CleaverBrooks CFC-500 Operation, Service And Parts Manual page 155

Whenever the burner turns off, the turn-on threshold is lowered
by doubling the on hysteresis, and then increasing it by 2
degrees F per step until it reaches its original value.
The time of each step is provided by the hysteresis step time
parameter. The number of steps required to reach the original
on hysteresis is the on hysteresis value divided by
2 degrees F.
Step Time since turn-on Hydronic Turn-on threshold
1 0<=timer <1T
2 1T<=time <2T
3 2T<=time <3T
4 nT<=time <(n+1)T
5 (on hysteresis/
2F*T<=time
CH PARAMETERS DHW PARAMETERS
OFF HYST.
SETPOINT
TOD SETPOINT
ON HYST.
HYSTERESIS STEP TIME HYSTERESIS STEP TIME
1 MINUTE
SETPOINT - ON HYSTERESIS
ON
BURNER
OFF
ANTI-SHORT-CYCLE DELAY
Fig. 12. Hydronic Setpoint and hysteresis.
Setpoint - 2 * On hysteresis
Setpoint - 2 * On hysteresis +
1*2°F
Setpoint - 2 * On hysteresis +
2* 2°F
Setpoint -2 * On hysteresis + n
* 2°F
Setpoint
LL MASTER PARAMETERS
OFF HYST. OFF HYST.
SETPOINT SETPOINT
TOD SETPOINT TOD SETPOINT
ON HYST. ON HYST.
HYSTERESIS STEP TIME
SETPOINT AND HYSTERESIS
+18°F
HST = HISTERESIS STEP TIME
+8°F
(0 = DISABLE)
+6°F
+4°F
+2°F
SETPOINT + OFF HYSTERESIS
SETPOINT
1 MINUTE
2°F
SETPOINT - 2 * ON HYSTERESIS
SYSTEM PARAMETER
ANTI SHORT CYCLE DELAY TIME
(DOES NOT APPLY FOR DHW)
Setpoint and Hysteresis (Steam
Control)
The Steam and LL master each have similar setpoint and
hysteresis functions. The parameters for each are separate
and independent.
Whenever the burner turns on, the turn-off threshold is raised
by 10psi (1.0 for 0-15 psi), and then it is decreased in steps.
The time of each step is provided by the hysteresis step time
parameter. If the time (T) is not-zero, then the following
schedule is followed until the off threshold reaches its original
value:
Steam Turn-off Threshold
Step 150psi Sensor
1 10
2 8
3 6
4 4
5 2
6 Setpoint
Whenever the burner turns off, the turn-on threshold is lowered
by doubling the on hysteresis, and then increasing it by 2 psi
(.2 psi for 0-15 psi) per step until it reaches its original value.
The time of each step is provided by the hysteresis step time
parameter. The number of steps required to reach the original
on hysteresis is the on hysteresis value divided by 2 psi per
step for (0–150 PSI .2 psi per step for; 0–15 PSI).
Steam Turn-on Threshold
Step 150psi Sensor
1 0<=timer<1T
2 1T<=time<2T
3 2T<=time<3T
4 nT<=time<(n+1)T
5 (on hysteresis/
2psi<=time)
31
CB FALCON
15psi Sensor
1.0
0.8
0.6
0.4
0.2
Setpoint
15psi Sensor
Setpoint - 2* On
hysteresis
Setpoint - 2 * On
hysteresis + .2psi
Setpoint - 2 * On
hysteresis + .2psi
Setpoint - 2 * On
hysteresis + .2psi
Setpoint
750-265