Installation & Operation Manual
7 Operating information
The appliance will fire at its ignition speed and will then stage its firing rate to maintain the set point. 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 staging its firing rate to maintain the set point.
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 stage down to its minimum firing rate. Once the demand for that appliance is 0% it will shut down. As the heat demand decreases further, the second to last appliance will stage 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:
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. 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 Space Heating (SH) Night Setback will be done through the Leader boiler. Refer to the
Ramp Delay operation of the boilers as described in the
DAY | SWITCHING ON SEQUENCE |
|
|
Start | |
+ 1 hour | |
|
|
+ 2 hour | |
|
|
54 
