OPTIONAL FEATURES
HeatNet Control V3 3.x
Page 75
The next screen will display the files on the USB thumb drive.
Select the settings file for the boiler.
The file will be hi-lighted to confirm the selection and
displayed in the File Name display box. Select “OK”.
The file will be displayed in the File Name display box. Select
the Restore button
The saved settings will be loaded, the control will reboot, and
the boiler will run with the new settings.
Diagnostics
The H-Net control can display and identify faults in a
meaningful way. If an interlock trips, it will be indicated in
the main screen display, along with an audible alarm
(mounted on control board) and a set of relay contacts will
close. A record of this, with a time stamp, will also be entered
into the log as an aide in the diagnosis of the event. The log
can be downloaded, and a histogram used to display the data.
If using MODBUS, BACnet, or LonWorks, there are software
flag bits in registers available.
Open and shorted sensors are checked continuously, so that in
the event of a sensor failure, the system shuts down and the
alarm relay is closed. If the sensor returns to operation the
alarms are automatically cleared and operation is restored.
If a pump fails (flow switch required), or the flow switch
fails, the boiler will cycle the start condition every 10 minutes
in an attempt get the boiler restarted.
If the damper fails to open and never closes its proof switch, a
retry algorithm will attempt a retry. Every 10 minutes the
damper relay will cycle and try to open the damper again.
If the H-Net control closes the last interlock string connected
to the ignition control and the ignition control never closes its
Blower Relay, the H-Net control will wait 2 minutes. The H-
Net control will then retry for the duration of the local pump
post purge time and then retry the ignition sequence. During
this time “retry strt” will be displayed in the status screen.
After (5) attempts the H-Net control will lock out and display
call service.
Blower Protection
With the use of the Ametek blower the HeatNet control has
assumed many of the responsibilities that the Variable
Frequency Drive provided. Some of these include
Acceleration, Deceleration, Braking, and Soft Start.
The most sensitive of these (4) functions is the Soft Start. The
Soft Start overcomes the motor’s attempt to run at a high rate
of speed before overcoming inertia. In the larger Ametek
blowers a higher starting torque is required to break the inertia
of the Ametek’s flywheel effect. If the Ametek motor cannot
transform its electrical energy into mechanical energy fast
enough, (due to this inertia) a high input current to the motor
will result. The Ametek motor would then shut down and lock
out due to this current. The only way to reset the Ametek
blower due to the over current condition is to remove power
from the boiler for several minutes.
Also, due to the nature of the inverter circuit that is used to
change the AC line input to a DC voltage to power the motor,
a sizable bank of capacitors is used. When the blower is first
powered up, these capacitors are empty and develop a large
inrush of current.