Electric Boiler Controller NELBC-1
B
ASIC
P
RINCIPLES
OF
B
OILER
O
PERATION
The electric boiler controlled by NELBC-1 may work both in both continuous and timer mode
where the heating works only within time intervals defined by week programmer setup. Regardless
of the heating timers set, domestic hot water heating, when enabled, always starts when flow rate
sensor registers use of hot water. On standby state, the boiler does not work neither for heating nor
domestic hot water heating, except for when frost protection function is activated, if enabled.
In order to avoid overloading the electrical installation, the heating and domestic hot water heaters
are not allowed to work at the same time, and when it is necessary to turn on the domestic hot water
heater, the other heater is temporarily switched off.
The output of the heating elements is controlled precisely in order to maintain required temperature.
As the heater for heating installation is turned on, the circulation pump is also automatically turned
on, and when the heating is stopped, the pump continues to work for another 5 minutes. When
heating is started the output power is increased smoothly, which extends the life of the boiler and its
adjacent components.
5 seconds after the pump is turned on, the controller starts to monitor whether the fluid in the
system is flowing. If the flow switch (flow rate sensor) does not detect fluid movement in the
heating circuit, then the heater and pump are shut down and a "No Flow" error is activated. After 2
minutes an new attempt is made to turn on the heating again. If this time the sensor detects fluid
flow then the error is cleared, otherwise the heater and the pump are switched off again. The
controller continues heating re-start attempts each 2 minutes.
While the pump is working the pressure is also monitored. If measured pressure is higher than the
set maximum value, only an error is activated. However, if pressure is below the minimum value, in
addition to the error activation, the heater and the pump are turned off and the boiler is switched to
Standby.
The boiler is switched to Standby whenever one of the following emergency situations:
•
fault of any of the temperature sensors (disconnected or short-circuit)
•
negative temperature at the outlet of heating element for heating or DHW
•
overloading on any of the phases of heating element for heating or DHW
•
low pressure in heating system
To start the DHW heater, the flow rate sensor should measure more than 1 L/min. If the flow rate
falls below 0.5 L/min then heater is turned off. Accordingly when flow rate sensor is used in heating
system, fluid flow is registered above 1 L/min and if the flow rate falls below 0.5 L/min the
controller considers that there is no flow. The maximum flow rate value that the controller shows is
25.5 L/min. If flow rate is higher then the value will be 25.5 L/min again.
User Manual / revision 1.2
стр. 7 от 36
