Sub-Zero 315I - Operational Cycles

Theory of Operation
Model 315I (UC Ice Maker)
3-4
#3757320 - Revision B - August, 2005
OPERATIONAL CYCLES
There are two operational cycles of the icemaker:
• Ice Making (Freeze) Cycle
• Harvest Cycle
The ice making (freeze) cycle happens when water from the reservoir is sprayed into the ice cube molds at the bot-
tom of the evaporator and the water freezes into cubes. The harvest cycle is when the ice cubes are released from
the cube molds and fresh water enters the reservoir. The complete process takes approximately 30 minutes for
each batch of ice. (1 Freeze Cycle + 1 Harvest Cycle = 1 Batch of 8 Cubes.)
Ice Making (Freeze) Cycle
During the ice making cycle the compressor pumps refrigerant through the system, the condenser fan draws air over
the condenser, and the circulating spray pump sprays water into the cube molds. The refrigerant running through
the evaporator absorbs heat from the water being sprayed into the cube molds and the water begins to freeze. The
heat that the refrigerant absorbs from the water is carried in the refrigerant back to the compressor and then through
the condenser where the heat is transferred from the refrigerant to the air being drown over the condenser tubing by
the condenser fan. This warm air is discharged out through the louvered kickplate. When the cube molds become
cold enough, the ice machine’s timer begins to turn. When the timer turns far enough, it stops the ice making
(freeze) cycle and begins the harvest cycle.
NOTE: The Water System During Ice Making (Freeze) Cycle - The water system initially fills the reservoir with
approximately two quarts of water. During the ice making cycle, water is taken from the reservoir and sprayed into
the cube molds where it begins to freeze. But, due to the fact that water containing mineral impurities needs a lower
temperature to freeze, the impure water falls back into the reservoir and the purer water freezes in the cube molds.
This causes the water in the reservoir to become highly concentrated with mineral impurities towards the end of the
ice making (freeze) cycle.
Figure 3-4. Ice Making (Freeze) Cycle
Compressor
(ON)
Condenser Fan
(ON)
H
ot
Gas
V
a
lv
e
(
CLOSED
)
Evaporator
(Removing Heat
from Water)
Wa
t
e
r T
ube
Reservoir
Circulating
Spra
y
Pum
p
(ON)
C
ube For
m
in
Mo
l
ds
Inlet Water
Valve
(CLOSED)