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Furnace & HVAC Sensors

Furnace & HVAC Sensors

Shop furnace and HVAC replacement sensors for residential, commercial, and industrial heating and cooling systems. Furnace Part Source carries temperature sensors, immersion sensors, humidity sensors, flow sensors, and safety probes from Honeywell, Siemens, Veris Industries, MAMAC Systems, System Sensor, and other leading brands.

Use the product list below to find the correct sensor by part number, sensor type, or equipment model. Always confirm resistance value, output signal, mounting style, and equipment model before ordering to help avoid compatibility issues.

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    Siemens 7MF15654BB005EA1 Sensor, Liquid/Gas, 4-20Ma, 0-15#

    Siemens Building Technology

    MSRP: $444.10
    Now: $343.17
    Siemens 7MF15654BB005EA1 Sensor, Liquid/Gas, 4-20Ma, 0-15#  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order...
    MSRP: $444.10
    Now: $343.17
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    MSRP: $444.10
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    Siemens 544-578 Temp Sensor O/Air -40/240F

    Siemens Building Technology

    MSRP: $66.61
    Now: $51.47
    Siemens 544-578 Temp Sensor O/Air -40/240F  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order Requirements
    MSRP: $66.61
    Now: $51.47
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    Siemens 544-577-40 -40/240F Immersion Avg Sensor

    Siemens Building Technology

    MSRP: $130.17
    Now: $100.58
    Siemens 544-577-40 -40/240F Immersion Avg Sensor  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order Requirements
    MSRP: $130.17
    Now: $100.58
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    MSRP: $130.17
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    Siemens 544-577-25 Imm Sensor -40/240 1000Ohm Plat

    Siemens Building Technology

    MSRP: $124.48
    Now: $96.19
    Siemens 544-577-25 Imm Sensor -40/240 1000Ohm Plat  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order...
    MSRP: $124.48
    Now: $96.19
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    MSRP: $124.48
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    Siemens 544-562-40 4" 32/212F Immersion Sensor

    Siemens

    MSRP: $139.67
    Now: $105.81
    Siemens 544-562-40 4" 32/212F Immersion Sensor  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order Requirements
    MSRP: $139.67
    Now: $105.81
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    MSRP: $139.67
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    Siemens 544-483A Temp Sensor Repair Kit

    Siemens

    MSRP: $58.00
    Now: $43.94
    Siemens 544-483A Temp Sensor Repair Kit  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order Requirements
    MSRP: $58.00
    Now: $43.94
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    MSRP: $58.00
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    Siemens 544-343-24 D/Av Sensor, 24"Prb, Rtd, 20-120F

    Siemens Building Technology

    MSRP: $136.82
    Now: $105.72
    Siemens 544-343-24 D/Av Sensor, 24"Prb, Rtd, 20-120F  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order...
    MSRP: $136.82
    Now: $105.72
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    MSRP: $136.82
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    Siemens 544-339-18 D/Pt Temp. Sensor, Rtd, -40/240F

    Siemens Building Technology

    MSRP: $64.83
    Now: $50.09
    Siemens 544-339-18 D/Pt Temp. Sensor, Rtd, -40/240F  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order...
    MSRP: $64.83
    Now: $50.09
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    MSRP: $64.83
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    Siemens 544-089 Surface Mount Pipe Sensor

    Siemens

    MSRP: $59.32
    Now: $44.94
    Siemens 544-089 Surface Mount Pipe Sensor  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order Requirements
    MSRP: $59.32
    Now: $44.94
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    MSRP: $59.32
    Now: $44.94
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    Siemens 540-680CB White Temp Sen W/Set Pt & O/R Cel

    Siemens Building Technology

    MSRP: $247.48
    Now: $187.49
    Siemens 540-680CB White Temp Sen W/Set Pt & O/R Cel  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order...
    MSRP: $247.48
    Now: $187.49
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    MSRP: $247.48
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    Siemens 540-680CA Beige Temp Sen W/Set Pt & O/R Cel

    Siemens

    MSRP: $708.71
    Now: $536.90
    Siemens 540-680CA Beige Temp Sen W/Set Pt & O/R Cel  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order...
    MSRP: $708.71
    Now: $536.90
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    MSRP: $708.71
    Now: $536.90
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    Siemens 540-670B Tec Room Sensor, W/Stpt, Ovride

    Siemens Building Technology

    MSRP: $659.74
    Now: $509.80
    Siemens 540-670B Tec Room Sensor, W/Stpt, Ovride   FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - Everytime No Minimum Order...
    MSRP: $659.74
    Now: $509.80
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    MSRP: $659.74
    Now: $509.80
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    Siemens 540-670A Beige Rm Temp Sensor W/Set Pt & O/R

    Siemens Building Technology

    MSRP: $628.32
    Now: $485.52
    Siemens 540-670A Beige Rm Temp Sensor W/Set Pt & O/R  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order...
    MSRP: $628.32
    Now: $485.52
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    MSRP: $628.32
    Now: $485.52
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    Siemens 540-660A Room Sensor, Beige, Tec

