K90-KPCS-IM-2
18/04/22
- 14 -
Low Pressure Control Settings
Minimum
Temperature °F *
R134a
R22
R404A
R507
R407A
R407A
R407C
R448A
R448A
R449A
R449A
Cut-in (PSIG)
Cut-out
(PSIG)
Cut-in (PSIG)
Cut-out
(PSIG)
Cut-in (PSIG)
Cut-out
(PSIG)
Cut-in
(PSIG)
Cut-out (PSIG)
50
35
5
70
20
85
30
65
20
40
25
5
55
20
70
30
50
20
30
17
5
40
20
50
30
35
20
20
12
0
30
10
40
20
25
5
10
7
0
20
0
30
10
15
0
0
5
0
15
0
20
5
10
0
-10
-
-
15
0
15
0
10
0
-20
-
-
10
0
10
0
7
0
-30
-
-
10
0
6
0
7
0
* The coldest Temperature of either the fixture or outdoor ambient.
High Pressure Control Settings
Refrigerant
Maximum Cut-out (PSIG)
Air-Cooled Units
Water Cooled Units
R134a
250
200
R22
350
315
R407A
R407A
R407C
R448A
R448A
R449A
R449A
400
315
LOW TEMPERATURE ROOM PULL-DOWN
It can take up to two weeks to properly start-up and pull-down a
large freezer. Large freezers should be pull-down to temperature
in stages. Too fast a pull-down can cause structural problems in
pre-fabricated rooms and will damage (crack) concrete floors.
Reduce room temperature by 10 to 15°F
(5.6 to 8.4°C)
per day.
Hold this temperature for 24 to 48 hours at 35°F
(1.7 °C)
and
again at 25°F
(-3.9 °C)
. Monitor the amount of defrost water
during this pull down stage.
Once the room is pulled down to temperature, expect frost on the
compressor end bell and any exposed suction line. A lack of frost
in these areas probably indicates too high of suction superheat.
Reduce defrost frequency to 30 minutes every 6 hours if possible.
Adjust the defrost termination (and time clock) so that the coil
and drain pan are
COMPLETELY
free of frost / ice at termination.
Too short of a defrost cycle will allow residual ice to grow. Too
long of a defrost will allow the coil(s) to steam at the end of
the cycle. The steam will condense and freeze fans, fan guards
and create frosting on the ceiling of the room. The evaporator
fan delay must allow any condensate left on the coil surface to
refreeze before the fans start.
SYSTEM START-UP CHECK LIST (cont’d)
