CleaverBrooks CFC User Manual

750-265 20
Fig. 4. Demand and rate selection diagram.
The demand priority control block shown in Fig. 4 determines
which source of demand has control of the R7910A burner,
according to parameters and the logic described below.
The DHW priority timer within this block operates according to
the logic:
Fig. 5. DHW priority timer logic.
The burner demand priority control block implements a priority scheme according to the descriptions of the parameters shown as
providing input to this block. The implementation is:
ANTI-CONDENS...
BOOST:
“mRATE” = ANALOG% OR RPM
PARAMETER
SENSOR
“pRATE” = 0 TO 99.99% OF CAPACITY
INPUT
OUTPUT
TERMINALS
DELTA-T ...
STACK LIMIT ...
SLOW START ...
REDUCE:
ANTI-CONDENSATION
PRIORITY
STACK
CH BURNER DEMAND
DHW BURNER DEMAND
LL SLAVE DEMAND
BURNER DEMAND
BURNER DEMAND
BURNER STATUS
COMMANDED RATE
ANALOG PERCENTAGE
OUTPUT
MIN/MAX FAN
SPEED LIMIT
MIN PWM
LIMIT
MIN. MOD. RATE
MAX. MOD. RATE
ABS. MIN. RATE
ABS. MAX. RATE
FAN SPEED
RAMP
CH RATE
DHW RATE
LL SLAVE RATE
RATE LIMITS
RATE OVERRIDE
OVERRIDE
LIMITS
FIRING RATE
PWM
4-20mA
0-10V
INLET
OUTLET
FROST BURNER DEMAND
FROST PROTECTION RATE
DEMAND
PRIORITY
CONTROL
DHW ENABLE
CH ENABLE
PRIORITY: CH <>DWH LL<>DHW
pRATE TO mRATE
CONVERSION
TOP: FIRING & BC HAS NO COMMANDED RATE & ONE OF THE MANUAL MODES IS ENABLED.
OR
NOT FIRING & BC IS IN STANDBY & “MANUAL IN RUN & STANDBY” IS ENABLED.
MIDDLE: NOT ABOVE AND BC HAS A COMMANDED RATE (E.G. IN STANDBY, PURGE, IDNITION, ETC.)
BOTTOM: FIRING & BC HAS NO COMMANDED RATE & AUTO MODE SELECTED (NORMAL MODULATION)
OFF (NO DEMAND) = 0
OFF (NO DEMAND) = 0%
DHW
DEMAND
PRIORITY
TIMER
CH PUMP DEMAND
DHW PUMP DEMAND
SLAVE COMMAND EXISTS
CH FROST PROTECT BURNER DEMAND
LL SLAVE ENABLE
DHW FROST PROTECT BURNER DEMAND
DHW FROST PROTECTION ENABLE
RELOAD
CH
DHW
LL
FP
OFF
CH
DHW
LL
FP
OFF
0
=
BC HAS COMMANDED FAN TO BE OFF & NOT BELOW; OR BC DISABLED/FAULT.
=
MANUAL RATE WHEN FIRING IS LESS THAN MINIMUM MODULATION,
OR ABNORMAL BC REQUEST (MANUAL MODES IGNORED).
=
MANUAL RATE WHEN FIRING IS GREATER THAN MAX MODULATION.
=
ABNORMAL BC REQUEST OR MANUAL IN STANDBY IS LESS THAN ABS. MIN.
=
ABNORMAL BC REQUEST OR MANUAL IN STANDBY IS LESS THAN ABS. MIN.
TACH
PUMP
CONTROL
BURNER
CONTROL
MODULATION
OUTPUT
MIN. MOD. RATE
FORCED RATE...
M24973
DHW PRIORITY OVERRIDE TIME
CH FROST PROTECTION ENABLE
MANUAL RATE ENABLE
- AUTO
- MANUAL IN RUN
- MANUAL IN RUN AND STANDBY
MANUAL
RATE
SELECT
M24971

CleaverBrooks CFC Specifications

General

Brand	CleaverBrooks
Model	CFC
Category	Boiler
Language	English