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SEQUENCE OF OPERATION
1. When the reset is enabled, the Y-Series Control continously monitors outdoor temperature using the outdoor
temperature sensor. When the outdoor temperature falls below the outdoor cutoff tempersture, the Control becomes
active and closes the primary pump relay, energizing the primary system circulating pump. The Control then monitors
the system supply water temperature. The microprocessor calculates an optimum target water temperature within
selectable limits of the control band, the setpoint, the reset ratio and the outdoor air temperature. If outdoor is reset is
disabled, the readings of the air sensor are not used in subsequent calculations. In either case, if the water temperature
falls below the the calculated target temperature the Control sends a call for heat to the lead unit (stage).
2. Upon a call for the heat the control closes the lead unit's thermostat (TH) circuit, which the energizes the lead unit's
circulating pump. After the flow switch has confirmed adequate flow, the ignition sequence is initiated and the unit
ignites at stage 1. The Control then sequences the units/stages in response to changes in the system to target differen
tial temperature, time away from target temperature, and temperature rate-of-change parameter as determined by the
P+I+D algorithems.
3. Additional stages (and units) are activated or deactivated as required in order to maintain or restore target system
water temperature. This Control uses "first on, last off" logic. As the system water temperature increases and begins to
approach target temperature, the Control deactivates the stages and heaters in reverse order of firing until the first
unit/stage fired is turned off. After the final stage of a given unit has been turned off, that unit's Economaster pump
control will continue to power the unit's circulating pump until a user-adjustable time delay has elapsed, thereby
extracting all available residual heat.
4. The Control stores firing command and system response data in the last five memory registers of the microprocessor.
On the next call for heat, the Control will modify the stored P+I+D data to optimize its own responses.
5. When the outdoor temperature exceeds the outdoor cutoff temperature, the Control enters warm weather shut-down
mode. The primary pump is turned off after a user-adjustable time delay, and the Control becomes dormant, until
outdoor temperatures again fall below the outdoor cutoff temperature.
MANUAL OVERRIDE
Internal Switch (S5) Output Override can be used to manually override the Micro-controller control as long as the
Electronic Boiler Control circuit board has 24 VAC power. See Output Over-Ride Switch (S5) above.