AM Series Boiler & Water Heater User Manual
CHAPTER 5: INSTALLATION
– ELECTRICAL
OMM-0100_E
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GF-146
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11/15/2019
Technical Support
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(800) 526-0288
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Mon-Fri, 8 am - 5 pm EST Page 59 of 170
Figure 5-4: 0-10 VDC Analog Input Algorithm
5.1.4 MODBUS Interface Connections
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Boilers and Water Heaters
The AM Series models 500, 750 and 1000 are factory supplied with a Communications Module
(the 399 model can be equipped with one as an option). This MODBUS interface can be
connected to drive the unit from a building management device. Refer to the AM Series
MODBUS User Manual (GF-146-MB), which is available from AERCO technical support and the
AERCO website (
5.1.5 Connection to a LWCO Device
Use only LWCO sensor device. To use water flow switch, ask the manufacturer for an
engineering wiring diagram.
Install LWCO device as per engineering method. Connect LWCO to heater terminals terminals
103 and 104.
WARNING!
Heater terminals 103 and 104 containing line voltage; an electrical shock hazard will exist.
5.1.6 Alarm contact
Alarm contact works only in presence of the 885 IF board (see Figures 2-9, 2-12 and 2-15, item
13).
Alarm contact does not react in case a dependent module (burner 2, 3 or 4) is in error.
