KMC Controls FlexStat Operation Guide - Manual (Page 35)

FlexStat 35 Operation Guide, Rev. R
Also check that its leads are not pinched, shorted,
or broken and that the tape holding down the
leads is not loose. (Some early models with
humidity sensors did not have the additional
thermistor—temperature was derived from the
same chip that measured humidity.)
• Using BACstage or TotalControl, check that
AI1 (space temp.) is not configured as “Out Of
Service.”
• Check that the FlexStat is NOT mounted on an
exterior wall, mounted on or near a large thermal
mass (e.g., concrete block wall), blocked from
normal air circulation by obstructions, exposed
to heat sources (e.g., lights, computers, copiers,
coffee makers) or to sunlight (at any time of the
day), exposed to drafts from windows or air
vents, or exposed to air flow through the conduit
from leaks in plenum ducts (put plumber’s putty
or other sealant inside conduit to block air leaks).
• See also Input Values Are Outside the Expected
Range on page 34 .
Temperature Setpoint Is Not Maintained
• Select Occupied mode from the Home Menu—
see H/C, Fan, Occupancy, and Override on page 4 .
• Override the fan to On from the Home Menu—
see H/C, Fan, Occupancy, and Override on page 4 .
• Check that the appropriate application is select-
ed—see (Advanced) Application and Additional
Setup on page 7 .
• Check that room temperature is being sensed
correctly—see Temperature Reading Is Incorrect
on page 34 .
• If space temperature is overshooting the setpoint
or oscillating, try increasing the proportional
band by a degree. If the problem persists, try
increasing the integral value slightly (up to
20%). If the problem still persists, try setting the
integral value to 0. (The optimal integral value is
dependent on the characteristics of the particular
space and HVAC system.) See (Advanced) PID
Loop Configuration on page 18 .
• In 2-pipe FCU applications, check the changeover
water temperature sensor and wiring.
• If the HVAC system has trouble recovering
from the unoccupied setpoint to the occupied
setpoint during very cold weather, enable/adjust
the setback lockout. See Setback (OAT) Lockout
Setup on page 10 .
Time and/or Date Are Not Correct
NOTE: When a FlexStat is powered up after
losing the RTC (Real Time Clock) time, it
will revert to the default time and date of
January 1, 2000, 12:00:00 AM.
• Set time and date in the menu. See Date/Time on
page 23 and/or (Advanced) Date/Time on page 16 .
• Check the DST (Daylight Saving Time) settings.
See (Advanced) Date/Time on page 16 .
• Using BACstage or TotalControl, send a time
synchronization command.
NOTE: An issue can occur if a FlexStat has been un-
powered long enough for it to lose its RTC
timekeeping during the period DST (Day-
light Saving Time) is in effect (currently
the second Sunday of March through the
first Sunday of November) and a time syn-
chronization command is sent from BAC-
stage or TotalControl to the FlexStat. The
time will be restored to the correct time and
date. However, the FlexStat will assume
that this time is non-DST. Within about one
minute after the initial time synchronization
(during DST months), the device time will
reset to DST mode, and the device time will
move one hour ahead. This will affect the
displayed time on the LCD display as well
as any schedules. This issue will not affect
newly powered FlexStats during non-DST
periods (e.g., most of November through
February). If the time has erroneously ad-
vanced one hour after an initial time synch
command, the easiest solution is to simply
send a second time synch command. This
will correct the device time. Alternately, the
hour can be changed in the FlexStat’s menu.