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Flush the system with fresh water
The water of the boiler and heating circuit must be free of any particles, debris and pollution. Therefore, the
complete installation must always be thoroughly flushed with clean water before installing and using the boiler(s).
If a DHW circuit is present, in case of a combi (CO) boiler, the DHW circuit must be cleaned as well.
Automatic air purging
The De-Air sequence is a safety function starting at every power ON and is used to remove the air from the heat-
exchanger. This function must be used after the system has been filled with water during the commissioning
procedure, see paragraph 16.2.
The De-Air sequence does not start after a general reset (e.g. the locking error reset or 24 hours reset).
The display will show 'dAir' indicating that the controller is performing the De-Air sequence to purge the heat
exchanger of air, by sequencing the boiler circulator OFF and ON.
The De-Air sequence can be cancelled by pressing and holding the Enter-button for 5 seconds.
By default, the "De-Air" sequence takes about 14 minutes.
• 1st cycle: The 3-way valve moves to CH position and the general circulator is activated for 10 seconds,
deactivated for 10 seconds, activated again for 10 seconds and then deactivated again for 10 seconds
(DAir_Repeation_OnOff, which means ON/OFF/ON/OFF each time for 10 seconds = 40 seconds in total).
• 2nd cycle: It starts when 1st cycle is ended. The 3-way valve is moved to DHW position and repeats the same
cycle of the circulator (DAir_Repeation_OnOff, which means ON/OFF/ON/OFF each time for 10 seconds = 40
second in total).
This sequence (1st cycles + 2nd cycles) is performed DAir_Number_Cycles times (if DAir_Number_Cycles is 10
'De-air' sequence lasts (10 x 40) x 2 = 800 seconds).
During De-Air sequence no heating or hot water demand will be served. When the water pressure is too low, or
the pressure sensor is in error, the De-Air sequence will be suspended until the water pressure / sensor pressure
is stable again. In that case the De-Air sequence will last longer than the estimated 14 minutes.
If a cascade system has been installed, after commissioning the system the automatic De-air
function must be disabled by means of parameter 139: DAir active.
NOTICE
The following scheme shows the behavior of the 3-way valve and boiler circulator during one complete cycle of
De-Air sequence with a DAir_Repetition_OnOff set to 2.
ON
Boiler Circulator
OFF
Figure 7.15
Relevant variables:
Specific Parameters
De_Air_Config
0= DAir disbled; 1 = DAir enabled
De_Air_State
Current state of DAir function
DAir_Repeation_OnOff
Number of repeating ON/OFF.
DAir_Number_Cycles
Number of DAir cycles.
Table 7.8
Level
Installer
User
Installer
Installer
E93.1901EN032 Installation and Service Manual SlantFin VGH-CH / CO
t
(Default) Value
0
2
10
Range
0...1
0...255
0...255
43
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