CleaverBrooks CFC-500 Operation, Service And Parts Manual page 160

CB FALCON
DHW MODULATION SENSOR
DHW
TRUE WHILE
DROPPING FASTER THAN
TAP DETECT DEGREES PER SECOND
DHW
TOD SELECT
TRUE IF DHW <= SETPOINT-
TAP DETECT ON HYSTERESIS
AND THIS PERSISTS FOR LONGER THAN:
TAP DETECT RECOGNITION TIME
DHW
INLET (S1) INLETTEMP
TRUE IF INLETTEMP-DHW =>-
TAP STOP INLET -DHW DEGREES
INLETTEMP
OUTLETTEMP
OUTLET(S3S4)
TRUE IF OUTLETTEMP-INLETTEMP<=
TAP STOP OUTLET -INLET DEGREES
DHW PLATE DEMAND
Parameter
Tap detect degrees per second
Tap detect on hysteresis
Tap detect on recognition time
Tap detect on threshold
750-265
DHW IS
SETPOINT
TOD SETPOINT
TIMER
PLATE PREHEAT ON HYSTERESIS
PLATE PREHEAT SETPOINT
PLATE PREHEAT OFF HYSTERESIS
PLATE PREHEAT ON RECOGNITION TIME
PLATE PREHEAT DELAY AFTER TAP
PLATE PREHEAT MINIMUM ON TIME
Fig. 15. Plate heat exchanger subsystem.
Table 12. Plate Heat Exchanger Parameters.
Degrees or None
This tap demand "set" criteria depends on rate of change of the DHW sensor. The rate of
change of this temperature is monitored. If it falls at a rate faster than specified degrees per
second then the Tap demand block is "Set" (Tap demand becomes true and the minimum on
timer is started).
Degrees or None
The second tap demand "set" criteria depends on the value of the DHW sensor. If the
temperature is less than or equal to the threshold given by subtracting this parameter from
the normal DHW setpoint, and if this condition has persisted for the time specified by the Tap
detect recognition time parameter, the Tap demand block is "Set" (Tap demand becomes true
and the minimum on timer is started).
The timer that measures the Tap detect recognition time resets if the temperature rises above
the threshold and a new Tap detect event will not occur again until the threshold has again
been met or exceeded (on the low side) for the recognition time.
hr:mm:ss or None
This provides the time for a Tap detect event due to the Tap detect on hysteresis, as
described just above.
-17 °C to 82 °C (-0 °F to 180 °F)
WHENEVER SET CHANGES FROM OFF TO ON,
TAP OUTPUT IS TRUE FOR AT LEAST THE
TAP DETECT MINIMUM ON TIME
TAP DEMAND ENDS WHEN:
TIMER
•TIME IS EXPIRED, AND
SET LOAD
•SET IS FALSE, AND
•CLR IS TRUE
IF FORCE IS ON, TREAT AS IF BOTH SET AND
IF SET HAD JUST CHANGED CLR ARE TRUE,
FROM OFF TO ON. IGNORE CLR
FORCE TAP
CLR
DHW FORCE TAP PREHEAT
WHENEVER PREHEAT IS FALSE:
IF TAP IS TRUE, INHIBIT THIS PREHEAT BLOCK, RESET THE
ITEMS, AND RESET THE PREHEAT DELAY-AFTER-TAP TIMER.
IF TAP IS FALSE, ALLOW THE TIMER TO RUN.
IF PREHEAT IS FALSE, IT BECOMES TRUE WHEN:
•TAP IS FALSE
•THE PREHEAT DELAY-AFTER-TAP TIME HAS ELAPSED
• DHW <= PREHEAT (SETPOINT-ON HYSTERESIS)
•THE ABOVE HAVE PERSISTED FOR THE ON RECOGNITION TIME
WHEN PREHEAT TURNS ON, ITS MINIMUM ON TIME IS STARTED
IF PREHEAT IS TRUE, IT BECOMES FALSE WHEN:
•TAP DURING PREHEAT IS RECOGNIZED (SEE BELOW)
•BOTH: • DHW <= PREHEAT (SETPOINT+OFF HYSTERESIS)
INLET
• PREHEAT MINIMUM ON TIME HAS EXPIRED
•TAP DURING PREHEAT IS RECOGNIZED AS:
• TAP HAS BEEN TRUE WHILE PREHEAT WAS TRUE
• EITHER • INLET TEMPERATURE DECREASES BELOW THE LEVEL
IT HAD WHEN PREHEAT STARTED
• DHW >= INLET
WHEN THESE HAVE OCCURRED, THEN A 1 MINUTE TIMER STARTS.
WHEN THIS TIME ELAPSES, THEN PREHEAT ENDS. THE FORCE OUTPUT IS PULSED
TO FORCE TAP DETECTION TO START (AND PREHEAT IS INHIBITED). THIS ALSO
OCCURS IMMEDIATELY IF THE 1 MINUTE TIMEOUT IS PENDING BUT PREHEAT
ENDS DUE TO ABOVE.
Comment
36
PRIORITY
IS
TAP
DHW
IF DHW PLATE
DEMAND LOSES
CONTROL DUE TO
PRIORITY, RESET AND
RESTART THE
OTHERS CONTINUE TO
OPERATE.
TAP
DHW
PLATE
PREHEAT
DEMAND
PREHEAT IS ACTIVE
PREHEAT
TIMER
FLAG
AND
OR
TIMER
ITEMS.
TIMER
AND
AND
AND
TIMER
OR
AND