CleaverBrooks CFC-500 Operation, Service And Parts Manual page 174

CB FALCON
Anticondensation (Hydronic Control)
The anticondensation function reduces condensation effects
when the temperature is below a threshold by increasing the
firing rate and optionally shutting off the pump.
Anticondensation operates only when the burner is firing, and
is active only if enabled for the demand source (i.e. CH, DHW)
currently controlling the burner.
Parameter
CH anticondensation enable
CH anticondensation setpoint
DHW anticondensation enable
DHW anticondensation setpoint
Frost protection anticondensation
enable
Anticondensation Priority
Modulation Output
The modulation output subsystem uses as its input either the
modulation rate provided by the Internal Demand/Rate
Selector, which possibly is limited by a Rate Limit function, or it
uses a fixed modulation rate indicated by the burner control,
such as during prepurge or lightoff, or it uses a manual rate.
Fig. 5 in "Demand and Rate" on page 22 shows these sources.
The modulation output subsystem sends a rate to one of three
outputs: a fan speed control that uses a PWM output and
tachometer feedback, a 4-20 mA analog signal, or a 0-10 V
analog signal.
750-265
Table 25. Anticondensation Parameters.
Enable, Disable
This parameter enables or disables anticondensation for CH and LL demand.
Degrees or None
If CH demand anticondensation is enabled, and if CH demand or LL slave demand is in
control of the burner, and the burner is firing, and if the temperature of the outlet sensor is
below the temperature given by this parameter:
then the anticondensation subsystem requests the burner's firing rate to be set to the rate
given by the CH maximum modulation rate. Whether this succeeds or not depends on the
priority of anticondensation compared to other rate-reducing limits (as described at the
beginning of "Rate Limits and Override" on page 43).
When the CH source sensor temperature reaches or exceeds the temperature given by this
parameter plus a fixed hysteresis value or 4°F then this rate limit ends.
Enable, Disable
This parameter enables or disables anticondensation for the outlet sensor when the DHW
loop is in control.
Degrees or None
If DHW demand anticondensation is enabled, and if DHW demand is in control of the burner,
and the burner is firing, and if the temperature of the outlet sensor is below the temperature
given by this parameter:
• Then the anticondensation subsystem requests the burner's firing rate to be set to the rate
given by DHW maximum modulation rate. Whether this succeeds or not depends on the
priority of anticondensation compared to other rate-reducing limits (as described at the
beginning of "Rate Limits and Override" on page 43).
• When the outlet sensor temperature reaches or exceeds the temperature given by this
parameter plus a fixed hysteresis value or 4°F then this rate limit ends.
Enabled, Disabled
When Frost Protection is in control, either the CH or DWH anticondensation function is
enabled.
Anticondensation is more important than (check those that apply):
Stack limit
Delta T limit
Slow start
Forced rate
Outlet high limit
The pump corresponding to that source will usually be on;
however, to warm the heat exchanger more quickly, that pump
may be forced off when anticondensation is active.
The anticondensation parameters are as follows:
Comment
When the installer selects a fan speed system, rate parameters
will be specified in RPM without regard to the burner capacity
represented by a particular RPM. When one of the analog
outputs is chosen, rate parameters will be specified as
percentages, and in this case, the installer typically is thinking
of this as a percent of burner capacity.
Common Modulation Parameters
These parameters are needed whenever any type of
modulation is used.
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