Issue
Technicians need accurate resistance‑to‑temperature references for legacy and current sensors during BMS upgrades or service. Field users typically know the system in use rather than the thermistor bead type, which makes it difficult to pick the correct resistance table.
Product Line
Andover Continuum, EcoStruxure Building Operation, Field Devices, Satchwell MicroNet, Satchwell Sigma, TAC IA Series, TAC INET, TAC Vista
Environment
- HVAC and BMS installations using NTC thermistors or RTDs
- Retrofit projects where existing field sensors are retained
- EBO controllers and I/O modules that require correct thermistor curve selection for accurate engineering units
Cause
If the controller is configured with a thermistor curve that does not match the actual sensor element, the temperature reading will be offset or incorrect. Lack of documentation for legacy sensors or mixed‑vendor estates makes curve identification difficult.
Note:
In EBO, the thermistor selection in the IO module or controller does not represent the thermistor bead type, an example is the Continuum Type I in EBO, but the bead is a Type 3,. For further information regarding this see the KB article Thermistor type selection in EBO.
Resolution
Use the mapping guide below to start from the product range you are servicing, then identify the thermistor or RTD curve, and finally open the correct attachment/table to obtain R–T values.
Attachments available
- All sensors.pdf – multi‑vendor thermistor and RTD tables including 1.8K A1, 2.2K3A1, 3K3A1, 5K3A1, 10K3A1, 10K4A1, 20K6A, 30K6A1, 100K6A1, PT100A, PT1000A, Satchwell T‑range, DD/DR, DO.
- USSensorTypeG.pdf – complete R–T curve for US Sensor 10K “Curve G”
- Thermistor types‑tables.pdf – comparative tables for 2.2k, 3k, 10K Type II, Type III, Dale, US “G”, 20k, 100k, plus RTDs.
- Thermistortempresistchart.pdf – PreCon Type II, Type III, Type IV, Model 3 (10k), Model 42 (20k).
- RS‑03 NTC10K (3950) chart.pdf – generic NTC10K B=3950 curve.
- 1k Balco.pdf – 1 kΩ Balco RTD chart.
A. Product range to thermistor curve mapping
Schneider Electric legacy families
| System / Family | Typical sensor family in field | Thermistor or RTD curve to use | Open this table |
|---|---|---|---|
| Andover Continuum | ACC Temp, legacy room and duct sensors | 10K4A1 (NTC 10k class as listed; reference points: 25 °C (77 °F), 40 °C (104 °F)) | All sensors.pdf → 10K4A1 table |
| TAC Vista | Vista 1.8K A1 sensors | 1.8K A1 curve (reference points often shown around 25 °C (77 °F), 50 °C (122 °F)) | All sensors.pdf → 1.8K A1 table |
| TAC INET | INET 10K2A1 (Dale) | 10K Dale / Type 9 class (e.g., 25 °C (77 °F) = 10 kΩ) | All sensors.pdf → 10K2A1 table; Thermistor types‑tables.pdf for Dale column |
| TAC I/A Series (MNL/MNB) | Commonly paired with US Sensor “Type G” elements with 11k ± 0.1% 1/8 watt resistor wired in parallel with the sensor |
US Sensor 10K “Curve G” (e.g., 25 °C (77 °F) = 10 kΩ (5,238Ω with shunt ; 40 °C (104 °F) ≈ 5.592 kΩ (3,707Ω with shunt) |
TS‑57XX‑85X / TS‑67XX‑85X 10K Thermistor with 11K Shunt Resistance Table |
