AERCO Modulex E8 Controller (and BCM) For Modulex EXT Boilers - Manual (Page 89)

E8 Controller and BCM for Modulex EXT
Installation, Operation & Maintenance Manual
CHAPTER 8: BOILER COMMUNICATION MODULE (BCM)
OMM-0093_0A AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913 Page 89 of 108
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8.8.3 AERCO BMS II/ACS Modbus Control and Monitoring
The BCM’s modulation output can be controlled by writing to its requested modulation level
register (Standard Holding Register or Control Register #1). It will ramp up the boiler based on
the settings in the Standard Holding Register or Setting Register 3000 to 3015. The default
maximum setpoint temperature limit is 180°F as shown in register 3015. This value should not
be increased, if possible. The default timeout interval is 30 seconds as shown in register 3011.
8.8.4 Modbus Remote Setpoint Control and Monitoring
To send a setpoint temperature to the BCM and have it control the boiler based on its internal
settings, 3 registers need to be adjusted:
• the desired setpoint should be written to the Requested Setpoint (Address 1004) in the
Standard holding Registers or Control Registers. This value should be written at least 3
times within the Communication Timeout time (Address 3011).
• The Heat Request Command (Control Register Address 1021) should be set to 0xEE
(238) to request heat.
• If the modulation level should be allowed to go above 50%, adjust the Maximum
Modulation Level setting (Address 1017).
NOTE
If power is lost, all Control Register settings return to their default
values. Be sure to read them regularly and refresh if necessary.
The changes to the Settings Registers are stored during power-
down.
8.8.5 EMS or BAS Set-Up As Master to BCM Controller Slaves
Refer to the set-up instructions in the manufacturer’s equipment manual for the Energy
Management System (EMS) or Building Automation System (BAS) being used as the controlling
Master.
8.9 Multiple Modulex Boiler Heating Mode – Using A BMS II or ACS
Multiple Modulex boiler plants are the ultimate energy conversion for building space heating. By
modulating input at extremely high combustion efficiency, there is no wasted energy from
overshoot. A multiple Modulex boiler plant offers inherent standby protection and ease of
installation along with longevity.
In a multiple boiler plant of over two boilers, the use of an AERCO Boiler Management System II
(BMS II) Model 5R5-384/AERCO Control System (ACS) is recommended for maximum
efficiency and flexibility of operator control. The BMS II/ACS has the capability of controlling up
to 32 boilers as well as auxiliary equipment. The BMS II/ACS system has an Internal Plant Start
adjustment that can be set from 32°F to 100°F outdoor air temperature. When the boiler plant is
activated, the system pump should be started simultaneously. This can be controlled from
outside the BMS II/ACS, but boilers that fire with no flow will trip out on internal high
temperature limit controls.
The following example briefly explains the operational sequence for a boiler plant consisting of
multiple Modulex Boilers controlled by a BMS II or ACS.
8.9.1 Sequence of Operation (Example: Four-Modulex boiler installation)
When there is a need for heat, the BMS II will send a fire rate signal to the first boiler to begin
firing. The Boiler Communications Module (BCM) of the first boiler will turn on one of its
modules. When the BMS II/ACS fire rate signal to this boiler reaches a value twice that of the