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Thermostats / Sensors

Thermostats / Sensors

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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
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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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    Siemens 540-995 10K Ohm (Apogee Tec) Ntc Thermst

    Siemens Building Technology

    MSRP: $54.73
    Now: $42.29
    Siemens 540-995 10K Ohm (Apogee Tec) Ntc Thermst  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order Requirements
    MSRP: $54.73
    Now: $42.29
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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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    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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    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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    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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    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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    Siemens 540-652A Digital Thermostat W/Fan Switch

    Siemens Building Technology

    MSRP: $1,140.84
    Now: $881.56
    Siemens 540-652A Digital Thermostat W/Fan Switch  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order Requirements
    MSRP: $1,140.84
    Now: $881.56
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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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    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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    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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    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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    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
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    Siemens 536-774-25 2.5" Imm Sensor, 20-70F

    Siemens Building Technology

    MSRP: $171.57
    Now: $132.57
    Siemens 536-774-25 2.5" Imm Sensor, 20-70F  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order Requirements
    MSRP: $171.57
    Now: $132.57
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    MSRP: $171.57
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    Siemens 536-768 O/A Temp Sens Platinum -58/122F

    Siemens Building Technology

    MSRP: $184.22
    Now: $142.35
    Siemens 536-768 O/A Temp Sens Platinum -58/122F  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order Requirements
    MSRP: $184.22
    Now: $142.35
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    MSRP: $184.22
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    Siemens 536-767-60 Imm Temp Sensor Pat.30/250, 6"

    Siemens

    MSRP: $139.80
    Now: $105.91
    Siemens 536-767-60 Imm Temp Sensor Pat.30/250, 6"  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order Requirements...
    MSRP: $139.80
    Now: $105.91
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    Siemens 536-767-40 Imm Temp Sensor Plat.30/250, 4"

    Siemens Building Technology

    MSRP: $147.30
    Now: $113.82
    Siemens 536-767-40 Imm Temp Sensor Plat.30/250, 4"  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order...
    MSRP: $147.30
    Now: $113.82
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    MSRP: $147.30
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    Siemens 536-767-25 Imm Temp Sensor Plat.30/250

    Siemens Building Technology

    MSRP: $171.52
    Now: $132.54
    Siemens 536-767-25 Imm Temp Sensor Plat.30/250  FurnacePartSource.com Commitment Item Typically Ships Within the Same Business Day Brand-New Genuine Parts - EverytimeNo Minimum Order Requirements
    MSRP: $171.52
    Now: $132.54
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    MSRP: $171.52
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Thermostats and Sensors for HVAC Systems 

HVAC thermostats and furnace sensors are essential for regulating system performance, energy efficiency, and safety. These components monitor conditions such as temperature, pressure, and flame status, ensuring furnaces, air conditioners, and heat pumps operate correctly. Furnace Part Source offers a wide range of OEM furnace sensors and thermostats for both residential and commercial applications. 

Types of HVAC Thermostats 

  • Non-Programmable Thermostats – Manual models that maintain a set temperature until adjusted.
  • Programmable Thermostats – Digital controls with scheduling features to reduce energy usage during off
  • Smart Thermostats – Wi-Fi connected, app-enabled devices with advanced features like occupancy detection and zoning compatibility. 

Compatibility and Replacement 

Selecting the correct OEM thermostat or sensor ensures accurate readings and reliable operation. Always verify part numbers, voltage requirements, and system configuration (single-stage, multi-stage, or heat pump) before replacing components. 

Maintenance and Upgrades 

Faulty sensors can cause misreadings, wasted energy, or system shutdowns. Replacing worn parts or upgrading to energy-efficient thermostats restores system reliability, reduces utility costs, and extends equipment life. 

Wide Selection from Furnace Part Source 

With access to over 500,000 parts from 300+ manufacturers, Furnace Part Source provides the right solution for any repair or upgrade. From thermistors to programmable thermostats, our catalog includes components designed for both residential and commercial HVAC systems. 

Frequently Asked Questions 

What types of thermostats are available for HVAC systems? 

Options include non-programmable, programmable, and smart thermostats, each offering different levels of control and energy efficiency. 

How do I know if my furnace sensor needs replacement?

Signs include frequent system shutdowns, inaccurate temperature readings, or ignition failures.  

Why should I use OEM furnace sensors? 

OEM parts ensure proper fit, compatibility, and performance, reducing the risk of system malfunctions.

What is the difference between a thermocouple and a flame sensor? 

Thermocouples generate voltage to detect a pilot flame, while modern flame sensors use electronic signals to confirm burner ignition. 

Can upgrading to a smart thermostat improve efficiency?

Yes. Smart thermostats allow remote control, scheduling, and advanced optimization, often reducing energy costs.