Sterlco SEU Series Economical Water TCU - Manual (Page 27)

WTR1-600 Chapter 4: Controls 27 of 42
The 115V control circuit and controller outputs are fuse protected. The pump motor is controlled
by a full voltage magnetic non-reversing motor starter, with fused branch circuit overcurrent and
thermal overload protection.
Automatic Vent
This feature automatically triggers the purging of air from the system before you start the unit.
The vent actuates the solenoid valve, and forces trapped air and water out through the drain,
properly filling and priming the unit prior to startup. Complete venting is necessary to prevent
damage to the pump and heater.
The vent process is controlled through a timer. If you have a large process, you may need to
complete the venting process by pressing the VENT button on the front-mounted switch panel.
Pressure Switch
A pressure switch built into each unit keeps the system from starting until the water supply is
turned On and subjected to the minimum water supply pressure. This feature protects the pump
seal and the heater from damage through attempted operation without water. The pressure switch
is set at approximately 16 psig (110.32 kPa/1.10 bars) for 250°F (121ºC) units or 55 psig (379.23
kPa/3.79 bars) for 300°F (149ºC) units prior to leaving the factory
4-2 The microprocessor Controller
The controller is an easy-to-operate microprocessor-based PID control device. When the process
reaches the set point, the PID control cycles the cooling valve and/or immersion heater to
maintain the proper leaving water temperature.
The controller has been fully factory tested. Set the desired process temperature set point and the
control does the rest.
Built-in range of operation on the controller is 0°F to 250°F (-18ºC to 121ºC).
4-3 Controller Display
See figure 7
Figure 7
Typical 3216
Microprocessor Controller