Digital Day/Night Temperature Controller

What the BETA-4 Does

The TrolMaster BETA-4 is a single-outlet temperature controller that accepts one heating or cooling device — a heater, portable A/C unit, or exhaust fan — rated at 10 amps or less. You configure a separate temperature setpoint for daytime and nighttime, and the controller switches your connected device on or off automatically to hold that target.

Day/night status is determined by the unit's built-in photocell rather than a separate timer input. When the photocell detects light (grow lights on), the controller enforces your day setpoint. When the room goes dark, it shifts to your night setpoint — no additional wiring or programming required.

The LED display shows current room temperature in real time and lets you pull up the recorded max and min temperatures from the current session, giving you a quick sanity check on whether your environment stayed on target overnight or during an extended dark period.

Who It's Built For

The BETA-4 is built for facilities that need reliable day/night temperature differentiation without the overhead of a full environmental controller. It's a strong fit for single-zone or single-device control scenarios: a supplemental heater in a veg room, an exhaust fan tied to a cooling threshold, or a portable A/C in a smaller flower space.

Licensed cannabis and hemp operators running discrete rooms — particularly those working in converted space where full HVAC integration isn't in the budget yet — use the BETA-4 to bring consistent, photocycle-aware temperature management to individual zones. It's equally relevant on a commercial propagation bench where a seedling heat mat or small space heater needs a precise low-end floor without running all night at the same threshold as the lit period.

The plug-and-play design — 120V NEMA 5-15 input, single switched outlet on the bottom — means there's no panel integration required. Wall-mount the controller, run the 16-foot sensor cable to canopy height, plug in the device, and you're running.

Key Features

Built-in photocell automatically detects light-on and light-off status, eliminating the need for a separate timer or relay to trigger day/night mode switching. Setpoints are configured independently using the three-button interface directly on the unit — press the Home button to cycle between day and night setpoints, and use the Up/Down buttons to adjust. Changes are saved automatically.

The LED screen is the primary interface for both setup and monitoring. It displays current temperature, active mode (heating or cooling), and whether the connected device is currently energized. The unit also retains max/min temperature records during operation so you can verify environmental stability without a separate data logger.

Mode selection — heating or cooling — is set on the controller to match the type of device you're plugging in. In heating mode, the outlet energizes when the temperature drops below setpoint. In cooling mode, the outlet energizes when the temperature rises above setpoint. The 5°F deadband prevents short-cycling of connected equipment.

The included temperature sensor ships with a 16-foot cable, long enough to position the probe at plant canopy level while the controller is wall-mounted at a comfortable working height outside the immediate canopy zone.

Fitting the BETA-4 Into Your Build

The BETA-4 sits in TrolMaster's Legacy Beta Series — a line of standalone, single-function environmental controllers designed for growers who want purpose-built control over specific parameters without full system integration. It complements rather than competes with TrolMaster's Hydro-X or Aqua-X platforms, making it a natural addition to any room not yet on a networked controller.

For operators running multiple zones, it's common to deploy one BETA-4 per room or per device — a propagation room heater, a flower room portable A/C, a drying room supplemental fan. Each unit is self-contained and independently set, so zone-by-zone configuration doesn't require any cross-unit coordination.

Installation is straightforward: mount to the wall in a position where the photocell has line-of-sight to your grow lights, route the sensor cable to the canopy, plug into a standard 120V outlet, and connect your heating or cooling device to the switched outlet on the bottom. No tools beyond a wall anchor, no electrician required for the controller itself.