High-precision intelligent temperature controller with digital display designed for hot water circulation, return-water system control, and similar applications. Key benefits - Precise dual-sensor control that improves thermal efficiency by switching heating or cooling cycles based on the measured temperature difference between a high-temperature sensor and a low-temperature sensor. - Real-time digital tube display shows both high and low temperature values for immediate monitoring. - Isolated control power prevents voltage fluctuations on the control board when large power devices start or stop, improving system stability. - Automatic sensor detection and permanent parameter memory preserve settings and operating state after power loss. - Simple wiring and relay output make it easy to control pumps and other devices. Core functions and operation - Two operating modes - One-way mode: Relay A activates when high-temperature sensor value minus low-temperature sensor value exceeds the preset temperature difference. Relay A opens when the difference falls below the preset return difference. If low-temperature sensor value is greater than high-temperature sensor value, the relay remains inactive. - Two-way mode: Relay A activates when the absolute difference between the two sensor temperatures exceeds the preset temperature difference. Relay A opens when the difference falls below the preset return difference. - Hysteresis control: The device uses a preset temperature difference and a separate smaller return difference to avoid rapid on/off switching and to ensure stable cycling. - Example settings - Solar hot water circulation: Set temperature difference to 5.0 C and return difference to 0.5 C. When high-temp minus low-temp exceeds 5.0 C the relay drives the circulation pump; when the difference drops to 4.5 C the relay switches off. - Air convection cycle: Set temperature difference to 3.0 C and return difference to 0.3 C. When the difference exceeds 3.0 C the relay activates the fan or pump; when the difference drops to 2.7 C the relay deactivates. Technical parameters and notes - Control is based on the temperature difference between two measurement points (high temperature and low temperature) to operate water pumps or other outputs. - The device evaluates temperature difference as high sensor reading minus low sensor reading. - Automatic detection of connected sensors. If no sensor is present or only one probe is connected the alarm indicator will display 0000. - Non-volatile storage preserves the last parameter set and operating state after power off. - The product was originally designed with two relays. To avoid wiring errors the current version is supplied with a single relay and one white connector. Buyers should use the single-relay wiring provided. Connection and wiring - Power input: blue 2-pin connector. Plus is the positive terminal, minus is the negative terminal. A DC power supply can be connected directly. - Power wiring may be routed through the tubular connector; the flat right terminal can be used for actuation. - Output: relay output used to switch pumps and related equipment. Suitable applications - Solar hot water circulation systems where pump activation is required only when the collector is sufficiently hotter than the storage tank. - Return-water control and pump cycling in residential or light commercial hot water circulation systems. - Air convection or fan control based on temperature differences between two locations. Compatibility and performance - Designed for systems that require dual-sensor temperature difference control and relay switching for pumps or fans. - Provides stable cycling control with user-adjustable temperature difference and return difference settings to minimize unnecessary switching and improve heating or cooling efficiency. This controller offers clear dual-sensor monitoring, reliable hysteresis control, isolated control power for stable operation, and simple relay output wiring for pump and fan control.