Sigma Holzgas, Manual And Installation

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Boiler overheating temperature [A 99] - value, exceeding which causes 
permanent turn off of the fan to prevent boiler overheating. After the 
temperature increases above 80

˚

C the central heating pump is turned on to cool 

down the boiler. Overheating mode is shown by indicating error [E  2] on the 
display. It can be turned off by pressing STOP button, but only when 
temperature decreases below this temperature. 
Fan turn off also occurs in case of damage of the boiler temperature sensor 
which is shown on the display with error [E  1]. 

STB

 - the controller has additional protection against overheating which is 

independent from the processor. In case the temperature increases over 95°C, 
the control process is turned off by turning the fan off and launching the central 
heating pump. The fan and the pump are turned on to the control process again 
when temperature drops below 89°C.  
STB circuit enables more precise boiler work control and reduces overheating 
possibility. 
 

(6) No 

fuel 

No-fuel testing time during fuel firing start [Fd60] - after switching to WORK 
mode, if water temperature does not increase by 5°C in programmed time, the 
control process will be turned off and the display will show the message: 
[FUEL]. 
You can return to previous mode by pressing STOP button. No fuel testing time 
during fuel firing is finished after the set temperature is achieved. 
No-fuel testing time during work mode [Fb30] - in WORK mode, if temperature 
of water in the boiler decreases below temperature set with the thermostat, by 
hysteresis value, and does not increase by 5°C in the programmed time, the 
control process  will be turned off and the display will show the message: 
[FUEL]. 
You can cancel the alarm by pressing STOP button. 
 

(7) Additional 

output 

Additional output [Ar 0] – the controller has been equipped with an output that 
allows connection of the UM module. When the Ar parameter has the UM 
module value “0” it may control the oil or gas boiler – if such boiler exists in the 
heating circuit. After switching the controller with the main power switch the 
additional boiler is turned off and it turns on again when there is no fuel in the 
solid fuel boiler. This function is useful in heating systems where there is a solid 
fuel boiler used to cut the heating costs. After erasing the “no fuel” alarm by 
pressing STOP button the additional boiler is again turned off and the controller 
works again. Setting parameter [Ar] to “1” allows controlling the additional alarm 
signaling system with the UM module – which occurs on the controller. 
When Ar parameter is set to “2” the UM module allows controlling the mixing 
valve servo-motor in the central heating circuit depending on the room 
thermostat input. In this case the work of central heating pump depends only on 
the boiler temperature.