Carrier WeatherMaker 48KC Series - Page 38

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Table 15 — Enthalpy Operation No DCV (CO
2
Sensor) — 1 Speed Fan
*With stage 3 delay (STG3 DLY) in Advanced setup menu can turn on second stage of mechanical cooling Y2-O after the delay if the call for Y1-I and
Y2-I have not been satisfied.
Table 16 — Enthalpy Operation with DCV (CO
2
Sensor) — 1 Speed Fan
*With stage 3 delay (STG3 DLY) in Advanced setup menu can turn on second stage of mechanical cooling Y2-O after the delay if the call for Y1-I and
Y2-I have not been satisfied.
Table 17 — Single Enthalpy and Dual Enthalpy High Limit Curves
Enthalpy Settings
When the OA temperature, enthalpy and dew point are be-
low the respective setpoints, the Outdoor Air can be used for
economizing. Fig. 53 shows the new single enthalpy bound-
aries in the W7220. There are 5 boundaries (setpoints ES1
through ES5), which are defined by dry bulb temperature, en-
thalpy and dew point.
Refer to Table 17 for ENTH CURVE setpoint values.
The W7220 calculates the enthalpy and dew point using
the OA temperature and humidity input from the OA enthal-
py sensor. When the OA temperature, OA humidity and OA
dew point are all below the selected boundary, the economiz-
er sets the economizing mode to YES, economizing is avail-
able.
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.
Fig. 53 shows the 5 current boundaries. There is also a
high limit 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.
DEMAND
CONTROLLED
VENTILATION (DCV)
OUTSIDE AIR
GOOD TO
ECONOMIZE
Y1-I Y2-I
FAN
SPEED
Y1-O Y2-O OCCUPIED UNOCCUPIED
NONE NO
OFF OFF HIGH 0v/Off 0v/Off MIN POS Closed
ON OFF HIGH 24v/On 0v/Off MIN POS Closed
ON ON HIGH 24v/On 24v/On MIN POS Closed
NONE YES
OFF OFF HIGH 0v/Off 0v/Off MIN POS Closed
ON OFF HIGH 0v/Off 0v/Off
MIN POS to Full
Open
Closed to Full-Open
ON ON HIGH 24v/On 0v/Off*
MIN POS to Full
Open
Closed to Full-Open
DEMAND
CONTROLLED
VENTILATION (DCV)
OUTSIDE AIR
GOOD TO
ECONOMIZE
Y1-I Y2-I
FAN
SPEED
Y1-O Y2-O OCCUPIED UNOCCUPIED
Below CO
2
Set
No
OFF OFF HIGH 0v/Off 0v/Off VENTMIN Closed
ON OFF HIGH 24v/On 0v/Off VENTMIN Closed
ON ON HIGH 24v/On 24v/On VENTMIN Closed
Yes
OFF OFF HIGH 0v/Off 0v/Off VENTMIN Closed
ON OFF HIGH 0v/Off 0v/Off
VENTMIN to
Full-Open
Closed to Full-Open
ON ON HIGH 24v/On 0v/Off
VENTMIN to
Full-Open
Closed to Full-Open
Above CO
2
Set
No
OFF OFF HIGH 0v/Off 0v/Off
VENTMIN to
VENTMAX
Closed
ON OFF HIGH 24v/On 0v/Off
VENTMIN to
VENTMAX
Closed
ON ON HIGH 24v/On 24v/On
VENTMIN to
VENTMAX
Closed
Yes
OFF OFF HIGH 0v/Off 0v/Off
VENTMIN to
VENTMAX
Closed
ON OFF HIGH 0v/Off 0v/Off
VENTMIN to
Full-Open
Closed to Full-Open
ON ON HIGH 24v/On 0v/Off*
VENTMIN to
Full-Open
Closed to Full-Open
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