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21.6.10 ALTERNATE LEADER
This parameter allows the Member 1 water heater to automatically assume control of the Cascade should it lose
communication with the Leader water heater. When programmed to YES, it is recommended that the Member 1
water heater have its own set of external sensors installed (such as the Vessel sensor), to maintain the same level of
temperature control as with the Leader water heater. Voltage signals (such as the 0 - 10V system pump speed input)
can be connected to both water heaters.
Do not connect the sensors connected to the leader water heater to the member 1 water heater.
The actual water temperatures will be higher than expected, which could lead to property damage
or personal injury.
When communication is re-established with the Leader water heater, Member 1 will automatically relinquish control of
the Cascade to the Leader water heater.
The default value of this parameter is NO.
21.6.11 WATER HEATER 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 Water heater 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 kBtu/hr):
1.
When the water heater size screen is first accessed, Cascade Address (SELF) is shown.
2.
Press the NAVIGATION dial twice to access the Input setting. Rotate the NAVIGATION dial to
increase the boiler input. Input settings 0 - 400 Btu/hr can be adjusted in increments of 5 (5000 Btu/hr).
When the closest approximate boiler size 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
two above.
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 Optimisation Cascade type when controlling water
heaters of different sizes.
21.7
BUILDING MANAGEMENT SYSTEM (BMS)
21.7.1
BMS
The set point or modulation of the water heater may be controlled through the 0 - 10V BMS input, BACnet, or
ModBus. When the BMS parameter is set to INACTIVE, the 0 - 10V input will be ignored. When set to ACTIVE, the
set point or modulation will be controlled by the voltage on the 0 - 10V input (in the case of 0 - 10V BMS control), or
the 0 - 10V input value received through ModBus or BACnet. The default value is INACTIVE.
21.7.2
BMS TYPE
When programmed for BMS control through the 0 - 10V BMS input or through ModBus/BACnet, 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 SH set
point. The default setting is SETPOINT.
21.7.3
RATE AT MINIMUM VOLTS
When programmed for BMS control through the 0 - 10V BMS input or through ModBus/BACnet 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. The minimum value is 0% and the maximum is the Rate at Maximum Volts
setting. The default value is model dependant.
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