45
Fig. 52 — Single Enthalpy Curve Boundaries
ENTHALPY SETTINGS
When the OA temperature, enthalpy and dew point are below the
respective set points, the Outdoor Air can be used for economiz-
ing. Figure 52 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 25 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 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 52 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.
CHECKOUT
Inspect all wiring connections at the economizer module’s termi-
nals, and verify compliance with the installation wiring diagrams.
For checkout, review the Status of each configured parameter and
perform the Checkout tests.
NOTE: For information about menu navigation and use of the
keypad see Interface Overview on page 38.
Power Up
After the W7220 module is mounted and wired, apply power.
Initial Menu Display
On initial start up, Honeywell displays on the first line and econo-
mizer W7220 on the second line. After a brief pause, the revision
of the software appears on the first line and the second line will be
blank.
Power Loss (Outage or Brownout)
All set points and advanced settings are restored after any power
loss or interruption.
NOTE: All settings are stored in non-volatile flash memory.
Status
Use the Status menu (see Table 19) to check the parameter values
for the various devices and sensors configured.
NOTE: For information about menu navigation and use of the
keypad, see Interface Overview on page 38.
Checkout Tests
Use the Checkout menu (see page 42) to test the damper operation
and any configured outputs. Only items that are configured are
shown in the Checkout menu.
NOTE: For information about menu navigation and use of the
keypad, see Interface Overview on page 38.
To perform a Checkout test:
1. Scroll to the desired test in the Checkout menu using the ▲
and ▼ buttons.
2. Press the (Enter) button to select the item. RUN?
appears.
3. Press the (Enter) button to start the test. The unit pauses
and then displays IN PROGRESS. When the test is complete,
DONE appears.
4. When all desired parameters have been tested, press the
(Menu Up) button to end the test.
The Checkout tests can all be performed at the time of installation
or at any time during the operation of the system as a test that the
system is operable.
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
Table 25 — 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
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