    Siemens Building Technology

    MSRP: $369.75
    Now: $285.71
    Siemens 540-660A Room Sensor, Beige, Tec   FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - Everytime No Minimum Order...
    MSRP: $369.75
    Now: $285.71
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    MSRP: $369.75
    Now: $285.71
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    Siemens 540-520A Room Temp Sensor Flush Mount

    Siemens Building Technology

    MSRP: $130.38
    Now: $100.75
    Siemens 540-520A Room Temp Sensor Flush Mount  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order Requirements
    MSRP: $130.38
    Now: $100.75
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    MSRP: $130.38
    Now: $100.75
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    Siemens 540-246-72 6'Flex Avg Sensor Ntc 100K Ohm Type2

    Siemens

    MSRP: $98.60
    Now: $74.70
    Siemens 540-246-72 6'Flex Avg Sensor Ntc 100K Ohm Type2  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order...
    MSRP: $98.60
    Now: $74.70
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    MSRP: $98.60
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    Siemens 540-245-36 Flex Avg Sens Ntc 100K Ohm 36"P

    Siemens

    MSRP: $97.07
    Now: $73.54
    Siemens 540-245-36 Flex Avg Sens Ntc 100K Ohm 36"P  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order...
    MSRP: $97.07
    Now: $73.54
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    MSRP: $97.07
    Now: $73.54
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    Siemens 540-244-18 Rigid Avg Temp Sens 18"

    Siemens Building Technology

    MSRP: $98.92
    Now: $76.44
    Siemens 540-244-18 Rigid Avg Temp Sens 18"  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order Requirements
    MSRP: $98.92
    Now: $76.44
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    MSRP: $98.92
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    Siemens 536-811 100K Ohm Duct Temp Sensor

    Siemens Building Technology

    MSRP: $25.08
    Now: $19.38
    Siemens 536-811 100K Ohm Duct Temp Sensor   FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - Everytime No Minimum Order...
    MSRP: $25.08
    Now: $19.38
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    MSRP: $25.08
    Now: $19.38
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    Siemens 536-777-25 Imm Sensor 100Kohm Therm

    Siemens

    MSRP: $96.69
    Now: $73.25
    Siemens 536-777-25 Imm Sensor 100Kohm Therm  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order Requirements
    MSRP: $96.69
    Now: $73.25
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    MSRP: $96.69
    Now: $73.25
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Furnace & HVAC Sensors

Furnace and HVAC sensors monitor temperature, airflow, flame presence, humidity, and other conditions that keep a heating or cooling system operating safely and efficiently. When a sensor fails or reads inaccurately, it can cause lockouts, poor comfort control, or unsafe operation.

Furnace Part Source carries a wide range of replacement sensors, including duct and immersion temperature sensors, outside air sensors, humidity sensors, flow sensors, and safety-related probes for residential, commercial, and industrial HVAC equipment.

Common Sensors We Carry

Common replacement sensors include:

  • Duct and immersion temperature sensors for supply, return, and water temperature readings.
  • Outside air temperature and humidity sensors for outdoor reset and economizer control.
  • Flow sensors for airflow and duct pressure monitoring.
  • Low-level and safety probe sensors for boiler and water-level protection.
  • Gas and smoke detection sensors for combustible gas and safety monitoring.

How to Find the Right Sensor

Before ordering, confirm the sensor's resistance value (such as 10K or 20K ohm), output signal type, mounting style, and the equipment model it is used with. Sensors that look similar can have different resistance curves or output signals, so matching by part number is the safest approach.

For best fit, compare:

  • Original sensor part number
  • Resistance value or output signal type
  • Sensor style, such as duct, immersion, outside air, or surface-mount
  • Equipment model and control system

Sensors From Leading HVAC Brands

Our catalog includes sensors from Honeywell, Siemens Building Technology, Veris Industries, MAMAC Systems, System Sensor, Dwyer Instruments, Aaon, Kele, and other major manufacturers, covering both standard replacement sensors and specialized industrial sensing equipment.

Need Help Matching a Sensor?

Not sure which sensor you need? Use the part number, resistance value, and control system information from your equipment to narrow the search, or contact Furnace Part Source for help identifying the correct replacement.

HVAC Sensor FAQs

What types of sensors does an HVAC system use?

HVAC systems commonly use temperature sensors, humidity sensors, flow sensors, flame sensors, and safety probes to monitor conditions and support proper system control.

How do I know what resistance value my sensor needs?

Check the original sensor's part number or the equipment documentation, which typically lists the resistance value, such as 10K or 20K ohm, required for compatibility.

Can a bad sensor cause my system to shut down?

Yes. A failed or inaccurate sensor reading can trigger lockouts or prevent proper operation, particularly for safety-related sensors like low-water or flame sensors.

Are furnace sensors and thermostat sensors the same?

No. Furnace and HVAC sensors typically monitor internal equipment conditions, while thermostat sensors read room temperature for comfort control. Always confirm the specific application before ordering.