Honeywell T7425A1005 / VFF20-75P65
- Type: NTC 20 kΩ (25 °C), immersion
- Measurement range: -20 → +140 °C
- Accuracy: ±0.4 °C (0 → +100 °C)
- Probe length + IP: 75 mm; head IP65
Applications
Honeywell T7425A1005 is the primary immersion sensor for Honeywell HVAC control schemes. Used for: heating flow/return temperature, DHW supply temperature after the heat exchanger, DH return-line measurement, boiler-room outlet monitoring. The 75 mm probe suits DN 20–50 pipework. Compatible with Honeywell Excel 5000, Excel 500, Centraline Falcon and other platforms reading the Honeywell NTC 20 kΩ standard. Delivery across the EU.
Technical specifications
| Parameter | Value |
|---|---|
| Code | T7425A1005 (VFF20-75P65) |
| Model | Honeywell VFF20-75P65 |
| Sensor type | NTC thermistor, 20 kΩ (25 °C) |
| Mounting | Immersion in a pocket (G ½") |
| Probe length | 75 mm |
| Probe diameter | Ø 6 mm |
| Measurement range | -20 → +140 °C |
| Accuracy | ±0.4 °C (0 → +100 °C), ±0.8 °C over the remainder |
| Time constant | ≈ 20 s (in pocket) / ≈ 8 s (direct in liquid) |
| Probe material | Stainless steel AISI 316 |
| Wiring | 2-wire, terminals in the sensor head |
| Protection class | IP65 (head) |
| Compatibility | Honeywell Excel 5000, Excel 500, Centraline Falcon and other NTC 20 kΩ controllers |
Designer note
T7425A1005 uses NTC 20 kΩ (Honeywell's standard — NOT 10 kΩ Ouman, NOT 1.8 kΩ Schneider EGU). Verify controller documentation before replacing a sensor. The 75 mm probe suits DN 20–50 pipework — pocket active length should be 55–65 mm so the tip sits at the flow centre. Fill the pocket with heat-transfer paste or silicone oil.
When to choose T7425A1005
- Accurate water-temperature reading on Honeywell Excel / Centraline systems
- DN 20 → DN 50 pipework with an installed pocket
- Heating, DHW or DH return-line points
- When a higher IP65 rating is required (protection against moist environments)
- Compatibility: Honeywell Excel 5000, Excel 500, Centraline Falcon and other Honeywell NTC 20 kΩ controllers. Not compatible with Ouman (NTC 10 kΩ), Danfoss ECL (PT1000), Schneider TAC (NTC 1.8 kΩ).
B2B delivery and logistics
- Delivery across the EU (from warehouse in Vilnius, LT)
- Competitive B2B pricing for projects and bulk orders
- 30-day payment terms for companies (per contract)
- Free technical consultation on pocket / probe-length selection
Official Honeywell catalog: buildings.honeywell.com
FAQ
Does T7425A1005 fit Ouman or Danfoss controllers?
No. T7425A1005 uses NTC 20 kΩ. Ouman reads NTC 10 kΩ, Danfoss ECL reads PT1000, Schneider TAC reads NTC 1.8 kΩ. These standards are not interchangeable — verify the controller documentation first.
Resistance at 60 °C?
An NTC 20 kΩ element reads roughly 5.3 kΩ at 60 °C; ~25 kΩ at 20 °C; 20 kΩ at 25 °C (nominal). A multimeter check confirms operation.
Is the pocket ordered separately?
Standard orders require the pocket to be ordered separately — a Honeywell or third-party G ½" pocket with 55–65 mm active length. Contact us — we will match it to your pipe diameter and pressure class.
How to extend the cable?
Standard 2-wire line up to 100 m of unshielded 2×1.5 mm² cable. Shielded twisted pair for longer runs or high-EMI environments. NTC signals are tolerant of cable resistance and remain undistorted.
Difference between VFF20 and VFF10?
The number before P65 encodes probe length; VFF20 = 75 mm, VFF10 = 100 mm on some variants. P65 refers to the IP65 rating. Choose based on pipe diameter and ambient conditions.
