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1
Service
(continued)
Maximum Cascade Cond and Non-Cond Set point (F)
These types of parameters determine the set point used
by the individual boilers in a Cascade. When a boiler is
commanded to fire by the Leader boiler, it will attempt to
achieve this temperature at its outlet. If any of the boiler
outlet temperatures reach the maximum cascade set point,
the boiler will then modulate down on its own in order to
keep its outlet temperature within the maximum cascade set
point. Therefore, these parameters can be used to limit the
outlet temperatures of all the boilers in a Cascade. Note that
these parameters do not apply when the boiler is heating an
indirect DHW tank.
Blocking Time Switching Boiler On / Off
In order to prevent units in a Cascade from short cycling,
this parameter defines the minimum ON and OFF time for
each unit. The installer can adjust this time by accessing the
Blocking Time Switching Boiler On / Off parameter.
Minimum Next On Time
In order to reduce the risk of temperature overshoot with
a Cascade, this parameter defines the minimum time delay
from starting one unit until the next unit may be started.
Number of Boiler Pumps Always On
When multiple Crest boilers are connected in a Cascade, the
SMART TOUCH control can keep a minimum number of
the boiler pumps running, regardless of how many of the
boilers are firing. This is useful in full flow systems where
the system flow is provided by the individual boiler pumps.
Rate % to Switch on Next Boiler
When the Cascade is programmed in the Efficiency
Optimization Mode, the currently running boilers must
ramp up to a certain firing rate before the next boiler in the
Cascade will start.
Figure 1-15A Cascade Redundant Leader Selected
Rate % to Switch off Last Boiler
When the Cascade is programmed in the Efficiency Optimization
Mode, the currently running boiler will stop at this rate.
Member Size Code
The member size code parameter is used to determine the
maximum power and priority of legacy boilers (i.e., Power-
fin) in cascade with the Crest Boiler. The default value for this
parameter is 0. When this value is left unchanged, the SMART
TOUCH control will automatically assume that any member(s) of
the Cascade not communicating their size will be 1,500,000 Btu.
The lowest priority will always be given to these units because the
SMART TOUCH control will assume they are non-condensing
boilers. Changing this parameter is not necessary for Cascade
operation. However, the installer can adjust this code by using
the PC program. The PC program will calculate the proper code
based on the information provided.
Redundant Leader
Th is parameter allows the Member 1 boiler to automatically
assume control of the Cascade should it lose communication
with the Leader boiler. When programmed to YES, it is
recommended that the Member 1 boiler have its own set of
external sensors installed (such as the system supply sensor), to
maintain the same level of temperature control as with the Leader
boiler. Voltage signals (such as the 0 - 10V system pump speed
input) can be connected to both boilers. DO NOT connect the
sensors connected to the Leader boiler to the Member 1 boiler.
Th e actual water temperatures will be higher than expected,
which could lead to property damage, personal injury, or death.
When communication is re-established with the Leader boiler,
Member 1 will automatically relinquish control of the Cascade
to the Leader boiler. Th e default value of this parameter is NO.
Service Manual
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