Honeywell W7750A User Manual
EXCEL 10 W7750A,B,C CONSTANT VOLUME AHU CONTROLLER
49
74-2958—1
1.
Check the version numbers of the controller firmware,
E-Vision and the E-Vision script.
E-Vision and the E-Vision script.
2.
Check the wiring to the power supply and make sure
there is a good earth ground to the controller.
there is a good earth ground to the controller.
3.
Check the occupancy and HVAC modes.
4.
Compare the current actual setpoint with the actual
space temperature.
space temperature.
5.
Check the desired configuration settings.
6.
Check the network wiring and type of wire used.
7.
Check the Zone Manager mapping and referred points.
NOTE:
If the fan shuts off periodically for no specific reason
and the controller restarts the fan by itself after about
20 to 60 seconds, the cause could be a bad Air Flow
switch. If the controller has a digital input assigned
as a Proof of Air Flow input, try unconfiguring this
digital input to see if these shutdowns continue. If
not, adjust or replace the Air Flow switch to get it
working.
and the controller restarts the fan by itself after about
20 to 60 seconds, the cause could be a bad Air Flow
switch. If the controller has a digital input assigned
as a Proof of Air Flow input, try unconfiguring this
digital input to see if these shutdowns continue. If
not, adjust or replace the Air Flow switch to get it
working.
Temperature Sensor and Setpoint Potentiometer
Resistance Ranges
Resistance Ranges
The T7770 or T7560A,B Wall Modules or the C7770A Air
Temperature Sensor has the following specified calibration
points, which are plotted in Fig. 40:
Temperature Sensor has the following specified calibration
points, which are plotted in Fig. 40:
Temperature (°F)
Resistance Value (ohms)
98
11755
80
18478
70
24028
60
31525
42
52675
The T7770 Wall Module setpoint potentiometers have the
following calibration points:
following calibration points:
Temperature (°F)
Resistance Value (ohms)
85
1290
70
5500
55
9846
Fig. 40. Temperature sensor resistance plots.
Alarms
When an Excel 10 has an alarm condition, it reports it to the
central node on the L
central node on the L
ON
W
ORKS
Bus (typically, the Excel 10
Zone Manager). See Table 12. Information contained in an
alarm message is:
alarm message is:
• Subnet Number:
L
ON
W
ORKS
Bus subnet that contains the Excel 10 node
that has the alarm condition. Subnet 1 is on the Zone
Manager side of the router; Subnet 2 is on the other
side.
Manager side of the router; Subnet 2 is on the other
side.
• Node Number:
Excel 10 node that has the alarm condition (see
Network Alarm).
Network Alarm).
• Alarm Type:
Specific alarm being issued. An Excel 10 can provide
the alarm types listed in Table 12.
the alarm types listed in Table 12.
.
TEMPERATURE (DEGREES)
o
F
30
40
50
60
70
80
90
100
110
0
10
20
30
40
RESISTANCE (OHMS)
20K OHM AT
77
77
o
F (25
o
C)
80K
70K
60K
50K
40K
30K
20K
10K
o
C
M11620
AIR TEMPERATURE SENSOR
10K OHM SETPOINT POT
RESISTANCE VALUES
RESISTANCE VALUES
Table 12. Excel 10 Alarms.
Name of alarm or error bit
Alarm type
number
Meaning of alarm code or error bit
RETURN_TO_NORMAL
128U
Return to no alarm after being in an alarm condition. This code is added
numerically to another alarm code to indicate that the alarm condition has
returned to normal.
numerically to another alarm code to indicate that the alarm condition has
returned to normal.
ALARM_NOTIFY_DISABLED
255U
The alarm reporting was turned off by DestManMode. No more alarms are
reported until DestManMode turns on alarm reporting or on application restart.
reported until DestManMode turns on alarm reporting or on application restart.
NO_ALARM
0
No alarms presently detected.
INPUT_NV_FAILURE
1
One or more NV inputs have failed in receiving an update within their specified
FAILURE_DETECT_TIME.
FAILURE_DETECT_TIME.
NODE_DISABLED
2
The control algorithm has stopped because the controller is in
DISABLED_MODE, MANUAL or FACTORY_TEST mode. No more alarms are
reported when the controller is in the DISABLED_MODE. Alarms continue to be
reported if the controller is in the MANUAL or FACTORY_TEST mode.
DISABLED_MODE, MANUAL or FACTORY_TEST mode. No more alarms are
reported when the controller is in the DISABLED_MODE. Alarms continue to be
reported if the controller is in the MANUAL or FACTORY_TEST mode.
SENSOR_FAILURE
3
One or more sensors have failed.
FROST_PROTECTION_ALARM
4
The space temperature is below the frost alarm limit 42.8°F (6°C) when the
mode is FREEZE_PROTECT. The alarm condition remains until the temperature
exceeds the alarm limit plus hysterisis.
mode is FREEZE_PROTECT. The alarm condition remains until the temperature
exceeds the alarm limit plus hysterisis.
INVALID_SET_POINT
5
One of the setpoints is not in the valid range.