTU/hr application and uses a 1.5-inch shank configuration.

Thermostat Temperature Regulation:
The thermostat responds to changes in water temperature through its sensing mechanism. As the stored water cools, the control allows the gas burner to operate and restore the water temperature. When the selected temperature is reached, the thermostat changes the control state to stop further heating. This repeated operation regulates the water-heating cycle and helps maintain the selected temperature during normal use.

Gas Control and Burner Operation:
The thermostat works as part of the water heater's gas control assembly, coordinating burner operation according to the sensed water temperature. Its control action determines when the burner receives the signal to operate or stop heating. The thermostat must match the water heater's fuel type, burner capacity, and mechanical shank arrangement to maintain the intended control sequence. This model is specified for liquid propane equipment rather than being a universal gas thermostat.

Replacement Guidelines:
Replace the thermostat if the water heater fails to maintain the selected temperature, the burner does not respond correctly to temperature changes, or the control operates inconsistently. Before ordering, verify the water heater model and serial number, liquid propane fuel configuration, 1.5-inch shank length, and 42,750 BTU/hr application. Check the gas control assembly and associated connections for other possible causes of malfunction. Gas-control servicing should be performed by a qualified technician, followed by the required gas-leak and operational safety checks.

Common Failure Symptoms:

  • Water temperature does not reach the selected setting
  • Burner fails to operate when the stored water cools
  • Burner continues heating after the selected temperature is reached
  • Water temperature fluctuates during normal operation
  • Gas control does not respond correctly to thermostat demand

Equipment Compatibility:
The Lochinvar & A.O. Smith 100093749 K Thermostat is listed for 1.5-inch-shank, 42,750 BTU/hr liquid propane water-heater applications. Available model-level parts cross-references include American Water Heaters FG12240T403NOV, FG12150T403NO, FG12140S403NOV, and FG2F5040T3NOV. The manufacturer's historical parts catalog also identifies legacy part number 6910554 for 100093749. Confirm the complete model and serial number, fuel type, and original thermostat part number before ordering.

Technical Specifications:
Brand: Lochinvar & A.O. Smith
Part Number/SKU: 100093749
Product Type: K Thermostat
Shank Length: 1.5 inches
Construction Designation: FG
Gas Type: Liquid Propane (LP)

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Product Questions (7)
Customer Questions
What maintenance is required for the Lochinvar & A.O. Smith 100093749 K Thermostat?

Inspect electrical connections and thermostat calibration regularly to ensure accurate temperature control. Clean dust and debris from contacts to prevent signal interference. Check for gas or LP system compatibility and tighten fittings during routine servicing.

What are common issues with the Lochinvar & A.O. Smith 100093749 K Thermostat?

  • Thermostat miscalibration causing incorrect temperature readings.
  • Intermittent heating or failure to maintain setpoint.
  • Wiring or connection faults leading to no response.
  • Sensor degradation affecting accuracy.
  • Gas valve sticking or delayed ignition in LP systems.

What is the Lochinvar & A.O. Smith 100093749 K Thermostat used for?

It regulates water temperature in selected liquid propane water heaters by controlling the burner operation in response to changes in stored water temperature.

Which water heater models use the 100093749 thermostat?

Available parts cross-references identify American Water Heaters models FG12240T403NOV, FG12150T403NO, FG12140S403NOV, and FG2F5040T3NOV. Verify the complete model and serial number before selecting this replacement.

What are the shank length and heating capacity of the 100093749 thermostat?

It has a 1.5-inch shank and is specified for a 42,750 BTU/hr liquid propane water-heater application.

Is the 100093749 thermostat suitable for natural gas water heaters?

The documented part description specifies liquid propane (LP) service. Do not select it for a natural gas water heater unless the manufacturer's parts documentation explicitly confirms the application.

What should be checked before replacing the 100093749 thermostat?

Verify the original part number, water heater model and serial number, LP fuel configuration, shank length, and burner capacity. A qualified technician should also inspect the gas control assembly and complete the required safety checks.

Installation Steps

Step 1: Turn off electrical power and gas supply; check unit is completely shut down and cool.

Step 2: Remove access panel and disconnect existing old thermostat and capillary sensing bulb carefully.

Step 3: Install new thermostat with shank into mounting port and secure tightly to secure leaks.

Step 4: Route and position sensing bulb properly in designated location for accurate temperature response.

Step 5: Reconnect wiring or control leads and ensure all connections are firm and correctly seated.

Step 6: Restore power and gas, then test temperature control operation and confirm stable burner cycling and safe ignition.