G.A.S Intelligent Humidity / VPD Controller - Automatic Humidity Control Based on Real Plant Science
Best for: growers who want their humidifier or dehumidifier switched automatically based on Vapour Pressure Deficit rather than a fixed humidity percentage.
Our thoughts
Most humidity controllers just hold a fixed relative humidity percentage. This one calculates VPD from both temperature and humidity together, which is a genuinely more accurate way to judge how "thirsty" the air actually is for your plants at their current growth stage. If you've been guessing at humidity targets rather than working them out, this takes the guesswork away.
The G.A.S Intelligent Humidity Controller manages the humidity in your grow room automatically, switching connected humidifiers on and off to hold the right level for faster growth and healthier plants. It works on the principle of Vapour Pressure Deficit (VPD) - the combination of air temperature and humidity that determines how readily plants can transpire moisture through their leaves.
Rather than requiring you to work out and set a humidity percentage yourself, the controller uses a 3-in-1 probe to sense temperature, humidity and light level, then calculates the correct humidity target for your current conditions and growth stage automatically. It offers four operating modes, letting you choose between straightforward humidity control or full VPD-based control, and between a constant target or separate day and night settings that shift automatically with your light cycle.
How it compares
VPD-based control puts this ahead of basic percentage-based humidity controllers.
- Versus a standard humidity controller that just holds a fixed relative humidity: this unit calculates VPD from both temperature and humidity together, which more accurately reflects what your plants are actually experiencing.
- Versus TrolMaster's VPD-capable modules: TrolMaster's ecosystem offers app connectivity and multi-zone expansion at a higher price; this controller keeps VPD-based control local and self-contained.
- Versus AC Infinity's Controller 69 Pro: AC Infinity's unit adds Bluetooth/WiFi app control across multiple devices; the G.A.S controller is a dedicated, simpler humidity/VPD unit at a lower price point.
You're getting genuine VPD calculation, not just a relabelled humidity percentage dial.
Usage guidance
Setup covers both simple and advanced use cases.
Probe placement
Position the 3-in-1 probe centrally within the canopy area for accurate temperature, humidity and light readings.
Choosing a mode
Select humidity control or VPD control, then choose between a constant target or separate day/night settings depending on how much your room's conditions shift with the light cycle.
Connecting your humidifier
Wire in your mains-powered humidifier or dehumidifier to the controller's output; it will switch the device on and off automatically to hold your chosen target.
Technical specifications
- Control type: Automatic humidity / VPD controller
- Manufacturer: Global Air Supplies (G.A.S UK)
- Sensor: 3-in-1 probe (temperature, humidity, light)
- Operating modes: 4 (humidity or VPD, constant or day/night)
- Scheduling: Separate day and night targets available
- Output: Switches connected humidifier/dehumidifier on and off automatically
Who this is for
- Growers who want humidity managed by VPD rather than a fixed percentage guess
- Anyone running a mains-powered humidifier or dehumidifier who wants it automated
- Growers adjusting targets across different growth stages who want day/night differentiation built in
Best suited to growers who already understand, or want to start using, VPD as their environmental target rather than relative humidity alone.
Our take
This is a proper step up from basic humidity control - calculating VPD from real sensor data rather than asking you to guess at a percentage. For anyone serious about dialling in their environment, that distinction matters.
Worth picking up if you want equipment you can rely on to take the guesswork out of humidity targets.
