Heating Method 4 Aa Input - RBI FUTERA XLF Series Control Manual
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CONTROL METHODS
Closing the other contact will fire the boiler at MAXIMUM
output (the same rate as closing the AA input).
Figure 19
Stage control inputs
The maximum output of the boiler is based on
the MAX VFD setting in the calibration mode
and not the nameplate rating.
The AA, HEAT DEMAND (LOCAL) input, the H-Net, the
4-20mA input will all override the stage control inputs.
Heating Method 3
4-20mA Control
Placing a current source between the + and – 4-20mA inputs
will allow remote control of the boilers setpoint. An
adjustable starting mA current signal here will start and then
fire the boiler. See: ADVANCED SETUP: 4-20mA
INPUT: CHANNEL MODE.
See section OPTIONAL FEATURES, Using the 4-20mA
input for extensive detail.
A 4-20mA signal will fire the boiler to the setpoint based on
the set parameters. . The input current signal is tabled with
the default parameters 4mA signal = 50 degrees F and
20mA signal = 200 degrees F. These (2) temperatures are
adjustable to provide a custom setpoint range. The
minimum start current is also adjustable between 3.71 and
5mAThe boiler start signal is 4.10mA. This will act as a
start/stop for the boiler if a jumper is placed on the 4-20mA
enable as an alternative to using a relay for enabling and
disabling.
The AA terminal, the HEAT DEMAND, and the H-Net
NETWORK are the only inputs that will override the 4-
20mA input.
Page 24
Method 2
Stage Control Inputs:
T1 & T2
Heating Method 4
AA Input
HIGH FIRE input Control: The AA input will fire the boiler
at HIGH fire (maximum output of the boiler). No other
inputs can override this input. AA / High fire input.
Figure 20
Example: 4–20 mA connections
Heating Method 5
MODBUS communications
The fifth method uses an RS485 digital communications
cable with the MODBUS protocol to control the boiler
using the H-Net network. The Boiler or Boiler network will
run as in Method 1, but instead of the HEAT DEMAND
input, a software form of the HEAT DEMAND input is
used (40001: Boiler/System Enable/Disable). See:
MODBUS COMMUNICATIONS section.
Figure 21
MODBUS connections
HeatNet Control V3
Modbus Using
RJ45 Cat 5 cable
Building
Management
Modbus Using
shielded 3 wire.
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