Cascade Operation; Cascade Operation Settings - Bosch Buderus SSB399 Control Operations Manual

1 8 | Bosch Buderus SSB255 | SSB399 | SSB512 Boilers

7 Cascade Operation

7.1 Cascade operation settings

Parameter
Permit Emergency Mode
(parameter #72)
Boiler Address
(parameter #73)
Emergency Setpoint
(parameter #74)
Delay Period Start Next Boiler
(parameter #75)
Delay Period Stop Next Boiler
(parameter #76)
Diff erential Down Start Boiler
(parameter #77)
Diff erential Up Stop Boiler
(parameter #78)
"Max. Setpoint Off set Down
(parameter #79)"
Table 13
Data subject to change
Enable Emergency Mode in a multiple boiler cascade installation to ensure that any dependent boiler can operate
independently should communication with the lead boiler be interrupted or the lead boiler loses communication with
the supply sensor. The dependent boiler will operate at a predetermined "emergency" set point which is set using
Parameter #74. Default setting for this parameter is "Disabled".
Boiler Address must be changed when setting up a multiple boiler cascade installation. The default address of every
boiler is set to "0". In a cascade application, the Managing or lead boiler must be set to Address = 1. All other boilers
within the cascade must be set to the next address value. Default setting for Boiler Address is "0". Adjustable from
0 to 16.
"Emergency Setpoint is the fi xed set point which a boiler will operate at within a cascade installation if that boiler has
lost communication with the Managing or lead boiler or the lead boiler loses communication with the supply sensor.
Parameter #72 must be "Enabled" on each dependent boiler and Emergency Set point set for the desired Emergency
temperature at which the boiler is to operate at should the boiler lose communication with the Managing boiler or the
lead boiler loses communication with the supply sensor. Default setting is 113° F. Adjustable from 68 °F to 149 °F.
The amount of time in seconds which must pass once the previous boiler in the cascade rotation is above the power
percentage defi ned in parameter #82 (next boiler start rate) and the system supply sensor is below the target
temperature by the value defi ned in parameter #77 – Diff erential Down Start Boiler. Default value is 15 seconds.
Adjustable from 5 to 300 seconds.
The Amount of time in seconds which must pass once the last boiler turned on in the rotation has dropped below the
power percentage defi ned in parameter #83 (next boiler stop rate). Default value is 15 seconds. Adjustable from 5
to 300 seconds.
In a cascade installation the fi rst or next boiler will be enabled when the system supply sensor is less than the target
system set point minus the value of "Diff erential Down Start Boiler" for a period of time equal to parameter #75
(delay period start next boiler).
If the temperature of the system supply sensor exceeds a temperature greater than System Target Temperature +
Diff erential UP all boilers in the cascade will be stopped.
In order to achieve the desired Target System Supply Temperature during a call for heat the boilers may need to
operate at temperatures greater than or less than the desired Target System Supply Temperature. The operating
range in which the boilers are allowed to adjust the individual boiler supply temperatures is defi ned by the
Off set Down and Off set Up (parameter #80) values. Each dependent boiler will display a "Calculated Setpoint"
temperature on the display which will be within this Off set Range either above or below the overall Target System
Supply Temperature. Default value of Off set UP is 18 F. Adjustable from 0 F to 36 F.
Description
03.2018 | Bosch Thermotechnology Corp.
Control Operations Guide