CleaverBrooks CFC-500 Operation, Service And Parts Manual page 151

Parameter
CH ODR low outdoor
temperature
CH ODR boost time
CH ODR boost max burner off
point
CH ODR low water temperature
CH ODR maximum outdoor
temperature
CH ODR boost step
CH ODR boost recovery step
time
Minimum boiler water
temperature
If CH outdoor reset is not active or if the CH ODR boost time
parameter is zero, then the boost function is inactive.
Otherwise, the boost time provides a time interval and the
other parameters must be valid—if they are not, the boost
function is inactive and an alert is issued.
Each time the boost time interval elapses and CH demand is
not satisfied, the effective CH setpoint is increased by the
amount specified in CH ODR boost step. However, CH ODR
boost max setpoint limits this action: it is never exceeded.
180
(min outdoor, Setpoint)
160
140
step °F
120
100
80
60
40 (min outdoor, TOD Setpoint)
0 20 40
OUTDOOR TEMPERATURE
Fig. 9. Outdoor reset with TOD and boost.
Table 9. Outdoor Reset and Boost Parameters.
Degrees or None
This parameter determines the X coordinate of one point on the ODR graph. At that outdoor
temperature, the setpoint will be the CH setpoint (or the CH TOD setpoint, if TOD Is on).
mm:ss
Degrees or None
If CH outdoor reset is not active or if the CH ODR boost time parameter is zero, then the
boost function is inactive.
Otherwise, the boost time provides a time interval. Each time this interval elapses and
demand is not satisfied, the setpoint is increased by 18°F, up to the maximum provided by the
CH ODR boost max burner off point. However, if the latter is not valid, then the boost function
is inactive and an alert is issued.
Degrees or None
These two parameters determine one point on the ODR graph. At the maximum outdoor
temperature, the setpoint will be the low water temperature.
Degrees or None
mm:ss
Degrees or None
Defines the minimum outdoor reset setpoint for the stand-alone CH loop if this is invalid or
none, then outdoor reset is inhibited and will not run. If enabled an alert is issued.
Should be higher than setpoint
Boost max setpoint
(max outdoor, min water)
60 80
Comment
Once the demand is satisfied the boosted setpoint remains
active and slowly returns to its non-boosted level according to
the CH ODR boost recovery step time. Whenever this interval
elapses, the setpoint is adjusted back toward its normal value
by 0.5°C (0.9°F).
If the TOD switch changes state after at least one boost event
has occurred, the new effective setpoint is the higher of:
• the old boosted setpoint and
• the new unboosted setpoint.
However, if the first boost event has not yet occurred, then the
new setpoint is adopted immediately. In either case, the boost
timer—which began when the demand started and continues
to measure the boost time interval—is not reset when TOD
changes state.
27
CB FALCON
750-265