KEY RK-2001W2N, Operation Manual, Page: 9 / 16

9
STB - the controller has additional protection from 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.
5.6. No fuel.
No-fuel testing time during fuel firing start [Fd2h] - after switching to WORK mode,
if water temperature does not increase by 2°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 [Fb2h] - 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 2°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.
5.7. Additional output.
Additional output work mode [Ar 0] - the controller is equipped with a multipurpose
output that can work in one of following modes:
- [Ar 0] mode - output may control oil or gas boiler if such boiler exists in the
heating circuit. After switching the controller on with the main power switch, the
additional boiler is turned off and it turnes on again when there is no fuel in the solid
fuel boiler. This function is useful in heating systems where the solid fuel boiler is used
to cut heating costs. After erasing no fuel alarm by pressing STOP button, the
additional boiler is again turned off and the controller works again.
- [Ar 1] mode - output may control additional alarm signaling system. Boiler
temperature sensor malfunction, overheating or no fuel alarm will turn on the
additional alarm.
- [Ar 2] mode - output may control mixing valve servo-motor. Controlling the
mixing valve requires room thermostat to be connected to the controller. The mixing
valve is being opened and closed depending on the room thermostat input.
Additionally, mixing valve is opened in case of overheating or boiler temperature
sensor malfunction.
- [Ar 3] mode - output may control boiler emergency cooling system (e.g. pump).
In this mode the additional output is turned on in case of boiler overheating or boiler
temperature sensor error alarm.