FEATURES & SPECIFICATIONS
HeatNet Control REV 1.38-1
Page 5
the exact status of each Member boiler. When a new boiler
is added, the Master boiler adjusts the system modulation
rate lower to compensate for the BTUs that will be
introduced by the newly added boiler. This adjustment
occurs when the newly added Member boiler enters its ON
CALL state (default setting). This can be changed to PILOT
when the new boiler is called using the menu:
ADVANCED
SETUP:ADAPTIVE MOD:DROP DOWN.
Once the
Main Valve (on the newly added boiler) is opened, and the
DELAY RELEASE
timer equals zero, the PID algorithm is
allowed to control the system modulation. Setting the
DELAY RELEASE timer will allow some “soak” time of
the newly added boiler before releasing modulation control
to the PID.
The ADAPTIVE MOD menus are disabled on a
Member boiler, but are still visible.
Member
If a “SYS/DHW HEADER” sensor is
not
connected to J10, a
boiler always defaults to the role of Member.
The Member boiler can operate as part of a multi-boiler
system or as a stand-alone unit.
In a multi-boiler system the Member typically receives its
command signals from a designated Master-boiler. It is also
capable of receiving inputs from an external control system.
The boiler responds to these signals, to start/stop the burner,
and/or to modulate the firing rate. The outlet water
temperature is also monitored. If the outlet temperature
approaches the operating limit temperature setpoint
(adjustable), the boilers firing rate is limited and its
modulation value is reduced to minimize short-cycling. If the
operating limit is exceeded, or if an interlock trips, the boiler
is shut down. When connected with a network cable, in a
Master/Member role, the Members' status is interrogated by
the Master boiler.
In a stand-alone installation the Member typically receives its
command signals internally and operates based upon the outlet
water temperature input and the established settings in the
menu (Local Set-point) to start/stop the burner, and/or to
modulate the firing rate. If the operating limit is exceeded, or
if an interlock trips, the boiler is shut down. As in a multi-
boiler system, a stand-alone Member boiler is also capable of
receiving inputs from an external control system.
When using the H-Net network cable in a Master/Member
system, the system setpoint is sent from the Master as a digital
signal, along with the modulation value to control firing rate.
It also receives its command to start or stop over the H-Net
cable. Also, the SYSTEM CLOCK only needs to be set on the
MASTER. The Master will then set the time on all member
boilers.
If not using the H-Net protocol (cable), an external control can
send a 4-20ma signal along with a 4-20ma enable signal to
control the firing rate or setpoint. The boiler may also be
treated as a 2-stage boiler or an ON-OFF boiler using the
dedicated T-inputs.