Laars NTV, Installation And Operation Instructions Manual

Page: 37 / 92

Page 33
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EO
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HERM
Boilers and Water Heaters
Figure 30. Ladder Diagram
Connections for External Control -
Connect the 4-20mA signal from an external control or
building automation system to terminal block 7 (TB7) in
the control panel. The connections are labeled Remote
Analog Input. When making the connections, follow the
polarity designations shown on the label.
Terminal block 8 (TB8) in the control panel can be used
for connecting optional components, such as low water
cutoffs, flow switches, additional high limits and other
field-supplied devices that must be interlocked with
the boiler. These are non-powered dry contacts only.
All safeties or end switches must be wired in series by
removing the supplied jumpers.
7.6 Connections to a
Building Automation System
NeoTherm boilers can be controlled and monitored
through the included Modbus ports. The Modbus wiring
should be completed according to the diagrams shown
below. If alternate communication protocols are desired,
Laars offers “gateways” to allow BACnet, LON, and other
communications protocols. For additional information on
setting up Modbus and other communication protocols,
contact the factory.
Signals from a Building Automation System can be
connected to the MB2 Modbus connections on the
controller. See Figure 28. (MB1 is used to connect to the
Operator Interface (UI).
If multiple boilers are connecting in a cascading Lead/ Lag
arrangement, the signals from the Building Automation
System must be brought in through a System Display.
See Figure 29.
7.7 Ladder and Wire Diagrams
See Figure 30 and Figure 31