36
Fig. 42 — Single Enthalpy Curve Boundaries
Table 23 — Single Enthalpy and Dual Enthalpy High Limit Curves
Enthalpy Settings — When the OA temperature, enthalpy and
dew point are below the respective setpoints, the outdoor air
can be used for economizing. Figure 42 shows the new 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 23 for ENTH CURVE setpoint 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
boundary, the conditions are not good to economize and the
mode is set to NO.
Fig. 42 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 ener-
gized.
Table 23 provides the values for each boundary limit.
Two-Speed Fan Operation
NOTE: Two-Speed Fan operation does not apply to 48TC 04-
06 units.
The W7220 controller has the capability to work with a sys-
tem using a 2-speed supply fan. The W7220 does not control
the supply directly but uses the following input status to
determine the speed of the supply fan and controls the OA
damper to the required position, see Table 24.
Table 24 — Fan Speed
The W (heating mode) is not controlled by the W7220 but it
requires the status to know where to position the OA damper
for minimum position for the fan speed.
The 2 speed fan delay is available when the system is pro-
grammed for 2 speed fan (in the System Setup menu item). The
2 speed fan delay is defaulted to 5 minutes and can be changed
in the Advanced Setup menu item. When the unit has a call for
Y1 In and in the free cooling mode and there is a call for Y2 In,
the 2-speed fan delay starts and the OA damper will modulate
100% open, the supply fan should be set to high speed by the
unit controller.
After the delay one of two actions will happen:
• The Y2–In call will be satisfied with the damper 100%
open and fan on high speed and the call will turn off
OR
• If the call for additional cooling in the space has not been
satisfied then the first stage of mechanical cooling will
be enabled through Y1 Out or Y2 Out.
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
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
STATE
FAN SPEED
OCC
Low
Y1
Low
Y2
High
W
High
Содержание WeatherMaker 48TC 04
Страница 4: ...4 Fig 2 Unit Dimensional Drawing ...
Страница 5: ...5 Fig 2 Unit Dimensional Drawing cont ...
Страница 21: ...21 Fig 34 48TC B07 Unit with Humidi MiZer Adaptive Dehumidification System Humidistat Wiring ...
Страница 39: ...39 Fig 45 PremierLink Wiring Schematic ...
Страница 40: ...40 Fig 46 PremierLink Wiring Schematic with Humidi MiZer System ...
Страница 48: ...48 Fig 65 Typical RTU Open System Control Wiring Diagram ...
Страница 49: ...49 Fig 66 Typical RTU Open System Control Wiring Diagram with Humidi MiZer System ...
