Choosing an HVAC temperature sensor starts with the measurement point and controller input, not with a generic accuracy or temperature-range claim. A platinum resistance temperature detector (RTD), such as a PT100 when specified by the system designer, must match the controller configuration, installation and process conditions. Use this checklist to define the assembly for an HVAC OEM project.
1. Define the HVAC measurement point
Specify what the sensor is intended to measure: for example, air in a duct, room air, or a fluid in a pipe or equipment circuit. Confirm the control sequence and the representative location with the HVAC designer. Duct location, airflow, nearby heat sources, mixing and mounting can affect what temperature the sensor actually sees. Follow the equipment maker’s installation instructions for the specific application.
2. Match the sensor to the controller input
Confirm whether the control input is designed for a PT100 RTD and identify the required resistance curve, connection method and input configuration. Check whether the system uses a two-, three- or four-wire arrangement and how it handles lead resistance. Do not assume that PT100, PT1000, NTC and thermocouple inputs are interchangeable. The controller manual and specified sensor datasheet define the compatible combination.
Where an industrial platinum RTD is specified, use the applicable edition of IEC 60751 as the reference for the resistance-temperature relationship and requirements. This standard reference does not establish that an arbitrary probe is suitable for a particular HVAC controller or installation.
3. Specify mounting and probe construction
Describe the mounting interface and drawing dimensions, including insertion depth, probe diameter, thread or pocket arrangement, cable exit and connector. State whether the measurement is made in air or through a thermowell or other protective fitting. Material, sealing and mechanical requirements must be selected for the actual exposure and verified against the supplier’s documented assembly configuration.
4. Check wiring, cable routing and environment
Provide the wiring diagram, lead length, connector and routing constraints. Identify moisture, vibration, cleaning, condensation or other environmental exposures relevant to the point. Confirm cable and connection details against the controller and sensor documentation; do not rely on generic claims that all PT100 probes have the same response, durability or operating limits.
5. Validate the installed measurement channel
Check the configured controller input and wiring, then compare the installed reading with a suitable reference under representative operating conditions. Include the sensor, wiring, input electronics, mounting and control logic in the review. A platinum element’s nominal tolerance alone does not determine the performance of the complete HVAC measurement channel.
HVAC RTD sensor RFQ checklist
- HVAC equipment and controller model, input type and configuration
- Measurement point, medium, operating conditions and control purpose
- Specified RTD type/curve and two-, three- or four-wire connection
- Probe drawing, mounting interface, insertion depth and required materials
- Cable, connector, routing and environmental exposure
- Required inspection records, traceability and validation method
- Expected quantity, sample plan and target project schedule
Attach the controller wiring diagram and installation drawing when requesting a review. This helps the sensor supplier assess mechanical and electrical fit without assuming an unverified operating range or performance value.
Related RTD resources
See the RTD temperature sensor range and our RTD sensor types guide for additional selection context. For project-specific evaluation, request an OEM sensor review with your HVAC controller details and mounting drawing.
Technical references
- IEC 60751:2022 — industrial platinum resistance thermometers and platinum temperature sensors.
- Siemens application guide for ventilation and air-conditioning plants — HVAC control context for supply-air temperature measurement and sensor placement.
