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Servicing should only be performed by a Quali
fi
ed Service Technician
Max Setpoint
This parameter determines the set point used by the individual water heaters in a Lead/Lag. When a water
heater is commanded to
fi
re by the Leader water heater, it will attempt to achieve this temperature at its outlet.
The Leader water heater will limit the modulation of the water heaters in order to hold the temperature at the
tank sensor to the user set point. If any of the water heater outlet temperatures reach the maximum Lead/Lag
setpoint, the water heater will then modulate down on its own in order to keep its outlet temperature within
the maximum Lead/Lag setpoint. Therefore, this parameter can be used to limit the outlet temperatures of all
the water heaters in a Lead/Lag. This parameter is adjustable by the installer by accessing the Max Setpoint
parameter under the Control Modes and then Lead/Lag. The temperature range of this parameter is 32°F
(0°C) to 190°F (88°C). The default maximum setpoint is 185°F (85°C).
Min On/Off Time
In order to prevent units in a Lead/Lag from short cycling, this parameter de
fi
nes the minimum ON and OFF
time for each unit. The installer can adjust this time by accessing the Minimum On/Off Time parameter. The
minimum setting is 0 seconds and the maximum setting is 10 minutes. The default is 30 seconds.
Min Next On Time
In order to reduce the risk of temperature overshoot with a Lead/Lag, this parameter de
fi
nes the minimum
time delay from starting one unit until the next unit may be started. The installer can adjust this time delay
by accessing the Minimum Next On Time parameter. The minimum setting is 0 minutes and the maximum
setting is 10 minutes. The default is 60 seconds.
DHW Size (Slave X)
When water heaters of different sizes are connected together in a Lead/Lag, the Leader water heater has
to know the size of each heater in that Lead/Lag. The water heater size parameters allow the installer to
program the sizes based on the Lead/Lag address. This screen shows the Lead/Lag address and the size of
the water heater with that address (in BTU/hr):
The UIM control automatically uses the Ef
fi
ciency Enhancement Lead/Lag type when controlling water
heaters of different sizes.
ECONOMY MODE/CLOCK
Time and Date
The control uses an internal clock for the night setback feature and for logging of events. For these features
to work correctly, the clock must be set when the water heater is
fi
rst installed or anytime the water heater has
been powered off for more than four (4) hours. This parameter must be accessed to set the clock.
Note:
The internal clock does not adjust for Daylight Savings Time and therefore, will require a manual
adjustment.
Setpoint Adjustment
Once the unit’s internal clock has been set correctly, the Setpoint Adjustment feature can be used to program
a lower setpoint during unoccupied times. The DHW can be programmed for night setback. When in night
setback, the control reduces the set point by a
fi
xed amount. For DHW, it subtracts the DHW Setpoint
Adjustment offset from the tank set point (Tank Set point parameter).
Note:
The DHW Setpoint Adjustment will not work without a tank sensor installed.
The installer may adjust the Setpoint Adjustment by accessing the Economy Mode parameter. The minimum
setting is 0°F (0°C) and the maximum setting is 90°F (50°C).
Start Time X/ Stop Time X
This is the time in which the Setpoint Adjustment becomes active. There are 7 start times and 7 stop times
each for the DHW night setback feature. The DHW Night Setback On Times may be set to any time within
a 7-day week. These settings are referred to as triggers. Multiple start or stop triggers may be set within a
single day, if desired. When a start trigger and a stop trigger are set to the same time, the stop trigger has
priority. The installer may adjust the DHW start triggers in the Start Time/ Stop Time parameter. This screen
shows the start trigger number, the day of the week, and the time of day.
