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P/N 42-9472 Copyright 2008 Mestek, Inc.
Cast iron condensing boiler
Cast iron condensing boiler
— Control manual
The Mestek
200
i
boiler — SmartCycle
TM
control
Control overview
Th e 200i SmartCycle control monitors boiler temperature and limit circuit inputs, modulating boiler fi r-
ing rate to meet demand. Th e control uses microprocessor electronics, watching time-average response
from the system to anticipate how much heat the system needs. Coupled with the fi ve-to-one turndown
of the 200i boiler, this results in maximum possible condensing-mode operation. Th e 200i boiler will
provide unmatched seasonal effi ciency.
Indoor air reset (IAR)
Mestek’s unique approach to boiler output regulation is its Indoor Air Reset function. Th e control moni-
tors the demand from up to 8 diff erent zones. Watching the demand duration and response to supply
temperature, averaging over time, the SmartCycle control anticipates system needs. It sets boiler maxi-
mum fi ring rate and adjusts supply water temperature to fi ne-tune boiler heat output. All that is required
to enable IAR is to connect thermostat circuit wires to the IAR inputs. Th e SmartCycle control can also
be confi gured for outdoor reset operation, but IAR provides response based on system behavior rather
than just looking at outdoor temperature.
The SmartCycle platform
SmartCycle controls are designed to provide an integrated boiler management system on every boiler.
Th e platform provides multiple levels of selectivity. SmartCycle electronics can be operated as a simple
single-boiler control, while still providing intelligent regulation of boiler fi ring rate to match system de-
mand. With a few key strokes on the key pad, the SmartCycle control can operate as a sophisticated
multiple-boiler controller, using simple RJ45 cable interfacing between units. Th e control can even ac-
cept external control commands from building managements systems (Modbus standard, with optional
bridge for BACnet or LonWorks) or 20-milliamp analog input from an external controller.
Th e control method used by the SmartCycle control is based on digital communications, which elimi-
nates the need for analog control signals. Analog signal inputs are supported, but a higher level of control
precision, repeatability and feedback is gained with digital communications.
Th e SmartCycle control can be versatile, providing for operation in multiple ways:
Operation as a stand-alone boiler.
Operation as a boiler in a boiler network, using the on-board SmartCycle protocol.
Operation as a member boiler in a boiler management system.
Operation as a member of a remotely-controlled boiler network (20-milliamp regulation).
Setpoint can be determined by the SmartCycle control or by a 20-milliamp input signal.
PID response
Th e SmartCycle control uses proportional-integral-derivative calculations to determine the response to
boiler water temperature changes. Th is means it not only looks at how far away the water temperature is
from the setpoint temperature, but how fast the temperature is changing and how it has responded over
time. Th is ensures the boiler won’t make sudden unnecessary changes in fi ring rate.
Multiple boiler operation
Th e SmartCycle control easily interfaces with other SmartCycle controls. Multiple boiler operation using
SmartCycle protocol only requires RJ45 cables daisy-chained from boiler to boiler and a few key strokes
sett ing up control behavior. Th e master boiler is automatically selected by connecting a sensor lead to its
HEADER sensor terminals. Th e SmartCycle control recognizes the sensor and confi gures the boiler as
the master. Other boilers only need to have an address assigned.
Among the advanced design features of the SmartCycle control is the MOD-MAX sett ing. Th is limits the
fi ring rate of all boilers to a pre-set maximum (50% by default). Th
is means all of the boilers will be run
at a very effi cient level until all boilers are on. Only then can fi ring rate increase above this sett ing. Boiler
rotation can be fi rst-on/fi rst-off , fi rst-on/last-off , or true rotation (the SmartCycle control monitors the
total on time of all boilers, and rotates their usage so the total on time is the same for all).
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200
i
SmartCycle
Control panel
