RefPlus EK Series - Start up; Leak Testing and Evacuation; Fan Motors; Fan Delay Defrost Termination Control

R
16
7. START-UP
CAUTION: Before starting unit, be sure wire fan
guards are secured in place over each fan.
7.1 LEAK TESTING AND EVACUATION
Leak testing and evacuation must be done in
accordance with local and national codes.
Once all refrigerant connections are made, leak test all
joints before charging the system with refrigerant. After
leak testing, all moisture and non-condensable gas must
be evacuated from the system. Attach high vacuum line
pump and gauge on both high and low pressure sides of the
system. A minimum vacuum level of 500 micron is required
to effectively remove moisture.
Be sure all valves such as compressor, hot gas, receiver,
and liquid solenoid valves are open. Break the vacuum in
the system with the refrigerant to be used. Always charge
the refrigerant into the system through a new 16 cu. in drier
(eld supplied) in the charging manifold line.
7.2 FAN MOTORS
Fan motors may cycle off on automatic thermal protection if
the coils are frozen or blocked. Check the supply voltage at
the motor leads if motor is inoperable. Also check direction
of rotation of the motors.
AWEF registered EJ, LJ & DJ models are limited to -30
o
F
room temperature and -40
o
F suction. Minimum fan speed is
set to 60% of its maximum. For air defrost units, minimum
fan speed is 50%.
IMPORTANT! For units equipped with variable-
speed ECM Blue motors, current provided to fan
motors must be applied at all times, specially
during winter operation. Refer to wiring diagram
13.14 on page 35 for more details.
7.3 FAN DELAY / DEFROST TERMINATION CONTROL
This control is located on the coil plate and senses the coil
temperature. To provide fan delay, the defrost thermostat
must be turned off.
To set the defrost termination / fan delay thermostat:
1. Set the cut-in temperature to approximately 50-60
o
F. This
will be your high event or the limit defrost temperature.
2. Set the differential temperature to approximately 20-30
o
F.
This will be your low event or fan cut-in temperature.
The idea is to have your evaporator coil temperature
below 32
o
F in order to avoid water carry over.
Example:
Cut-in defrost temperature=55
o
F (End defrost)
Cut-in fan temperature=30
o
F (Start fans)
Differential= 25
o
F (55-30=25)
7.4 FAN DELAY DRAIN PAN CONTROL
The fan delay drain pan control senses the general coil
temperature.
• With temperature rise, the fan delay thermostat de-
energizes the fan and energizes the electric pan heaters.
• After defrost cycle, the coil temperature drops below the
freezing point and the fan delay thermostat energizes
the fan motor and de-energizes the heaters.
• Defrost timer must be set long enough to completely
melt the ice in the unit. Set the thermostat at 20 to 25ºF
and the differential at minimum.
IMPORTANT: After correcting a faulty defrost cycle, it is
essential that the coil, drain pan and unit be free and clear of
ice before placing the unit back on automatic operation.
7.5 ADJUSTING EVAPORATOR PRESSURE AND
SUPERHEAT
What is Glide:
Understanding Glide is the key to maintaining the
desired temperature and protecting the compressor.
To reach EPA and Environment Canada's mandated lower
global warming potential (GWP) levels, the commercial
refrigeration industry has increasingly turned to refrigerant
blends. These blends are non-toxic, non-ammable and
operate within the typical commercial refrigeration operating
pressures.
Many technicians are accustomed to using refrigerants that
act as a single component with a boiling temperature that
doesn’t change within the evaporator. But with zeotropic
refrigerant blends, the temperature in the evaporator will be
colder at the start of the coil than at the end. Simply put, the
differences in these temperatures is the Glide.
Refrigerant Blends and Glide:
Refrigerant blends such as R-404A, R-407A, R-407C, R-407F,
R-448A and R-449A are a mixture of components that retain
their individual evaporating and condensing points.
With R-404A, the refrigerant glide is approximately 1
o
F and
can generally be ignored.
With R-407A, R-407C, R-407F, R-448A and R-449A,
refrigerant glide is much higher (6-10˚F) and yields higher
dew point condensing temperatures in comparison to R-404A
for equivalent performance
Why Glide Matters:
Because different components in a blend boil at different
temperatures, the temperature in the coil will vary as the
mixture boils. If the expansion valve adjustment isn’t made
using the Dew Point, two things can happen. FIRST, the
liquid may not vapourize before reaching the compressor,
which can cause inefciency and lead to compressor damage.
SECOND, the blend may completely boil part way through the
evaporator, leading to a loss of efciency and required xture
temperature.
START-UP