USDT 2004B Basic Solar Differential Controller

digital display, adjustable trigger from 4.1°F to 99°F, 115vac

A basic temperature differential controller for solar water heating systems, this microprocessor based temperature controller regulates solar water heating systems and any other heating systems such as: storage tank charging and boiler activation systems. The USDT 2004B monitors and displays supply and return temperatures. When the supply temperature exceeds the return temperature by a programmable temperature difference (?T), an internal relay powers a 0.25 HP pump or an auxiliary relay.

To avoid overheating the controlled system, the controller stops the pump when the supply temperature reaches a programmable maximum temperature (T_MAX). The controller offers an adjustable delay to temperature measurements to avoid pump cycling on and off too quickly.

Features

• Precise digital differential controller for efficient heat collection
• Digital display of collector (supply, T_c) temperature
• Digital display of collector (return, T_t) temperature
• Adjustable Delta T (?T) differential
• Manual override of outputs for system testing
• Over-heating pump stop for system boiling protection
• Digital display of tank (return system) temperature
• User friendly diagnostics system
• Collector status screen
• Sensor cables can be extended up to 500 feet using standard two wire cables

USDT 2004B controller includes:

• Two inputs for temperature sensors
• Two thermistor sensors with connecting wire
• Collector sensor is supplied with a weather resistant terminal box and EMI impedance
• protector
• Adjustable hysteresises (delays to reporting temperature measurements) on all inputs
• Adjustable overheating protection
• Adjustable (4.1 °F to 99 °F) temperature difference (?T)
• Manual pump operation for system testing
• Exchangeable 3.5 amp system protection fuse
• System diagnostic and status displays
• Collector sensor surge protection
• Digital display of all parameters
• The system diagnostics displays potential system problems such as sensor or pump failures.

Power input specifications

• 115 VAC
• Maximum load 3.5 amps (400 watts)
• This device should be properly grounded. Flexible wires simplify connection to the terminals. All connections should be secure and adequately tightened. Best practices dictate keeping main cables away from sensor cables and other low voltage signal cables. A surge arrester at the collector sensor reduces risk of lightning damage to the controller's internal electronics.

alternate ref. AT ESR21-R