Bryant Legacy 547K 14, Руководство по установке

Страница: 34 / 44

34
2SP H/C (2 SPEED HEAT/COOL) SPEED FAN OPERATION
FAN TYPE = 2SP H/C is not used on 547K*14 units
3 SPEED FAN OPERATION
FAN TYPE = 3SPEED is not used on 547K*14 units
ENTHALPY SETTINGS
When the OA temperature, enthalpy and dew point are below
the respective set points, the Outdoor Air can be used for econ -
omizing. Figure 49 shows the new single enthalpy boundaries
in the W7220. There are 5 boundaries (set points ES1 through
ES5), which are defined by dry bulb temperature, enthalpy and
dew point.
Refer to Table 12 for ENTH CURVE set point values.
The W7220 calculates the enthalpy and dew point using the
OA temperature and humidity input from the OA enthalpy sen -
sor. When the OA temperature, OA humidity and OA dew
point are all below the selected boundary, the economizer sets
the economizing mode to YES, economizing is available.
When all of the OA conditions are above the selected bound -
ary, the conditions are not good to economize and the mode is
set to NO.
Figure 49 shows the 5 current boundaries. There is also a high
limit boundary for differential enthalpy. The high limit bound -
ary is ES1 when there are no stages of mechanical cooling en -
ergized and HL (high limit) when a compressor stage is
energized.
Table 12 provides the values for each boundary limit.
Fig. 49 — Single Enthalpy Curve Boundaries
Economizing
Available
Not Available
Enthalp
y
RA Hum (%RH)
RA T
emp
Temperature
Absolute Humidity
ES5 ES4 ES3 ES2 ES1 HL
P1
(T,RH)
P2 (T,RH)
Single Enthalpy
Dual Enthalpy
High Limit
Table 12 — 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