Heating Control Methods; Heating Method 1; Heating Method 2; Heating Method 3 - RBI FUTERA XLF Series Control Manual
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Also See for FUTERA XLF Series:
- Installation and operation instructions manual (44 pages) ,
- Manual (40 pages) ,
- Installation and operation instructions manual (44 pages)
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CONTROL METHODS
Heating Control Methods
An overview of the (5) methods for controlling the Futera
III/Fusion series boiler are presented here. They are outlined
in more detail at the end of this section.
Heating Method 1
The first method is to use the Futera III/Fusion Series boiler
in its standalone modulating method. This method uses a
PID algorithm to maintain a setpoint and is enabled using
the HEAT DEMAND input. Closing a relay contact or
switch across the HEAT DEMAND input will cause the
Master boiler to control all Member boilers using H-Net.
Any standalone boiler will perform better
when controlling to a header sensor.
A Fusion, as a standalone boiler, requires a
header sensor to control properly.
A Member boiler may also be controlled by the HEAT
DEMAND input (LOCAL mode). The Member boiler will
then ignore commands from the Master and maintain its
LOCAL SETPOINT at the supply sensor.
Heating Method 2
The second method is to view the Futera III/Fusion boiler as
two separate boilers or as a HIGH/LOW boiler using T1 &
T2.
Heating Method 3
The third method is to allow a remote 4-20mA or 0-10VDC
signal to control the setpoint of the boiler using the 4-20mA
input, along with the 4-20mA REMOTE ENABLE input.
Heating Method 4
The fourth method turns the boiler ON and OFF @ 100%
modulation using the AA terminal.
Heating Method 5
The fifth method uses an RS485 digital communications
cable with the MODBUS protocol. The boiler is controlled
by writing and reading registers using MODBUS
commands. A bridge module may also be used to convert
BACnet or LonWorks protocols to MODBUS.
Page 22
Short cycling may occur when a firing rate is
sent to a Member boiler that would cause the
supply temperature to rise high enough to trip
the operating limit (low flow rate). After the
supply temperature falls, the boiler would
restart and the process may continue. A
Member boiler would use its supply (outlet)
sensor to protect itself from short cycling by
limiting the firing rate coming from the
Master. This occurs in the event that the
Member's supply temperature increases
above the (OPERATE LIMIT- OPERATE
LIMIT BAND).
Operating Limit
When the Master boiler or an external control input is used
to control a Member boiler (i.e. AA, T1-T2, 4-20mA, H-
Net), a software operating limit on the Member boiler will
be used to limit the maximum output of the Member boiler.
This operating limit can be adjusted in the SETUP:
SETPOINTS: OPERATING LIMIT.
There is also an associated operating limit band that must be
set in conjunction with the operating limit to help prevent
this LIMIT from being reached. Its purpose, is to limit the
output of the boiler as it approaches the operating limit. If
the band is set to 10 degrees, then for every degree that it
approaches the operating limit, the maximum output will be
lessened by 10%. With a band of 20 degrees, for every
degree that it approaches the band, the maximum output will
be lessened by 5%. You can think of this operating limit as
a smart aquastat which prevents the High Limit from
tripping. This method minimizes boiler short cycling when
using external inputs. The minimum setting is 1 degree and
effectively turns the limit band OFF. The default setting is
20F.
Input Priorities
The Futera III/Fusion-Series control inputs are prioritized
so that multiple levels of external control can be employed
at the same time. This means that if we are firing the boiler
with a low Priority input and a higher Priority input is called
for, the boiler will now fire at the higher Priority input.
When the high Priority input is removed, the boiler will
revert back to the lower Priority input that is still being
called.
Priority 1
The AA terminal has absolute control, and if used, will
always fire the boiler at 100% output, regardless of any
other input.
Priority 2
The HEAT DEMAND input is the next, and provides the
means to operate the boiler in LOCAL MODE when an
HeatNet Control V3
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