Dhw Loop Demand And Rate (Hydronic Only); Domestic Hot Water Function - CleaverBrooks CFC Operation, Service & Parts Manual

DHW Loop Demand and Rate
(Hydronic only)
The Domestic Hot Water (DHW) Demand and Rate source
compares a sensor to a setpoint.
A Burner demand will exist if the sensor temperature falls
below the setpoint minus a hysteresis value. Once the burner
demand signal is on, it remains on until the sensor temperature
DOMESTIC HOT WATER
(DHW )
INLET (S1)
OUTLET (S3S4)
DHW (S6 ONLY)
DHW (S6S7)
DATA SERVER "DSD DHW TEMP"
EnviraCOM TOD
TOD
PLATE PREHEAT
SETPOINT
SETPOINT
TOD
SETPOINT
The DHW loop's ability to override the normal demand priority
is described in the System Operation Settings section.
Otherwise the behavior of each parameter and feature is given
below.
S6 (DHW TOP)
DHW ENABLE
EnviraCOM REMOTE STAT
DATA SERVER "DSD DHW DEMAND"
DHW
MODULATION
SENSOR
TOD
T
IF PREHEAT IS ACTIVE,
USE PREHEAT HYSTERESEIS
PREHEAT
ACTIVE
T P
T=x P=1
T=0 P=0
T=1 P=0
TO/FROM
DHW STORAGE
PASS-THROUGH IF PRIORITY<>
DHW STORAGE
Fig. 14. Domestic hot water function.
is above the setpoint plus a hysteresis value, or until the other
selected demand source input (i.e. Remote Stat or DHW
Switch), if any, turns off.
Pump demand may be driven by the a remote stat, or by the
sensor alone.
A Proportional-Integral-Differential controller operates to
generate the source's requested modulation rate.
The DHW function is implemented as shown in Fig. 14.
DHW DEMAND SWITCH
J7-3 120 VAC
SENSOR IS SHORTED
STAT
STAT2
T
NO DATA
TIMEOUT:
REVERT
TO OFF
DHW PLATE DEMAND
PREHEAT
ACTIVE
SENSOR ONLY
HYSTERESIS
BURNER
STATE: ON/OFF
TIME SINCE:
BURNER TURN-ON
BURNER TURN-OFF
NORMAL PREHEAT
ON HYST. ON HYST.
OFF HYST. OFF HYST.
PREHEAT
ACTIVE
PID
0%
P-GAIN
I-GAIN
RESTART (RESTART
INTEGRATOR WHENEVER
A LIMIT OR OVERRIDE
D-GAIN
ENDS, OR TURN-ON
OCCURS.)
33
DATA SERVER DHW OUTPUT ENABLE
SAVE DHW TEMP AND DHW
DEMAND IF THIS IS ENABLED AND
T
THEY ARE NOT ALREADY COMING
FROM THE DATA SERVER
DATA SERVER "DSS DHW DEMAND"
DATA SERVER "DSS DHW TEMPERATURE"
DHW BURNER
SETPOINT DEMAND
DHW HIGH
LIMIT ACTIVE
(SUSPEND DHW DURING
DHW HIGH LIMIT CONDITION)
(USE MIN MODERATION AND ALSO
RESTART THE PID INTEGRATOR AT
THE END OF PREHEATING)
DHW FIRING RATE
SENSOR
TERMINALS
INPUT OUTPUT
DHW STORAGE
PARAMETER
"pRATE" =
0 TO 99.99% OF CAPACITY
CB FALCON
DHW HEAT
DEMAND
DEMAND
750-265