User Guide

1 Service (continued)
17
Maximum Cascade Set Point
This parameter determines the set point used by the individual
water heaters in a Cascade. When a water heater is commanded
to fire 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 last water heater to fire 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
cascade set point, the water heater will then modulate down
on its own in order to keep its outlet temperature within the
maximum cascade set point. Therefore, this parameter can be
used to limit the outlet temperatures of all the water heaters
in a Cascade. This parameter is adjustable by the installer by
accessing the Maximum Cascade Set Point parameter. The
temperature range of this parameter is 32° (0°C) to 190°F
(88°C). The default maximum cascade set point is 185°F (85°C).
Minimum On/Off Time
In order to prevent units in a Cascade from short cycling, this
parameter defines the minimum ON and OFF time for each
unit. (This timer is overridden when the call for heat ends.)
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.
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. 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.
Boiler Size
When water heaters of different sizes are connected together in
a Cascade, the Leader water heater has to know the size of each
water heater in that Cascade. The Boiler Size parameters allow
the installer to program the size based on the Cascade address.
This screen shows the Cascade address and the size of the water
heater with that address (in BTU/hr):
1. When the Boiler Size screen is first accessed, Cascade
Address 0 (Leader) is shown.
2. Press the NAVIGATION dial to access the first digit of the
water heater size. Rotate the NAVIGATION dial to adjust
the first digit. To access the next digit, press the
NAVIGATION dial again. Continue this process until the
correct water heater size (to the nearest 1000 BTU/hr) is
shown. Press the RIGHT SELECT [SAVE] key.
3. Rotate the NAVIGATION dial to select the address of the
next water heater in the Cascade. Repeat Step 2.
4. Once the size of the last water heater in the Cascade has been
entered and saved, press the LEFT SELECT [EXIT] key to
return to the Control Modes menu.
5. If no other parameters are to be adjusted, press the RIGHT
SELECT [HOME] key to save the new settings and return
to the Status screens.
The SMART SYSTEM control automatically uses the Efficiency
Optimization Cascade type when controlling water heaters of
different sizes.
Circulation pumps
DHW Pump Delay
The DHW pump delay parameter sets the length of time the
DHW pump (if connected) will run after a DHW demand has
been satisfied. This parameter is adjustable by the installer by
accessing the DHW Pump Delay parameter. The time range
for this parameter is 10 seconds to 40 minutes. The default
time is 1 minute.
DHW Pump Anti-Seize Delay
If the water heater pump does not run for 24 hours, it will
be turned on briefly to prevent it from seizing. The length
of time it runs is determined by the DHW Pump Anti-Seize
Delay parameter. The range of this setting is 0 seconds to 50
minutes. The default setting is 20 seconds.
BMS
BMS Type
When programmed for BMS control through the 0 - 10V
BMS input or through ModBus, the 0 - 10V signal can be
interpreted as either a modulation command or a set point.
When the BMS Type parameter is set to POWER, the 0 - 10V
signal will control the modulation. When set to SETPOINT,
the 0 - 10V signal will control the tank set point. The default
setting is SETPOINT.
Volts at Minimum
When programmed for BMS control through the 0 - 10V
BMS input or through ModBus, the Volts at Minimum
parameter should be set to the minimum voltage signal sent
to the SMART SYSTEM control. The range of this parameter
is 0.0V to the Volts at Maximum value. The default setting
is 2.0V.
Volts at Maximum
When programmed for BMS control through the 0 - 10V
BMS input or through ModBus, the Volts at Maximum
parameter should be set to the maximum voltage signal sent
to the SMART SYSTEM control. The range of this parameter
is the Volts at Minimum value to 10.0V. The default value is
10.0V.
Rate at Minimum Volts
When programmed for BMS control through the 0 - 10V BMS
input or through ModBus and the BMS Type is programmed
as POWER, the modulation percentage represented by the
Volts at Minimum parameter is set by the Rate at Minimum
Volts parameter. When used with a Cascade, this percentage
applies to the total output of the Cascade. The minimum
value is 0% and the maximum is the Rate at Maximum Volts
setting. The default value is 20%.
Service Manual