OPTIONAL FEATURES
HeatNet Control V3
Page 59
Setting up base loading
The base load boiler is controlled using a set of contacts to
enable it (location J4). Enabling/Disabling this relay contact
can be done using any combination of (3) qualifiers to start
the boiler and (4) to stop the boiler. These qualifiers are:
1.
Modulation %
:
a.
START menu item
: The relay contact will close
when the MOD % from the Master boiler exceeds
this value.
SETTINGS: BASE LOADING:
START WHEN: MODULATION IS ABOVE
b.
STOP menu item
: The relay contact will open
when the MOD % from the Master boiler falls below
this value.
SETTINGS: BASE LOADING: STOP
WHEN: MODULATION IS BELOW
If the
START WHEN MODULATION IS
ABOVE
value is set to a value higher than the
SETTINGS: MODULAR BOILER
:
MODULATION MAXIMUM,
all boilers will
be firing before this modulation rate is reached.
This will ensure that all available boilers are
firing before the base load boiler relay is
enabled.
c.
Setting the
STOP WHEN MODULATION IS
BELOW
to a % value slightly above the min fire
rate % of the system will ensure that the base load
boiler will stop before the first condensing boiler
stops. This is due to the Modulation rate being close
to the min modulation rate before the water
temperature exceeds the top of the heating band.
2.
Outside Air Temperature
:
a.
START menu item
: The relay contact will close to
enable the boiler when the OUTSIDE AIR read from
the Outside Air Temperature sensor (if equipped)
falls below this temperature.
SETTINGS: BASE
LOADING: START WHEN OUTSIDE AIR IS
BELOW.
b.
STOP menu item
: The relay contact will open to
disable the boiler when the OUTSIDE AIR read
from the Outside Air Temperature sensor (if
equipped) rises above this value.
SETTINGS:
BASE LOADING: STOP WHEN OUTSIDE AIR
IS ABOVE.
If the OUTSIDE AIR qualifier is used as the
Start and Stop qualifier, ensure that there is at
least a few degrees difference for hysteresis.
3.
Return Water Temperature
a.
START menu item
: The relay contact will close to
enable the boiler when the RETURN IS ABOVE
read from the Return Water Temperature sensor (if
equipped) falls below this temperature.
SETTINGS:
BASE LOADING: START WHEN RETURN IS
ABOVE.
b.
STOP menu item
: The relay contact will open to
disable the boiler when the RETURN IS BELOW
temperature read from the Return Water
Temperature sensor (if equipped) rises above this
temperature.
SETTINGS: BASE LOADING:
STOP WHEN RETURN IS BELOW.
4.
ALWAYS FIRST
:
a.
STOP menu item
: The relay contact will open to
disable the boiler when the temperature exceeds the
heating band. This gives the result of stopping the
Base Load boiler First. Default setting.
Delay time
The DELAY TIME is also included to hold off starting the
boiler until the delay time is met. Once the start condition
qualifier term is met, the DELAY TIME will start counting
down. When the time expires, the base load relay contacts
will close.
SETTINGS: BASE LOADING: DELAY
TIME
. It is adjustable in a range of: 0 to 60 minutes.
Base Load Failsafe
If:
1)
There are no boilers available to fire (offline or
faulted).
2)
There are no boilers in local override.
3)
There is a call for heat.
The J4 Base Load relay will close.
If a boiler becomes available and needs to fire, the Base Load
boiler will remain firing until the temperature exceeds the
band. This is provided to keep the system from entering a no
heat situation.
