SETUP & OPERATION
HeatNet Control V3 2.x
SETUP & OPERATION
Basic Multi Boiler System Operation
For boiler system setup/installations please
refer to Refer to the
2008 ASHRAE
Handbook, CH12
or later revision
.
A basic multi boiler system typically uses boilers of the
same size and type. With HeatNet, this includes (1) Master
and (1-15) Member boilers. The boilers are connected
together using an H-Net communications cable effectively
creating (1) boiler. This allows the system heating BTUs to
be evenly distributed amongst all of the boilers. (See: Figure
34, Typical Single Boiler System, page 56).
Figure 2
Basic multiple boiler system
A basic multi boiler system can be configured using the
boiler menus to create custom systems/features. These
features are best described in the section:
Default Settings
& Menu Item Description,
page
Error! Bookmark not
defined.
. Along with these menu items are
hardware support for many auxiliary functions.
Once the system has been properly setup (all default menu
values used and H-Net addresses assigned), the system is
enabled by placing the REMOTE/LOCAL switch to the
LOCAL position on the Master boiler. All Member boilers
must have their respective switches in the REMOTE
position. When the Master boiler‟s Heat Demand input
(LOCAL switch) closes, the system becomes operational
and will fire as many boilers as it needs to maintain the
header water temperature‟s setpoint. See the DHW section
to fire using two setpoints.
When a boiler is to be fired in a multi boiler system (header
water temperature is below the heating band), the Master
checks the HeatNet boilers it has available. Then the Master
checks if a Lead Boiler is to be used (LEAD BOILER > 0).
The Master boiler then looks at which type of firing rotation
it has selected: LOFO, FOFO, TRUE (runtime), or MIXED.
In our example we will use the TRUE (runtime) rotation
since it is the default.
The Master now checks all of the runtimes to determine
which boiler has the least runtime based on the MIN
RUNTIME setting in SETTINGS:FIRING MODE:. The
MIN RUNTIME setting is the minimum runtime interval in
hours that is used to compare boiler to boiler runtimes.
Once the boiler to fire has been determined, the Master
sends the command over the H-Net cable to fire that boiler
and resets the ADD BOILER delay timer to prepare for the
next boiler to fire. If the header water temperature is still
below the heating band and the ADD BOILER delay timer
has expired to zero, the process is repeated until the header
water temperature enters the heating band.
When a boiler receives a command to fire:
NOTE: Runtime messages are displayed in the lower left
corner of the
Home Screen
. See Section
Messages
for
descriptions.
1.
The system pump relay is enabled and the H-Net
control displays “Waiting for Flow” until the flow-
switch closes between J11A, 1 & 2 within the
programmed time (10 seconds default).
2.
All elements in the interlock string, terminated between
J11A and J11B, must be closed before the sequence is
allowed to continue.
3.
If all interlocks are closed, relay K5 is enabled to
command the combustion-air damper open (if used).
The H-Net control displays “Waiting for Damper to
Open” until the damper end switch closes.
4.
Relay K6 is enabled energizing the local pump (if
used). The H-Net control commences its Waiting for
Flow” timer (adjustable 10–240 sec.). The flow switch
contact is checked on terminals J11B, 5 &6.
5.
With all the interlocks closed, the boiler start relay K1
is enabled and energizes terminal 6 on the ignition
control. This signal is present on
J5 Boiler Start
Operator. The control now displays “Waiting for Start
Sequence”
6.
The ignition control begins its cycle and provides an
output signal from terminal 4 to the H-Net control
J5
Blower
. The H-Net control responds and provides an
output signal to the VFD which sets the blower to the
programmed pre-purge speed. If an Ametek blower is
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Summary of Contents for KN-10
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