ECKELMANN WRG 3010 E, Инструкция по эксплуатации, Страница: 24 / 113

Firmware V1.4 20.05.2021 24/113
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5.2 Low Temperature Heat Recovery LT
The functional unit heat recovery LT consists of a heat exchanger, a hot gas valve, a water pump and the
associated temperature sensors. There must always be 2 temperature sensors for hot gas (inlet, outlet) and 2
temperature sensors for water (inlet, outlet).
When a higher-level BMS requests it via digital input 1 (terminals 50/51) and after a switch-on delay of 150
seconds has elapsed, the calculation of the internal power signal starts. An exception to this is the button "LT
Off" , which is located on the "WRG 3010 E" visualisation. If this has been tapped, the internal power
calculation is also suppressed. There are two ways to calculate the internal power signal; for details, see Power
Signal .
If the internal, calculated power signal reaches the "Desuperheat ON" threshold, see " Visualisation in LDSWin -
HT / LT / Power Signal Setpoints , the water pump starts. The speed control is activated immediately and is
based on the spread between the water outlet temperature and the water inlet temperature of the heat
exchanger:
If the spread is below the setpoint, the pump turns slower.
If the spread exceeds the setpoint, the pump turns faster.
Furthermore, a minimum speed and a maximum speed can also be set for the pump.
If there is a collective fault message from the pumps at digital input 5 (terminals 58/59: Message appears when
the digital input is de-energised), this is forwarded as an alarm to the system centre. In this case, the pump is
not switched off, as electronic pumps would otherwise not be able to be switched on again without further
action.
As soon as the pump is running (and there is no fault from it), the hot gas valve is activated. This directs the hot
gas into the heat exchanger, where it releases its energy to the water. The valve reports both end positions
back to the controller, where "closed" stands for bypassing the heat exchanger and "open" for introducing the
hot gas into the heat exchanger. The feedback of the valve must also always match its control. If this is not the
case, an alarm is sent to the system centre. Due to the run times of the installed valve actuators, there is a
waiting time of 260 seconds when switching over, during which no alarms are issued.
The following monitoring devices are available and lead to a forced closure of the hot gas valve, the pump
continues to run:
A flow monitor in the water circuit, which is read via digital input 18 (terminals 84/85: "Good" state when
voltage is applied) . If the flow monitor trips for at least 1 minute , the hot gas valve is forcibly closed and an
alarm is issued.
An optional pressure transmitter, which is read in via analogue input 4 (terminals 45/46), is compared with a
limit value. If the measured pressure falls below the limit value continuously for an adjustable time, it must
be assumed that there is no longer sufficient water in the system. Then the hot gas valve is forcibly closed
and an alarm is issued. This option must be selected and its set values must be configured; for details
see
Figure "Setpoints HT LT power signal" .
The flow and return temperatures are monitored and if an adjustable limit value is exceeded, the hot gas
valve is forcibly closed and a prio 0 message is issued. The hot gas valve is not enabled again until the
value falls below the triggering limit value by 3 Kelvin.
The low-temperature heat recovery LT is an option and does not have to be present in all systems. The
prerequisite for this operating mode is that this function has been selected in the visualisation; for
details
see figure "HT, LT Power Signal Setpoints" .
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A digital request and an analogue power signal are always required for operation!
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