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Sequence of Operation
Low Ambient Dampers
Low Ambient Dampers are available as a factory installed
option or can be field-installed. Dampers are used to extend
the operation of these units from the standard operational
temperatures to a minimum of 0
or 10
o
F with hot gas bypass. (These values apply when
wind speed across the condenser coil is less than 5 m.p.h.).
If typical wind speeds are higher than 5 m.p.h., a wind
screen around the unit may be required. By restricting the
airflow across the condenser coils, saturated condensing
temperatures can be maintained as the ambient tempera-
tures change.
The low ambient damper actuator controls damper modula-
tion for each refrigerant circuit in response to saturated con-
densing temperature.
Chilled Water Circulating Pump
Once the system has been filled, complete the following
chilled water system start-up procedures.
1. Turn the 115 volt control circuit switch 1S1 and the 24
volt control circuit switch 1S70 located in the unit control
panel to the "Off" position.
2. Turn the main power disconnect switch and the control
circuit disconnect switch (5S1), for the solution pump, to
the "On" position.
3. Close the main power disconnect switch or circuit protec-
tor switch that provides the supply power to the unit's ter-
minal block 1TB1 or the unit mounted disconnect switch
1S14. The unit mounted disconnect switch (1S14), if ap-
plicable, must be closed.
4. Turn the 24 volt control circuit switch 1S70 located in the
unit control panel to the "On" position.
Note: To prevent the compressors from starting,
leave the 115 volt control circuit switch "Off".
5. Open the Human Interface access door, located in the
unit control panel, and press the SERVICE MODE key to
display the first service screen. Refer to the latest edition
of the Trouble Shooting Guide for the SERVICE TEST
screens and programming instructions.
6. Once the configuration for the pump is complete, press
the NEXT key until the LCD displays the "Start test in
__Sec." screen. Press the + key to designate the delay
before the test is to start. This service test will begin after
the TEST START key is pressed and the delay desig-
nated in this step has elapsed. Press the ENTER key to
confirm this choice.
o
F without hot gas bypass
System Start-Up
WARNING
Rotating Components!
During installation, testing, servicing and troubleshoot-
ing of this product it may be necessary to measure the
speed of rotating components. Have a qualified or li-
censed service individual who has been properly
trained in handling exposed rotating components, per-
form these tasks. Failure to follow all safety precau-
tions when exposed to rotating components could re-
sult in death or serious injury.
7. Press the TEST START key to start the test. Remember
that the delay designated in step 7 must elapse before
the pump will begin to operate.
Note: Pump operation is dependent upon proper
solution flow proving switch operation. Please see
section titled "Loss-Of Flow Protection: under
General Information for details.
8. To balance the flow through the evaporator, adjust the
flow rates between the minimum and maximum values
given in Table 9. Flow rates above or below these values
can cause equipment damage or improper unit opera-
tion.
9. Check the flow device (if applicable) on the evaporator
outlet piping to ensure it opens and closes properly.
10. Measure the evaporator water pressure drop at the sys-
tem pressure gauge(s). Compare the readings to the
pressure drop values given in Figure 13.
Note: Evaporator pressure drop is an
approximation and is to be used as a tool to
estimate flow rate and as an aid to waterside
system piping design. If an accurate measurement
of flow is required, a flow meter must be installed
in the system.
Ethylene Glycol Adjustment Factor
The addition of ethylene glycol to the chilled water system
reduces unit capacity. To determine the pressure drop of a
glycol solution system, obtain the pressure drop adjustment
factor from the chart in Figure 14 and multiply it times the
pressure drop of a water system without glycol, i.e:
Glycol sP = H
0 sP X Adjustment Factor.
2
Table 9
Evaporator Data for C20 through C60 Units
Water
Unit
Volume
Size
gal
C20
11.7
C25
10.7
C30
16.3
C40
13.8
C50
21
C60
37.8
46
Minimum
Maximum
Flow Rate
Flow Rate
litre
gpm
litre/s
gpm
44
24
1.5
72
40
30
1.9
90
62
36
2.3
108
52
48
3
144
79
60
3.8
180
143
72
4.5
216
litre/s
4.5
5.7
6.8
9.1
11.3
13.6
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