OPTIONAL FEATURES
HeatNet Control V3
Page 62
In low volume systems sudden temperature changes may
occur when the flow is stepped up or down by a large
percentage. In these situations the SETTINGS: ADAPTIVE
MODULATION: MODULATION MODE may need to be
changed from ADAPTIVE and the ORIGINAL KN method
used. Other adjustments may also be required.
Currently, no failsafe mode is available in the event the
Master boiler’s control fails. If this method is employed, a
failsafe boiler could be used to override the control signal and
enable the system pump’s VFD using some external wiring
and an external relay, or have the VFD default to a safe speed
on loss of the control signal.
If (2) pumps are available, pump rotation is available. The
rotation of the (2) pumps can be controlled using two
methods.
3.
Pumps are switched based on the system run time
4.
Pumps are switched by the difference between each
pump’s runtime. The HeatNet control keeps a
running record of each pump’s runtime in hours. If
a pump is taken offline or replaced. The runtimes
can then be adjusted until they become equal.
These features may be selected in the menu, SETTINGS:
SYSTEM PUMP: PUMP ROTATION
The
local circulator pump
is supported by (3) modes and (2)
features.
1.
The first mode allows the circulator pump to remain on,
unless the control’s outside high air temperature setting
has been met when using Warm Weather Shutdown.
2.
The second mode will allow the circulator pump to be
turned on whenever there is a call for heat (any control
input). This mode will stop the circulator pump when the
call for heat is lost and the pump post purge time has
been satisfied.
3.
The third mode works much the same as mode 2, but it
allows the inlet sensor (RETURN) to be used with the
outlet sensor (SUPPLY) to keep the pump on until a delta
(difference) temperature is met. A return temperature
sensor is required for this mode, because the delta
temperature (SUPPLY – RETURN) measured is across
the boiler. In this mode, the post purge time is also used.
After the delta temp has been met, the post purge time
needs to expire before the pump is turned off. This mode
works much the same as mode 2.
Local Pump Options
MASTER PUMP/VALVE REMAINS ON
: This is a special
feature of the local circulator pump to prevent deadheading
water flow when all boilers are off. When this feature is
enabled, the Master boiler will enable its local circulator
pump/valve when
NO
boilers are running. If boilers are
running in LOCAL override and not controlled by H-NET,
but are visible to H-NET, the pump(s) on these boilers are
presumed ON. In this situation, the Master
will not
enable its
circulator pump/valve unless it is running.
Local & DHW Pump connections
Local Pump/Valve
Normally Closed &
Normally Open Contacts
DHW
Normally Closed &
Normally Open Contacts
Another feature of the PUMP/VALVE OPTION is to control
a local (primary) pump using a Variable Frequency Drive.
This feature may be required when a secondary system pump
is also variable speed. To enable this feature
SETTINGS:
LOCAL PUMP: LOCAL PUMP VFD: ON
. Setting this
Option to ON will map the control signal on J4 pins 1+ and 5-
to the modulation rate. (2) Wires need to be run from J4.1+
and J4.5- to the VFD’s input connection. Ensure that the JS1
shunt jumper on the control board is in position 0-10 or 4-20
mA as required.
