The Titan Controls Tali 3-in-1 VPD Sensor measures temperature, humidity, and vapor pressure deficit (VPD) in a grow room. It reads temperature to ±0.5 °C, humidity to ±5% RH, and VPD to ±100 Pa. It runs on 6–24 VDC and reports the one number — VPD — that ties temperature and humidity together for plant transpiration. This page gives the maker’s published accuracy, electrical, and physical specs; explains what VPD is and why it matters; and is honest about what is not published. This listing is the 12-unit case (12/CS), per the maker’s case spec table.
What it is
The Tali 3-in-1 is a combined temperature / relative-humidity / VPD sensor for controlled-environment grow rooms. Rather than making you read RH and temperature separately and do the VPD math, it computes and reports VPD directly. The maker rates it for a 0–50 °C operating range, draws ≤ 800 mW maximum, and the sensor body measures 83 mm L × 55 mm W × 122 mm H. It ships with a 15 ft cable and 3-way connector plus an 8 ft cable and 3-way (T) connector, and the maker specifies it be wired on a Class 2 or Limited Energy circuit.
Specifications
| Temperature accuracy | ±0.5 °C |
|---|---|
| Relative-humidity accuracy | ±5% RH |
| VPD accuracy | ±100 Pa |
| Operating temperature range | 0–50 °C (32–122 °F) |
| Power supply | 6–24 VDC |
| Power draw | ≤ 800 mW maximum |
| Minimum environment airflow | 0.5–1 m/s |
| Sensor body dimensions | 83 mm L × 55 mm W × 122 mm H |
| Listed unit weight (retailer) | ~2.22 lb (retailer-listed; the maker does not publish a unit weight) |
| Case quantity | 12 units per case (12/CS), per the maker case spec table |
Why choose it
- It reports VPD directly. Instead of reading temperature and RH and converting, the sensor computes VPD to ±100 Pa so you can drive a controller on the number that actually governs transpiration.
- Tight temperature and humidity accuracy. ±0.5 °C and ±5% RH keep the derived VPD meaningful.
- Low-voltage, low-power. It runs on 6–24 VDC at ≤ 800 mW, wired on a Class 2 circuit, so it integrates with low-voltage controller inputs.
What VPD is and why it matters
Vapor pressure deficit is the difference between the amount of moisture the air can hold when saturated and the amount it actually holds — the drying power of the air. MSU Extension notes that VPD is a better guide to plant water status than relative humidity alone, because the same RH corresponds to very different drying power at different temperatures — for example 70% RH is about 0.55 kPa at 60 °F but about 1.45 kPa at 90 °F. That is why a combined sensor that reports VPD, rather than RH by itself, gives a more directly useful signal for managing transpiration, and why VPD-based control is used in controlled-environment rooms.
Where it fits
For other climate and environment products, browse the climate & environment category. General store policies are on the about page. A VPD sensor pairs with the humidity and airflow hardware it helps you control:
- Anden A100 Dehumidifier — a dehumidifier whose 0–10 V input a VPD-driven controller can drive.
- Ideal-Air 100 Pint Pro Series Dehumidifier — another humidity tool to balance against the VPD this sensor reports.
Frequently asked questions
What does it measure? Temperature (to ±0.5 °C), relative humidity (to ±5% RH), and VPD (to ±100 Pa).
How is it powered? On 6–24 VDC, drawing no more than 800 mW, on a Class 2 circuit.
How many units come in this listing? It is a 12-unit case (12/CS) per the maker case spec table.
Who this is for — and who should skip it
Suited: growers running VPD-based environmental control who want a single sensor that reports temperature, humidity, and VPD to ±100 Pa and integrates on a low-voltage circuit — and who can use the 12-unit case quantity.
Not for / its limits: it is a sensor, not a controller or an actuator — it reports conditions; it does not itself run a dehumidifier or fan. It needs at least 0.5–1 m/s of airflow at the sensor to read correctly, and it is wired on a Class 2 low-voltage circuit. The 12-unit case is aimed at multi-room or commercial buyers, not a single-sensor hobby purchase.
HELD (not stated because not sourced): the warranty term (retailer listings mention a one-year limited warranty; held per M-05, not reproduced here); the live retail price (the WooCommerce price field is the source of truth at deploy); shelf life; and any grow-stage-specific VPD target beyond what MSU Extension explicitly states. The unit weight (~2.22 lb) is retailer-listed, not a maker spec.
Ready to dial in VPD? Add to cart, or talk to a grower about integrating the sensor with your controller.
Sources
- Titan Controls — Tali 3-in-1 VPD Sensor sell sheet (HGC702000): voltage 6–24 VDC; power ≤ 800 mW; operating range 0–50 °C; temperature accuracy ±0.5 °C; RH accuracy ±5% RH; VPD accuracy ±100 Pa; minimum airflow 0.5–1 m/s; Class 2 circuit; included cables/connectors. Manufactured for Hawthorne / Titan Controls (titancontrols.net-linked PDF, retrieved 2026-07-07): https://scotts-hawthorne-public-prod.s3-us-west-2.amazonaws.com/PROD/documents/Documents/1000731208_HGC702000-01_TitanControls_3in1SensorVPD_SellSheet_221102aSD_(1)_(1).pdf
- Titan Controls — Tali 3-in-1 VPD Sensor instruction manual (HGC702000): sensor body dimension 83 mm L × 55 mm W × 122 mm H; power ≤ 0.8 W; 6–24 V DC; operating range 0–50 °C (titancontrols.net-linked PDF, retrieved 2026-07-07): https://scotts-hawthorne-public-prod.s3-us-west-2.amazonaws.com/PROD/documents/Documents/1000753588_HGC702000-01_LB18572_TitanControls_Tali3in1VPDSensor_Instructions_221117aSD_WEB.pdf
- Titan Controls — maker product page (titancontrols.net): EACH/CASE/PALLET spec table confirms case quantity = 12 units (12/CS). Note titancontrols.com is a parked domain; titancontrols.net is the live maker site (HTTP 200, retrieved 2026-07-07): https://www.titancontrols.net/shop/product/titan-controls-grow-room-sensors
- BGHydro — Titan Controls Tali 3-in-1 VPD Sensor listing: corroborates the maker specs and provides the observed unit weight (~2.22 lb), which the maker does not publish (retailer, retrieved 2026-07-07): https://www.bghydro.com/titan-controls-tali-3-in-1-vpd-sensor.html
- Wollaeger, H. & Runkle, E. — “Why should greenhouse growers pay attention to vapor-pressure deficit and not relative humidity?” (MSU Extension, 2015): VPD vs. RH, and that 70% RH is ~0.55 kPa at 60 °F vs. ~1.45 kPa at 90 °F (HTTP 200, retrieved 2026-07-07): https://www.canr.msu.edu/news/why_should_greenhouse_growers_pay_attention_to_vapor_pressure_deficit_and_n
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