Page 17
Calibration Mode Sequence
Occurs after power up, after cooling operation, or if the coil temperature exceeds the termination
temperature while in Heat Mode.
DCB defaults to 34 minutes Time/Temperature Mode
Reset Compressor Runtime / Reset Three / Five Strike Counter
DEMAND MODE
Accumulate compressor run-
time while coil temperature
is below 35° F (2°C). When
the accumulated compres-
sor time exceeds 6 hours or
if the coil sensor indicates
frost is present on coil, go to
Defrost.
34 MIN. TIME/TEMP. MODE
Accumulate compressor run-
time while coil temperature
is below 35° F (2°C). When
the accumulated compressor
time exceeds 34 minutes go
to Defrost.
45 MIN. TIME/TEMP. MODE
(90 min for −1 to −4 boards)
Accumulate compressor run-
time while coil temperature is
below 35° F (2°C). When the
accumulated compressor
time exceeds 90 minutes go
to Defrost.
DEFROST
OUTDOOR FAN Off
Reversing Valve ON
W1 line ON
Monitor coil temperature
and time in defrost mode.
HOW DID DEFROST TERMINATE?
Coil temperature was
above 35°F (2°C) for 4
min. of the 14 min. de-
frost OR reached defrost
termination temp.
DCB’s 60L3901 and 46M8201
LO−PS Termination Option
selected. Defrost terminated by
pressure.
Defrosted for 14 min. with-
out the coil temp. going
above 35°F (2°C) for 4
min and coil did not reach
termination temp.
At termination of defrost the compressor
runtime counter is reset/Turn on Outdoor
FAN /Rev Valve & W1 turn off.
At Termination of Defrost
the compressor runtime
counter is reset/Turn on
Outdoor FAN/Rev valve &
W turn OFF
Attempt to Calibration−Temperature measurements are not taken
for the first few minutes of each heat demand. This is to allow coil
temperatures to stabilize. DCB has a maximum of 20 minutes of
accumulated compressor runtime in heat mode to calibrate DCB
This may involve more than one heating demand.
YES, calibration occurred
Was stable coil temp. attained
within 20 minutes?
NO, DCB reverts to 45 min. (90
min. for −1 to −4 boards) time/temp.
FIGURE 19
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