Slant/Fin VGH-299-CH, Installation And Service Manual

Page: 70 / 128

E93.1601EN032.C VGH installation manual 70
12.6.3 F
LUE TEMPERATURE PROTECTION
The flue temperature protection function protects against the flue gas reaching a too high temperature.
• When the T_Flue or T_Flue_2 sensor measures above the Max_Flue_Gas_Temp, the control generates a
Flue_Gas_Error.
• When the Flue Switch closes, the control generates a Flue_Gas_Error.
When the control is in a Flue_Gas_Error the fan will run at the minimum fan speed.
Boiler power limitation: All boilers have a flue gas sensor. The control will limit the boiler power when the flue gas
temperature reaches the set Max_Flue_Gas_Temp. The maximum boiler power is linearly limited when the flue
gas temperature is within Max_Flue_Gas_Temp
minus 9 ºF (5 ºC) and Max_Flue_Gas_Temp.
Parameters are factory set
12.6.4 A
PPLIANCE SELECTION
The control is designed to store specific parameter sets of different boiler models.
By defining specific setting for different appliance models the same control can be used for a complete product
range. Depending on which model the control is applied to, it only will be necessary to change just one single
parameter.
When this parameter is changed the following settings are changed:
• Maximal fan speed
• Minimal fan speed
• Ignition speed*
• Maximum flue gas temperature
*Ignition speed is the same as Pre-Purge Speed and Post Purge speed.
The following appliances are available:
Appliance type 50 - This is the standard mode used for Natural gas
Appliance type 51 - This is the standard mode used for Propane
Appliance type 52 - 55: Not Used
Ignition cycle
During the ignition cycle multiple safety checks are active
False flame detection If flame is detected at the end of the pre-spark period ( Pre-ignite ) a lockout error occurs
Re-ignition If at the end of the safety period, no flame is detected the control will go to post-purge to
remove the unburned gas. After this a re-ignition attempt is started following the same cycle.
The number of re-ignition attempts is limited to
Max_Ignit_Trials after which a lockout occurs.
Flame establishing time Sparking stops in the Flame Proving state to allow for ionization detection. The
Flame Proving state takes Safety_Period - Ignit_Period .
Flame out too late If at the end of the Post purge 0 state the flame is still detected a lockout follows.
Flame loss When a flame is lost during a burn cycle the control will restart the boiler once. At the second
flame loss the boiler will stop and blocking mode follows. The number of restarts is limited by
the
Max_Flame_Trials setting. (Default set to 1)
Fan supervision
The fan speed is continuously monitored.
Figure 12. 2
Table 12. 8