G.A.S AC1 Thermostatic Fan Speed Controller - Simple Thermostatic Control for AC Fans
Best for: growers running a single AC extraction or intake fan up to 5 amps who want straightforward thermostatic speed control without EC compatibility.
Our thoughts
The AC1 is the no-fuss option if you're running a standard AC fan rather than an EC one. Unplug the sensor and it's a manual speed controller; plug it back in and it's thermostatic. That flexibility, plus built-in overload protection, makes it a sensible first controller for anyone not ready to commit to a full environmental system.
The G.A.S AC1 is a plug-in thermostatic fan speed controller for single-speed AC fans rated up to 5 amps (roughly 1150 watts). It works in two modes: unplug the temperature sensor and the fan runs continuously at your chosen minimum setting; plug the sensor back in and the AC1 switches to thermostatic mode, holding the fan at minimum "tick-over" speed until room temperature rises past your set point.
The digital sensor reads temperatures from 20°C to 30°C with 0.5°C accuracy, and ramps the fan up roughly 2°C above your set temperature to avoid it hunting on and off. You can set the minimum tick-over speed anywhere between 20% and 100% of full fan speed. It comes complete with a 2 metre cable and sensor, and includes built-in overload protection - if the controller itself gets too hot, it lets the fan run at full speed rather than cutting out, protecting your equipment while keeping the room from overheating.
How it compares
The AC1 sits at the entry point of G.A.S's AC fan controller range.
- Versus the Vortex Thermostatic Fan Speed Controller: Vortex units are rated to handle up to 1000W in a single AC channel; the AC1's 5A/1150W rating covers most single grow tent fans in the same bracket.
- Versus RAM's Varispeed controller: RAM's version is positioned as a budget single-fan option similarly to the AC1, while RAM's AIR-PRO II adds dual-fan control and pressure sensing at a higher price.
- Versus G.A.S's own EC1: the EC1 is built for EC fans specifically and needs no separate power supply; the AC1 covers standard AC fans and needs mains power itself.
For a single AC fan, the AC1 gives you genuine thermostatic control and overload protection without paying for features built for multi-fan or EC setups.
Usage guidance
The AC1 is designed to be plug and play.
Manual mode
Unplug the temperature sensor to run your fan continuously at the minimum speed you've set on the dial.
Thermostatic mode
Plug the sensor back in, position it centrally in your grow space away from direct airflow, and set your target temperature - the AC1 will hold the fan at minimum until that temperature is exceeded, then ramp up.
Setting tick-over speed
Use the minimum speed dial to set your fan's baseline "tick-over" rate anywhere from 20% to 100% before the thermostat kicks it up further.
Technical specifications
- Control type: Thermostatic AC fan speed control, single output
- Manufacturer: Global Air Supplies (G.A.S UK)
- Fan compatibility: Single-speed AC fans up to 5A (approx. 1150W)
- Sensor range: 20°C to 30°C, 0.5°C accuracy
- Ramp-up point: Approx. 2°C above set temperature
- Minimum speed range: 20% to 100% of full fan speed
- Cable: 2 metre supply cable with sensor included
- Safety: Built-in overload protection, defaults to full speed if controller overheats
Who this is for
- Growers running a single AC extraction or intake fan up to 5A
- New growers who want their first thermostatic controller without a big outlay
- Anyone who wants the option to switch between manual and automatic control
Best suited to single-tent setups using one AC fan rather than EC or multi-fan systems.
Our take
The AC1 covers the basics properly - real thermostatic control, sensible temperature accuracy, and overload protection built in, all for a single AC fan. It's not trying to do more than that, and it doesn't need to.
If you're running one AC fan and want it to respond to temperature automatically, this does exactly what it should, day in, day out.
