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54
ECONOMIZER CONTROL CONFIGURATIONS
Enthalpy Changeover Control
Economizer changeover based on outdoor air enthalpy requires an
outdoor air enthalpy sensor to replace the OAT sensor. The enthal
-
py sensor is available as a factory-installed option or as a field-in
-
stalled accessory (P/N HH57AC081). See Fig. 1 for model num
-
ber nomenclature; check Position #15 for codes R or S indicating
a factory-installed enthalpy sensor. Use Fig. 72 and Table 10 to
select the enthalpy changeover setting to enter in menu item
SETPOINTS –> ENTH CURVE.
Enthalpy Settings
When the OA temperature, enthalpy and dew point are below the
respective setpoints, the Outdoor Air can be used for economiz
-
ing. Fig. 72 shows the single enthalpy boundaries in the W7220.
There are 5 boundaries (setpoints ES1 through ES5), which are
defined by dry bulb temperature, enthalpy and dew point.
Refer to Table 10 for ENTH CURVE setpoint values.
The W7220 calculates the enthalpy and dew point using the OA
temperature and humidity input from the OA enthalpy sensor.
When the OA temperature, OA humidity and OA dew point are
all below the selected boundary, the economizer sets the econo
-
mizing mode to YES, economizing is available.
When all of the OA conditions are above the selected boundary,
the conditions are not good to economize and the mode is set to
NO.
Figure 72 shows the 5 current boundaries. There is also a high lim
-
it boundary for differential enthalpy. The high limit boundary is
ES1 when there are no stages of mechanical cooling energized and
HL (high limit) when a compressor stage is energized.
Table 10 provides the values for each boundary limit.
Fig. 72 —
Single Enthalpy Curve Boundaries
Table 10 —
Single Enthalpy and Dual Enthalpy High Limit Curves
ENTHALPY
CURVE
TEMP. DRY
BULB (F)
TEMP.
DEWPOINT (F)
ENTHALPY
(BTU/LB/DA)
POINT P1
POINT P2
TEMP. (F)
HUMIDITY
(%RH)
TEMP. (F)
HUMIDITY
(%RH)
ES1
80
60
28.0
80
36.8
66.3
80.1
ES2
75
57
26.0
75
39.6
63.3
80.0
ES3
70
54
24.0
70
42.3
59.7
81.4
ES4
65
51
22.0
65
44.8
55.7
84.2
ES5
60
48
20.0
60
46.9
51.3
88.5
HL
86
66
32.4
86
38.9
72.4
80.3
ECONOMIZING
AVAILABLE
NOT AVAILABLE
ENTHALPY
RA
HUM (%RH)
RA
TEMP
TEMPERATURE
ABSOLUTE HUMIDITY
ES5
ES4
ES3
ES2
ES1
HL
P1
(T,RH)
P2 (T,RH)
SINGLE ENTHALPY
DUAL ENTHALPY
HIGH LIMIT
Summary of Contents for WeatherExpert 50LC14
Page 4: ...4 Fig 2 50LC Vertical Airflow Size 14...
Page 5: ...5 Fig 3 50LC Horizontal Airflow Size 14...
Page 6: ...6 Fig 4 50LC Back View and Condensate Drain Location Size 14...
Page 7: ...7 Fig 5 50LC Corner Weights and Clearances Size 14...
Page 8: ...8 Fig 6 50LC Bottom View Size 14...
Page 9: ...9 Fig 7 50LC Vertical Airflow Sizes 17 20...
Page 10: ...10 Fig 8 50LC Horizontal Airflow Sizes 17 20...
Page 11: ...11 Fig 9 50LC Back View and Condensate Drain Location Sizes 17 20...
Page 12: ...12 Fig 10 50LC Corner Weights and Clearances Sizes 17 20...
Page 13: ...13 Fig 11 50LC Bottom View Sizes 17 20...
Page 14: ...14 Fig 12 50LC Vertical Airflow Sizes 24 26...
Page 15: ...15 Fig 13 50LC Horizontal Airflow Sizes 24 26...
Page 16: ...16 Fig 14 50LC Back View and Condensate Drain Location Sizes 24 26...
Page 17: ...17 Fig 15 50LC Corner Weights and Clearances Sizes 24 26...
Page 18: ...18 Fig 16 50LC Bottom View Sizes 24 26...
Page 21: ...21 Fig 19 Roof Curb Details 14 Size Unit...
Page 22: ...22 Fig 20 Roof Curb Details 17 and 20 Size Units...
Page 23: ...23 Fig 21 Roof Curb Details 24 and 26 Size Units...
Page 30: ...30 Fig 42 50LC 14 26 Electro Mechanical Control Wiring Diagram...
Page 31: ...31 Fig 43 50LC 14 26 RTU Open Control Wiring Diagram...
Page 32: ...32 Fig 44 50LC 14 26 SystemVu Control Wiring Diagram...
Page 35: ...35 Fig 47 Typical Power Wiring Diagram SystemVu Controls 50LC Unit 208 230V Shown...
Page 36: ...36 Fig 48 Typical Power Wiring Diagram SystemVu Controls 50LC Unit 460V 575V Shown...
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