51
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
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.
TWO-SPEED FAN OPERATION
NOTE: Two-Speed Fan operation applies to size 07 models only.
The W7220 controller has the capability to work with a system us
-
ing 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 posi
-
tion, see Table 28.
The W (heating mode) is not controlled by the W7220 but it re
-
quires 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 programmed
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 Ad
-
vanced 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.
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 41.
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 17) 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 41.
Checkout Tests
Use the Checkout menu (see page 46) 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 41.
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.
TROUBLESHOOTING
Alarms
The economizer module provides alarm messages that display on
the 2-line LCD.
NOTE: Upon power up, the module waits 60 minutes before
checking for alarms. This allows time for all the configured
Table 27 — 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
Table 28 — Fan Speed
STATE
FAN SPEED
OCC
Low
Y1
Low
Y2
High
W
High
CAUTION
EQUIPMENT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage.
Be sure to allow enough time for compressor start-up and
shutdown between checkout tests so that you do not short-
cycle the compressors.
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