OPTIONAL FEATURES
HeatNet Control V3
Page 65
Once a file has been selected, a STORAGE LOCATION
needs to be selected. There are (2) storage locations for the
new file. Location 1 is used for normal updates and Location
0 is for the factory stored backup file. When the Storage
location (default is Location 1) is selected the file will be
loaded into a permanent storage memory location. Next, the
control will reboot and copy this new program into running
memory, reboot, load factory defaults, and then reboot again.
Selecting
USB CABLE
requires
connecting a USB cable and
running the Firmware Update program from a PC directly to
the USB port on the control board (not the front Panel). This
process takes much longer and requires a Personal Computer
(laptop) to be taken to the boiler site. Again, follow the on
screen prompts to down load the program into a storage
location as done when using the above USB DRIVE loading
menu. You will need the HeatNet Pro software which can be
downloaded from the website.
Selecting
SAVE FILE
will display the currently stored files
in the storage memory locations. Use the arrow keys to select
a stored file for copying to running memory. When
SELECT
is pressed the file will be marked so it will be loaded on the
next power cycle. Power cycle the boiler to begin copying the
file from stored memory to running memory.
NOTE:
to access the factory backup program, the P3 BOOT
shunt on the HeatNet control board needs to be connected and
the CAL/NORMAL switch placed in the CAL position. The
BOOT jumper is located close to where the ribbon cable for
the display plugs in. If the control is power cycled in this
condition, the factory program will overwrite the existing
running program. If in the LOAD FIRMWARE menus,
STORAGE LOCATION 0 will be an allowed storage
location.
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 power
cycle the boiler.
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.
In order to provide a means of controlling these situations and
preventing downtime, the HeatNet control allows a relay to
control the power fed to the blower. This is done by wiring
the 120 VAC power to the J13A.1 Stage 4 relay contact using
black 600 V, 18 gauge, MTR/TEW wire. Then wiring (same
wire type) from J13A.2 to the Ametek blower contactor’s
enable input. This allows the HeatNet control firmware to
control power to the blower by switching the contactor ON or
OFF. The reasons for this are as follows:
1.
The Stage 4 relay has been allocated to help bring the
power up in steps. These steps are used to minimize
inrush currents by engaging the blower’s contactor (7)
seconds after the main power has been applied.
2.
In the event a blower lockout has been determined, a
(10) minute retry cycle, (3) times will occur. At the time
the blower has been detected as locked out, the retry
cycle will start. The Stage 4 relay will be de-energized
for (8) minutes. Then the Stage 4 relay will be energized
for (2) minutes. This will effectively power cycle just
the blower. The call for heat will then be allowed in an
attempt to start the boiler. After (3) failed retry attempts,
the boiler will lock out.
