Fan Status Monitoring; Setting Up The System; Supply Fan Status Monitoring Logic; Dirty Filter Switch - Carrier 48AJ Operating And Service Manual

Fan Status Monitoring

GENERAL — The A Series ComfortLink™ controls offer the
capability to detect a failed supply fan through either a duct
static pressure transducer or an accessory discrete switch. The
fan status switch is an accessory that allows for the monitoring
of a discrete switch, which trips above a differential pressure
drop across the supply fan. For any unit with a factory-installed
duct static pressure sensor, it is possible to measure duct
pressure rise directly, which removes the need for a differential
switch. All 48/50AK,AW units with a factory-installed supply
fan VFD will have the duct static pressure sensor as standard.
SETTING UP THE SYSTEM — The fan status monitoring
configurations are located in Configuration
Table 71.
Table 71 — Fan Status Monitoring Configuration
ITEM EXPANSION
SFS.S Fan Fail Shuts Down Unit Yes/No
SFS.M Fan Stat Monitoring Type 0 - 2
Fan Stat Monitoring Type (SFS.M) — This configuration se-
lects the type of fan status monitoring to be performed.
0 - NONE — No switch or monitoring
1 - SWITCH — Use of the fan status switch
2 - SP RISE — Monitoring of the supply duct pressure.
Fan Fail Shuts Down Unit (SFS.S) — This configuration
will configure the unit to shut down on a supply fan status fail
or simply alert the condition and continue to run. When config-
ured to YES, the control will shut down the unit if supply fan
status monitoring fails and send out an alarm. If set to NO, the
control will not shut down the unit if supply fan status monitor-
ing fails but send out an alert.
SUPPLY FAN STATUS MONITORING LOGIC — Regard-
less of whether the user is monitoring a discrete switch or is
monitoring static pressure, the timings for both techniques are
the same and rely upon the configuration of static pressure
control. The configuration that determines static pressure
→
control is Configuration SP
set to 0 (none), a fan failure condition must wait 60 continuous
seconds before taking action. If this configuration is 1 (VFD), a
fan failure condition must wait 3 continuous minutes before
taking action.
If the unit is configured to monitor a fan status switch
(SFS.M = 1), and if the supply fan commanded state does not
match the supply fan status switch for 3 continuous minutes,
then a fan status failure has occurred.
If the unit is configured for supply duct pressure monitoring
(SFS.M = 2), then
• If the supply fan is requested ON and the static pressure
reading is not greater than 0.2 in. wg for 3 continuous
minutes, a fan failure has occurred.
• If the supply fan is requested OFF and the static pressure
reading is not less than 0.2-in. wg for 3 continuous min-
utes, a fan failure has occurred.
Dirty Filter Switch —
field-installed accessory dirty filter switch. The switch is located
in the filter section. If a dirty filter switch is not installed, the
switch input is configured to read "clean" all the time.
To enable the sensor for dirty filter monitoring set
→ →
Configuration UNIT SENS
state of the filter status switch can be read at Inputs
FLT.S. See Table 72.
→
UNIT. See
RANGE CCN POINT
SFS_SHUT
SFS_MON
→
SP.CF. If this configuration is
The unit can be equipped with a
→
FLT.S to ENABLE. The
→
GEN.I
Table 72 — Dirty Filter Switch Points
ITEM
→
Configuration UNIT
→ →
SENS FLT.S
→
Inputs GEN.I
→
FLT.S
Monitoring of the filter status switch is disabled in the
Service Test mode and when the supply fan is not commanded
on. If the fan is on and the unit is not in a test mode and the
filter status switch reads "dirty" for 2 continuous minutes, an
alert is generated. Recovery from this alert is done through a
clearing of all alarms or after cleaning the filter and the switch
reads "clean" for 30 seconds.
NOTE: The filter switch should be adjusted to allow for the
operating cfm and the type of filter. Refer to the accessory
installation instructions for information on adjusting the switch.
Economizer —
age the outside and return air dampers of the unit to provide
ventilation air as well as free cooling based on several
configuration options. This section contains a description of the
economizer and its ability to provide free cooling. See the
section on Indoor Air Quality for more information on setting
up and using the economizer to perform demand controlled
ventilation (DCV). See the Third Party Control section for
a description on how to take over the operation of the econo-
mizer through external control.
The economizer system also permits this unit to perform
smoke control functions based on external control switch
inputs. Refer to the Smoke Control Modes section for detailed
discussions.
Economizer control can be based on automatic control
algorithms using unit-based set points and sensor inputs. This
economizer control system can also be managed through exter-
nal logic systems.
The economizer system is a factory-installed option. This
unit can also have the following devices installed to enhance
economizer control:
• Outside air humidity sensor
• Return air humidity sensor
NOTE: All these options require the Controls Expansion Mod-
ule (CEM).
SETTING UP THE SYSTEM — The economizer configura-
tion options are under the Local Display Mode Configuration
→
ECON. See Table 73.
Economizer Installed? (EC.EN) — If an economizer is not
installed or is to be completely disabled the configuration
option EC.EN may be set to No. Otherwise in the case of an in-
stalled economizer, this option must be set to Yes.
Economizer Minimum Position (EC.MN) — The configura-
tion option EC.MN is the economizer minimum position. See
the section on Indoor Air Quality for further information on
how to reset the economizer further to gain energy savings and
to more carefully monitor IAQ problems.
Economizer Maximum Position (EC.MX) — The upper lim-
it of the economizer may be limited by setting EC.MX. It de-
faults to 98% to avoid problems associated with slight changes
in the economizer damper's end stop over time. Typically this
will not need to be adjusted.
→
57
EXPANSION RANGE
Filter Enable/
Stat.Sw.Enabled ? Disable
Filter Status Input DRTY/CLN FLTS
The Economizer Control is used to man-
CCN
POINT
FLTS_ENA