TC 120
682.98767.00 • 10/04/2018
34
5-4 Sequence of Operation
The simplicity of design and the highly engineered controller make this unit almost self-
operating. The
START
,
STOP
, and
VENT
buttons and the temperature controller buttons
are all that is required to operate this unit.
After you complete all connections, turn the water supply
ON
, then turn control power
ON
.
The unit automatically vents for a preset time of one (1) minute. If you need additional vent
time, press the
VENT
button on the control panel.
As the water comes in the water supply line, the water must enter the pump, up through the
tank and out through the delivery line, through the process, back through the return line, and
through the solenoid line and out the drain line.
At this time, watching the drain for bubbles or erratic flow will indicate whether or not the
system has been properly vented. If a steady stream flows from the drain line, it is certain
that all the air is out of the system.
TCU systems provide temperature control on processes by directly
heating the process water and injecting cooling water into the
process water.
When the unit is energized, the pump starts and a one-minute vent
sequence opens the cooling/vent valve to remove any air trapped in
the process piping.
If the cooling water supply pressure is insufficient, the low cooling
water pressure cutout switch (set at 16 psig, 10 psig differential [110
kPa/1.1 bar, 69 kPa/0.7 bar differential]) opens, the
LOW WATER
PRESSURE
indicator lights, and the unit does not operate until the
pressure is 16 psig (110 kPa/1.1 bar) or more.
You need
at least 16
psig
(110 kPa/1.1 bar) for the best cooling capacity and to prevent
water boiling in the process circuit at high temperatures, particularly
at the pump suction.
After venting, the microprocessor controller monitors the
TO
PROCESS
sensor, cycling open the cooling/vent valve to discharge
warm water or energizing the immersion heater to maintain the
process set temperature.
5-5 Checking Motor Rotation Direction
Check for correct pump rotation direction by looking at the motor impeller. Press the
START
button and the
STOP
button, and note the direction that the motor turns. Rotation should be
clockwise
when viewed from the motor end.
Note:
Make sure that a qualified electrician performs the following steps.