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The appliance will fire at its ignition speed and will then
modulate its firing rate to maintain the set point (M9 and B9
only). If the first appliance reaches 100% of its firing rate, the
Leader will calculate at what point the second appliance could
fire at its minimum firing rate. At this point, the Leader will fire
the second appliance on the Cascade. For a new startup, this
would be the first Member appliance. The appliance will fire at
its ignition speed and will then modulate its firing rate to
maintain the set point (M9 and B9 only).
If the set point still cannot be met, the Leader will continue
firing more Members until either the heat demand is met or all
appliances on the Cascade are firing. As the heat demand
decreases, the last appliance on will modulate down to its
minimum firing rate (M9 and B9 only). Once the demand for
that appliance is 0% it will shut down. As the heat demand
decreases further, the second to last appliance will modulate
down and shut off. This will continue until the demand is
satisfied and all appliances are shut off.
Sequence of the cascade
To equalize the run time of all appliances on the Cascade, the
firing sequence will automatically be changed at set intervals.
For the first 24 hours after initializing the Cascade, the sequence
will be changed every hour. After that the sequence will be
changed once every 24 hours. The switching on/off sequence
will be as follows:
DAY SWITCHING ON SEQUENCE
Day 1 L-M1-M2-M3-M4-M5-M6-M7
Day 1 + 1 hour M1-M2-M3-M4-M5-M6-M7-L
Day 1 + 2 hour M2-M3-M4-M5-M6-M7-L-M1
DHW, Night Setback, and Ramp Delay operation with
cascade
For indirect DHW operation any boiler(s) in the Cascade can be
selected to provide heat for a DHW call. Select a boiler to be
designated as the DHW boiler. Connect the tank thermostat or
tank sensor to the corresponding terminals on the low voltage
connection board. When the boiler receives a DHW call, the
Leader control will take that boiler out of the Cascade sequence.
If another boiler is available, the Leader will start it up to take its
place.
The DHW boiler will adjust its set point to the programmed
outlet set point and will adjust its firing rate to maintain this
(M9 and B9 only). Once the DHW call has been satisfied, the
Leader control will place that boiler back into the Cascade
sequence.
Switching of the boiler between DHW operation and SH
operation when there is a call for both does not occur. The boiler
will provide heat for the DHW demand until it is satisfied.
Night Setback operation of the boilers or water heaters within
the Cascade is available. Programming of the Night Setback will
be done through the Leader boiler. Refer to the Power-fin
Service Manual for information regarding Night Setback.
Ramp Delay operation of the boilers as described in the
Power-fin Service Manual is not active when the boilers are part
of a Cascade system.
8 Operating information
Installation & Operation Manual