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OPERATING STAGING BOILER SETTINGS
REACTION TIME
Adjustable from 1 to 10 minutes
Button: MENU/<System Settings>/<More Settings>/<Stage Settings>/
Reaction Time
•
It is the amount of time it takes a single stage to affect the system.
•
After the Mini-MOD-CNC turns on a stage trying to meet a set point, it will not turn on
another stage until the Reaction Time has elapsed.
•
To determine the optimum time, start with a hot system. Then, turn on a single stage and
calculate how long it takes until the system begins to respond to that stage. That period
should be set as the Reaction Time.
MINIMUM RUNTIME
Adjustable from 1 to 60 minutes
Button: MENU/<System Settings>/<More Settings>/<Stage Settings>/
Min Runtime
•
This is the minimum amount of time any stage will run.
•
For the lowest stage of a unit, the Minimum Runtime starts after the purge cycle.
•
The Runtime does not apply to the last stage online. The Last Stage Hold applies in
that case.
•
Initially, set the Minimum Runtime to half the Reaction Time.
•
If the system tends to overshoot, reduce the Minimum Runtime. However, if boilers tend
to short cycle, increase the Minimum Runtime.
AVOIDING CONFLICTING BOILER LIMITS
•
The temperature limits set on the boilers MUST be set considerably higher than the
Mini-MOD-CNC's Set Point for the reasons detailed below.
•
The Mini-MOD-CNC sensor is located in a common header some distance from
the boilers.
•
As the temperature rises in the header and before reaching the sensor location, energy
is dissipated. Therefore, the temperature in the header could be lower than that
registered by boiler sensors.
•
In addition to the normal drop experienced between the boiler's temperature and that
read by the Mini-MOD-CNC sensor, the Last Stage Hold setting must be accounted for.
The boiler limit must be set above the Set Point PLUS the Last Stage Hold PLUS the
normal drop experienced in the piping.
•
Using the previous example of a 10°F Last Stage Hold with a 160°F Set Point, the
boilers' limits must be set enough over 170°F to prevent the boilers' internal limits
being reached. In this situation, the boiler high limit should be set at approximately
180°F or higher to prevent the difference in boiler temperature vs. header temperature
causing erratic operation.
059102-00 REV. C
14 OPERATING MENU SEQUENCE
Default: 2 minutes
Default: 2 minutes
STAGE SETTING
Reaction Time
2min
Minimum Runtime
2min
BACK
REATION TIME
2 min
BACK
MINIMUM TIME
2 min
BACK
SAVE
WARNING
The temperature limits
set on the boilers must
be higher than the
Mini-MOD-CNC Max
Water Temp. Read the
section at left for details
that will prevent erratic
system operation.
HEAT-TIMER CORP.
SAVE
SAVE
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