Next Depending To Start Selection; Cascade Error Handling; Cascade Frost Protection - Slant/Fin VHG-100-CH Installation And Service Manual

With parameter First_Depending_To_Start the current depending that is first to start in the sequence is selected.
When the boilers are rotated the parameter First_Depending_To_Start is automatically updated to the next
depending. When boiler rotation is disabled the parameter First_Depending_To_Start is reset to 0.
When the First_Depending_To_Start is manually changed the control will clear all demand of the cascade control.
After this is will start cascade demand generation with the new selection for First_Depending_To_Start.
N
EXT DEPENDING TO START SELECTION
When the cascade Burner_Rotation_Interval has passed the control will perform the cascade rotation. At this
moment the next available control based on the current First_Depending_To_Start is selected.
A depending control is available when the control is present on the communication bus and the control is not
blocked by an error.
When the control is not available the control is skipped as the next First_Depending_To_Start.
Relevant variables
Specific Parameters
Burner_Rotation_Interval
First_Depending_To_Start
Table 14.5

Cascade Error handling

C F
ASCADE ROST PROTECTION
Frost protection on a cascade is active on two levels
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 as follows:
Cascade_Frost_Protection:
Cascade_Frost_Protection
minus 9 °F (minus 5 °C):
Cascade_Frost_Protection
plus 9 °F (plus 5 °C):
Table 14.6
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 14.7
Display menu #
PB 84
PB 175
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/boiler pumps of all the cascaded
boilers will be started and the boilers start burning.
Above this temperature, the boilers stop burning.
Display menu #
PB 155
E93.1901EN032 Installation and Service Manual SlantFin VGH-CH / CO
Level (Default)
Value
Installer 5
Installer 1
Level (Default)
Value
59 ºF
Installer
(15 ºC)
Range
0...30
(0: Disabled)
1...8/16
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)
Range
50...86 ºF
(10...30 ºC)
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