Title 24 Fdd Configuration Points - Carrier 48HC 04-28 Controls, Start-Up, Operation And Troubleshooting

The control shall log a "damper not modulating" alert if:
1. SAT has not decreased by T24SATMD degrees F
SAT_SET/2 seconds after opening the economizer at least
T24ECSTS%, taking into account whether the entire move-
ment has occurred within the range 0 to T24TSTMN%.
2. SAT has not increased by T24SATMD degrees F
SAT_SET/2 seconds after closing the economizer at least
T24ECSTS%, taking into account whether the entire
movement has occurred within the range T24TSTMX to
100%.
3. Economizer reported position <=5% and SAT is not
approximately equal to RAT. SAT not approximately equal
to RAT shall be determined as follows:
a. SAT<RAT-(2*2(thermistor accuracy) + 2 (SAT
increase due to fan)) or
b. SAT>RAT+(2*2(thermistor accuracy) + 2 (SAT
increase due to fan))
4. Economizer reported position >=95% and SAT is not
approximately equal to OAT. SAT not approximately
equal to OAT shall be determined as follows:
a. SAT<OAT-(2*2(thermistor accuracy) + 2 (SAT
increase due to fan)) or
b. SAT>OAT+(2*2(thermistor accuracy) + 2 (SAT
increase due to fan))
2. Actuator Stuck or Jammed
The control shall test for a jammed actuator as follows:
• If the actuator has stopped moving and the reported posi-
tion (ECONOPOS) is not within ± 3% of the commanded
position (ECONOCMD) after 20 seconds, a "damper stuck
or jammed" alert shall be logged.
• If the actuator jammed while opening (i.e., reported posi-
tion < commanded position), a "not economizing when it
should" alert shall be logged.
• If the actuator jammed while closing (i.e., reported posi-
tion > command position), the "economizing when it
should not" and "too much outside air" alerts shall be
logged.
The control shall automatically clear the jammed actuator
alerts as follows:
• If the actuator jammed while opening, when ECONOPOS
> jammed position the alerts shall be cleared.
• If the actuator jammed while closing, when ECONOPOS <
jammed position the alerts shall be cleared.

TITLE 24 FDD CONFIGURATION POINTS

LOG.F (T24LOGFL) — "Log Title 24 Faults" — defines when
Title 24 mechanically disconnected actuator faults should be
logged:
Range=YES, NO,
YES — attempt to detect and log mechanically disconnect ac-
tuator
NO — do not attempt to detect and log mechanically discon-
nect actuator
Default=NO
EC.MD (T24ECMDB) — "T24 Econ Move Detect" —
amount of change required in economizer reported position be-
fore economizer is detected as moving
Range=1-10
Default=1
EC.ST (T24ECSTS) — "T24 Econ Move SAT Test" — mini-
mum amount economizer must move in order to trigger the test
for a change in SAT, i.e., the economizer must move at least
T24ECSTS % before the control will attempt to determine
whether the actuator is mechanically disconnected.
Range=10-20
Default=10
S.CHG (T24SATMD) — "T24 Econ Move SAT Change" —
minimum amount (in degrees F) SAT is expected to change
based on economizer position change of T24ECSTS.
Range=0-5
Default=.2
E.SOD (T24SRATDF) — "T24 Econ RAT-OAT Diff" — mini-
mum difference (in degrees F) between RAT (if available) or
SAT (with economizer closed and fan on) and OAT to perform
mechanically disconnected actuator testing.
Range=5-20
Default=15
E.CHD (T24CHDLY) — "T24 Heat/Cool End Delay" —
amount of time (in minutes) to wait after mechanical cooling or
heating has ended before testing for mechanically disconnected
actuator. This is to allow SAT to stabilize at conclusion of me-
chanical cooling or heating.
Range=0-60
Default=25
SAT.T (SAT_SET) — "SAT Settling Time" — SAT_SET/2 is
the amount of time (in seconds) economizer reported position
must remain unchanged (±T24ECMDB) before the control will
attempt to detect a mechanically disconnected actuator. This is
to allow SAT to stabilize at the current economizer position.
This configuration sets the settling time of the supply air tem-
perature (SAT). This typically tells the control how long to
wait after a stage change before trusting the SAT reading, and
has been reused for Title 24 purposes.
Range=10-900
Default=240
ET.MN (T24TSTMN) — "T24 Test Minimum Pos" — mini-
mum position below which tests for a mechanically discon-
nected actuator will not be performed. For example, if the actu-
ator moves entirely within the range 0 to T24TSTMN a deter-
mination of whether the actuator is mechanically disconnected
will not be made. This is due to the fact that at the extreme
ends of the actuator movement, a change in position may not
result in a detectable change in temperature. When the actuator
stops in the range 0 to 2% (the actuator is considered to be
closed), a test shall be performed where SAT is expected to be
approximately equal to RAT. If SAT is not determined to be ap-
proximately equal to RAT, a "damper not modulating" alert
shall be logged.
Range=0-50
Default=15
ET.MX (T24TSTMX) — "T24 Test Maximum Pos" — maxi-
mum position above which tests for a mechanically discon-
nected actuator will not be performed. For example, if the actu-
ator moves entirely within the range T24TSTMX to 100 a de-
termination of whether the actuator is mechanically
disconnected will not be made. This is due to the fact that at the
extreme ends of the actuator movement, a change in position
may not result in a detectable change in temperature. When the
actuator stops in the range 98 to 100% (the actuator is consid-
ered to be open), a test shall be performed where SAT is ex-
pected to be approximately equal to OAT. If SAT is not deter-
mined to be approximately equal to OAT, a "damper not modu-
lating" alert shall be logged.
Range=50-100
Default=85
Range=0-10
Default=4
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