| Satchwell MicroNet or Sigma | Satchwell T‑range, DD/DR, DO sensors | Use the dataset for the specific Satchwell family (e.g., tables include 0 °C (32 °F), 25 °C (77 °F), 50 °C (122 °F) points) | All sensors.pdf → Satchwell T‑range, DD/DR, DO tables |
| Field Devices | TC900 RS03 | Generic NTC10K elements (use 25 °C (77 °F) = 10 kΩ; 0 °C (32 °F) ≈ 31.77 kΩ) | RS-03 NTC10K (3950) chart.pdf |
Other common manufacturer mappings
| Vendor / Product | Thermistor curve | Open this table |
|---|---|---|
| Honeywell Aquatrol, Trend, Ambiflex, York | 10K3A1 (e.g., 25 °C (77 °F) = 10 kΩ; 50 °C (122 °F) ≈ 3.601 kΩ) | All sensors.pdf → 10K3A1 table |
| Allerton | 3K3A1 (check typical points like 25 °C (77 °F), 50 °C (122 °F)) | All sensors.pdf → 3K3A1 table |
| Ambiflex 2040 | 2.2K3A1 | All sensors.pdf → 2.2K3A1 table |
| Honeywell 20K6A | NTC 20k (e.g., 0 °C (32 °F) ≈ 70.204 kΩ; 25 °C (77 °F) = 20 kΩ) | All sensors.pdf → 20K6A table |
| Drayton DC1000 / DC1100 | 30K6A1 (e.g., 0 °C (32 °F) ≈ 105.305 kΩ; 25 °C (77 °F) = 30 kΩ) | All sensors.pdf → 30K6A1 table |
| Schlumberger (air) | 5K3A1 | All sensors.pdf → 5K3A1 table |
| Schlumberger (immersion) | 100K6A1 | All sensors.pdf → 100K6A1 table |
Generic curves frequently seen on retrofits
| Curve | When you might see it | Open this table |
|---|---|---|
| NTC 10k, B=3950 | Generic NTC10K elements in third‑party or OEM sensors (use 25 °C (77 °F) = 10 kΩ; 0 °C (32 °F) ≈ 31.77 kΩ as spot checks) | RS‑03 NTC10K (3950) chart.pdf |
| US Sensor 10K “Curve G” | Many commercial 10k sensors and I/A Series integrations (25 °C (77 °F) = 10 kΩ; 40 °C (104 °F) ≈ 5.592 kΩ) | USSensorTypeG.pdf |
| PreCon 10k (Model 3) | PreCon‑sourced 10k elements at 77 °F (25 °C (77 °F) = 10 kΩ) | Thermistortempresistchart.pdf → Model 3 [Thermistor...esistchart | PDF] |
| PreCon 20k (Model 42) | PreCon‑sourced 20k elements (25 °C (77 °F) = 20 kΩ) | Thermistortempresistchart.pdf → Model 42 |
| PreCon Type II / Type III / Type IV | 2252 Ω, 3k, and 100k families (77 °F reference; common checks at 25 °C (77 °F)) | Thermistortempresistchart.pdf |
| 1 kΩ Balco RTD | Legacy RTD elements in some estates (e.g., 20 °C (68 °F) ≈ 997 Ω) | 1k Balco.pdf |
RTD sensors
| RTD | Open this table |
|---|---|
| PT100A | All sensors.pdf → PT100A table |
| PT1000A (common checks at 0 °C (32 °F), 25 °C (77 °F)) | All sensors.pdf → PT1000A table |
B. Quick verification points for spot‑checks
Use these values to sanity‑check field readings after selecting the correct curve.
- US Sensor 10K “Curve G”: 25 °C (77 °F) = 10,000 Ω; 40 °C (104 °F) ≈ 5,592 Ω.
- 10K4A1: 25 °C (77 °F) = 10,000 Ω; 40 °C (104 °F) ≈ 5,594 Ω.
- 10K3A1: 25 °C (77 °F) = 10,000 Ω; 50 °C (122 °F) ≈ 3,601 Ω.
- 20K6A: 0 °C (32 °F) ≈ 70,204 Ω; 25 °C (77 °F) = 20,000 Ω.
- 30K6A1: 0 °C (32 °F) ≈ 105,305 Ω; 25 °C (77 °F) = 30,000 Ω.
- PT100A: 0 °C (32 °F) ≈ 100.8 Ω.
- 1 kΩ Balco: 20 °C (68 °F) ≈ 997 Ω.
- NTC 10k B=3950: 25 °C (77 °F) = 10,000 Ω; 0 °C (32 °F) ≈ 31.77 kΩ.
- PreCon Model 3 (10k): 25 °C (77 °F) = 10,000 Ω.
C. Technician workflow
- Identify the system on site and open the corresponding row in the mapping table.
- Note the thermistor or RTD curve indicated.
- Open the attachment listed and use the R–T table to configure the controller and validate readings.
