Cascade Error Handling; Cascade Frost Protection; Emergency Mode; Loss Of Cascade Communication - Slant/Fin VGH-299-CH Installation And Service Manual

Cascade Error handling

15.4.1 C F
ASCADE ROST PROTECTION
Frost protection on a cascade is active on two levels
1. Frost protection for burner cascade
The 'frost protection' function for a burner cascade is related to the boiler sensor temperatures.
Reactions on the supply / return temperatures of the managing boiler are
Cascade_Frost_Protection:
Cascade_Frost_Protection
minus 9 °F (minus 5 °C):
Cascade_Frost_Protection
plus 9 °F (plus 5 °C):
Table 15-6
2. Frost protection on boiler
As last protection the controllers for the boilers can force themselves to burn.
If the boiler supply/return temperature drops below 41 °F (5 °C) the boiler starts at minimum power and continues
burning until the lowest of both supply and return temperatures are above 59 °F (15 °C).
Specific Parameters

Cascade frost protection

Temperature for frost protection
Table 15-7
15.4.2 E
MERGENCY MODE
Managing boiler error
When the managing boiler is in error mode, the depending boilers can go into the "Emergency_Mode", if enabled.
In emergency mode the system setpoint is set to the temperature of the Emergency_Setpoint and all cascaded
boilers start burning on this setpoint.
NOTE: the default setting is 158 °F (70 °C)! Make sure the right temperature is set.
Specific Parameters
Permit Emergency Mode
Emergency Setpoint
Dair active
Table 15-8
For proper functioning of this emergency mode, the following settings are necessary in the managing boiler
(installer password required):
- Module Cascade parameter no. 72: "Permit_Emergency_Mode" has to be set on "yes".
- Module Cascade parameter no. 75: "Emergency_Setpoint" has to be set on the right temperature.
- Boiler parameter no. 139: "Dair active" has to be set on "No".
NOTE: do not de-activate the Dair function before commissioning the system and adjusting the boilers!
When the managing unit is reset from lockout state, the cascade controllers are re-initialized.
15.4.3 L
OSS OF CASCADE COMMUNICATION
The burner controller of the managing boiler is aware of how many dependents should be present in the system.
The total number of boilers is stored in the
has to detect all depending boilers within 60 seconds.
When not all dependent boilers are detected the control will show the CC_Loss_Communication warning. When
the communication with any of the depending boilers is lost during operation, the control will show the
CC_Loss_Communication warning after 60 seconds, which is purely informative and will not block the control.
Below this temperature the cascade CH/system pump and
the general pump of the managing boiler start running.
Below this temperature the cascade heat demand is
activated; the general pumps of all the cascaded boilers will
be started and the boilers start burning.
Above this temperature, the boilers stop burning.
Level (Default) Value
2: Installer 59 ºF
(15 ºC)
Level (Default) Value
Installer Yes
Installer 158 ºF (70 ºC)
Installer Yes
BCU (parameter 147). When powering on the system the leading boiler
E93.1601EN032.C VGH installation manual
as follows:
Range
50...86 ºF
(10...30 ºC)
Range Parameter
Yes/No Module Cascade parameter 72
68 - 194 °F (20 - 90 °C) Module Cascade parameter 75
Yes/No Boiler parameter 139
Default: 59 °F
(15 °C)
59 minus 9 = 50 °F
(15 minus 5 = 10 °C)
59 plus 9 = 68 °F
(15 plus 5 = 20 °C)
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