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E
XPLANATION OF THE LOW VOLTAGE CONNECTIONS
1-2
If an outdoor temperature sensor is connected, the boiler will control the supply water temperature by using a
calculated setting based on outdoor reset curve, which is related to the outdoor temperature.
3-4
If a low loss header is used, this sensor measures the flow temperature at the system side. The sensor must
be mounted on the supply pipe or in a sensor well at the system side, close to the low loss header.
NOTICE: This sensor (see Figure 7.17 and 7.19) must be used when boilers are cascaded with the internal
cascade manager.
PARAMETER: boiler parameter 122, see paragraph 10.6.
5-6
If combi boiler this connection is connected to the internal sensor on the plate heat exchanger,
for heating only boiler this connection can be used to connect a sensor for an indirect hot water tank.
7-8-9
Connections for a BMS
7 = ground, 8 = A, 9 = B (A detailed manual is available at your supplier on request)
10-11
Cascade connections for the dependent boilers, must be parallel linked together.
NOTICE: link all connections 10 to 10 and all connections 11 to 11, do not mix these.
Link connections 10 of the dependent boilers to 21 of the managing boiler, and connections 11 of the dependent
boilers to 22 of the managing boiler.
12-13
OPTION 1: An ON/OFF thermostat can be connected.
If these terminals are bridged, the set/programmed flow temperature of the boiler will be used.
OPTION 2: An Modulating controller can be connected to these terminals. The boiler software will detect and
use this Modulating signal automatically.
PARAMETER: boiler parameter 124, see paragraph 10.6
14-15
These terminals are used for an external 0-10 VDC control input signal.
NOTICE: Terminal 14 [+] (positive) and terminal 15 [-] (negative).
16-17-18
This connection is internally connected to the flow sensor in a combi boiler and not used on heating only
boilers.
19-20
These connections are used to control the boiler circulator. The PWM signal determines the speed of the
circulator, when there is a heat demand. 18 = Signal (PWM input), 19 = Ground (Signal ref.)
Parameter 136 has to be set to modulating (factory set to on/off circulator) when using a modulating circulator.
21-22
Cascade connection for the managing boiler.
Link connection 21 of the managing boiler to connections 10 of the depending boilers, and connection 22 of the
managing boiler to connections 11 of the depending boilers.
23-24
To be used for an extra external Low Water Cut Off. The boiler goes into a lockout when this contact opens
25-26
To be used for an extra external safety switch. The boiler goes into a lockout when this contact opens
27-28
To be used for an extra external safety switch. The boiler goes into a lockout when this contact opens
Table 10.3
OUTDOOR SENSOR
SYSTEM SENSOR
DHW SENSOR
MODBUS
AL-BUS DEPENDING
ON/OFF STAT OR MODULATING HEATING CIRCUIT
0-10 VDC CONTROL SIGNAL
DHW - FLOW SWITCH
PWM – CIRCULATOR CONTROL
AL-BUS MANAGING / CASCADE
LWCO EXTERN
SAFETY SWITCH 1
SAFETY SWITCH 2
E93.1901EN032 Installation and Service Manual SlantFin VGH-CH / CO
VGH-CO
BOILERS
79
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