Carrier 16DF013-050 - Manual (Page 29)

Abnormal Shutdown (Fig. 26 and Table 10)
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During operation, various conditions are monitored by
the control system to protect the machine and to ensure safe
operation. When any of these conditions exceed their nor-
mal safe operating limit, the machine will be shut down au-
tomatically and the audible alarm on the front of the control
panel will buzz.
The cause of the limit shutdown will be displayed in code
by the 3-character indicator on the front of the control panel.
These are listed in Table 7. The alarm can be silenced by
depressing the Stop button, after the cause of the shutdown
has been noted. This will reset the control circuit for a restart
after the shutdown sequence has been completed and the cause
of the shutdown has been corrected. Combustion failures are
also indicated by an alarm light on the burner panel. A com-
bustion failure can be reset by pressing the reset button on
the burner combustion controller in the burner control panel.
Some conditions will allow the burner to first modulate to
the minimum firing position for a normal low-fire shutdown.
Others will close the fuel valve immediately. Most of the
conditions will allow a normal dilution period before shut-
down, but several will stop the machine immediately with-
out dilution. The latter conditions should be corrected as quickly
as possible to allow a restart or manual dilution before so-
lution crystallization occurs.
The shutdown follows the typical cooling or heating stop
sequence, with the immediate combustion stop or lack of di-
lution exceptions as listed. Also with low chilled water tem-
perature or flow, the dilution cycle is delayed until after the
cooling tower fan and cooling water pump are stopped.
Fig. 26 — Abnormal ‘‘Stop’’ Flow Chart
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