Technical information

UGH021/0301 VL Series Portable Chillers, 2 to 40 Tons
Page: 21
power supply. The operator must reverse the
power leads at the disconnect switch only and
NOT at the power entry terminals on the unit’s
electrical panel. The unit’s internal electrical
system wiring is phased correctly at the factory and
must not be altered in the field.
d. Visually inspect the rotation of the motor as
outlined step 1 to determine the unit is phased
correctly.
C. PROCESS FLOW ADJUSTMENTS
1. The operator must determine and set proper water flow
rate for the most efficient and trouble free operation.
a. Water flow rate through the process is determined
by the pressure losses in the process loop.
Generally, higher flow rates result in turbulent flow
achieving maximum temperature control and lower
maintenance. Since the evaporator in most liquid
chillers is flow sensitive, the efficiency of operation
is directly related to the flow of liquid.
b. Maximum chiller efficiency is obtained at
approximately 2.4 gpm per ton of rated capacity.
Low liquid flow can reduce efficiency and in some
cases allow ice to form in the evaporator which can
damage the evaporator. Excessive flow will trip the
motor overload protection circuit.
2. Activate the CHILLER ON rocker switch on the display to
activate the process pump. Wait a few moments to allow air
to be purge from system. Two items the operator must look
for are low or excessive flow conditions.
3. LOW FLOW... to allow operation under a low flow
condition, it is necessary to install a flow bypass system in
the process circuitry. This will allow a portion of the flow to
bypass the process and return directly to the chiller. This
keeps the total flow above the cutoff point. Figure 3.2D
illustrates a typical bypass loop.
21 GPM 5 GPM
5 GPM21 GPM
BYPASS
THROTTLING
VALVE -
16 GPM
CHILLER PROCESS
Figure 3.2D Typical low flow by-pass loop