Emerson Copeland Scroll Series, Manual

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© 2017 Emerson Climate Technologies, Inc.
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AE5-1377 R3
There are two thermistors sensing the discharge line
temperature, one is located at the discharge line of the
compressor and the second one is placed at the inlet of
the condenser coil. In order to have a higher
temperature resolution, the discharge line thermistor
and condenser coil inlet sensor cooperate to sense a
temperature range from 50°F to 329°F. The discharge
line thermistor has a sensing range from 163°F to 329°F
and the condenser coil will sense temperature from 50°F
to 176°F. The EVI system will keep the discharge line
temperature below 230°F to ensure the safety of the
compressor.
It is important to insulate the system liquid line from the
condensing unit to the evaporator. The recommended
insulation thickness is a minimum of ½ inch. Also the
lower liquid temperature can increase the evaporator
expansion valve capacities. Please follow the valve
manufactures
recommended liquid temperature
correction factors for proper selection of the evaporator
expansion valve.
11. Electronic Expansion Value (EXV)
The Electronic Expansion Value (EXV) is a key part of
the EVI system. It will regulate vapor injection flow to
optimize the performance of system and cool the scroll
set. Every second, the control chip will collect the
thermistors reading and do a four second averaging.
The EXV opening will be changed every 20 seconds and
the variation is calculated by different ways based on
different purposes.
12. TXV selection
For EVI, Emerson recommends a balanced port TXV
because it offers a wider operating range for floating
liquid temperatures.
See Table 9 for specifics regarding balanced port sizing
recommendations. Applied with the low temp units it is
recommended that a balanced port expansion valve be
used along with a complete review of the the distributor
& nozzle (orifice) that is supplied with the Evaporator coil
being matched with the applicable condensing unit.
Typically nozzles are selected for standard TXV sizing
using 100°F liquid, with the XJAL those typical
selections could be grossly oversized. See
Table 9 for
the liquid correction safety factors when selecting those
components.
13. Other Inputs to the Control Board
13.1. Customer Supplied Control (Thermostat)
The control board will accept a normal 220 volt AC input
ON/OFF signal such as the switching action of a normal
commercial thermostat and relay. If the system is
controlled by low pressure control for a multiple
evaporator system and/or pump down system, the
control board will accept the signal directly from the
control. See Wiring Diagrams, for proper installation.
14. Other Outputs from the Control Board
14.1. Defrost Control Board for Units Produced
Prior to Mid- 2013
(using the control module shown in Figure 4 .) The
defrost control board is a basic time initiated module
which is standard on both low and medium temperature
units. The defrost control board can control either off-
cycle or electric defrost.
The defrost control board will control the liquid line
solenoid valve. When defrost is initiated the liquid line
solenoid valve will close and the unit will go into a
pumpdown cycle. When the suction pressure equals the
setting of the low pressure control, the compressor will
cycle off. After the defrost time has expired, the liquid
line solenoid valve opens and then
the low pressure control will allow the compressor to
restart.
On -002 and -012 models only, due to heater amperage
loads, electric defrost requires an additional relay or
contactor to energize the defrost heater. Relays capable
of 30 amp loads are supplied on the -022 models
The defrost cycle can be executed either automatically
or manually. There are two rotary dip switches by which
the user can set up the defrost cycle, see
Figure 4 . One
rotary dipswitch sets the defrost duration (SW1) and the
second rotary dipswitch sets the time interval between
defrost cycles (SW2). For automatic defrost set SW1
and SW2 as desired. See
Table 6 for time settings. The
defrost control board also incorporates a manual defrost
button that enables a manual defrost as an override to
the rotary switch setting the defrost interval. Upon the
completion of a manual defrost, the system will reset to
the refrigeration cycle with the same procedures as
automatic defrost and then the automatic defrost timer
will reset.
For setting manual defrost only set SW1 as desired and
set SW2 to “0”. Whenever the manual defrost button is
pressed, one defrost cycle will be executed and the
duration of defrost will be determined by the setting of
the rotary dipswitch SW1.
Note: There is no method to terminate a defrost cycle
without resetting the control board.
Table 6 lists rotary dip switch settings for the Defrost
Control Board.
An ON/OFF output connection is provided on the control
board (JP10) for direct connection of a customer