OPTIONAL FEATURES
HeatNet Control REV 1.38-1
Page 27
The following are types of Failsafe
conditions.
1.
Building Management System Failure
If a BMS system is controlling the setpoint and enabling
the boiler system, a timer is provided to allow operation
of the system in the event that communications are lost
with the BMS system. The HeatNet boiler system will
run locally if communications is lost and this timer
expires due to the lack of being updated.
The system setpoint timer and system setpoint work in
tandem to externally control (i.e. a BMS - building
management system) the operating setpoint. The setpoint
(countdown) timer should be loaded with a timeout value
(in seconds) prior to writing the system setpoint. When
the timer reaches zero, the control assumes that the BMS
is no longer operating and the local setpoint (saved on the
control) is reloaded. If the setpoint timer is not written, a
default timeout value of 60 seconds is assumed. The
timer is automatically reloaded with the default value
when a setpoint is written.
The BMS mode is always on and no menu
item is available.
2.
Heat HeatNet Communications Lost
SETUP:AUX FUNCTIONS:FAILSAFE MODES:
H-NET COMM LOST
:
This mode allows a member boiler to run in LOCAL if
the communications link via the H-NET cable is lost.
This includes the MASTER boiler losing its Control
board, Communications board, or the power on the
MASTER is switched OFF. When this MODE is set to
ON, and if the member boiler loses it’s link (heartbeat
packet over the H-NET cable) to the MASTER Boiler,
this MEMBER will fire to the LOCAL setpoint.
The heartbeat packet over the H-NET cable
needs to be lost for 10 minutes
This MEMBER boiler will continue to run at the LOCAL
setpoint until H-NET communications from the MASTER
boiler is re-established.
Ensure that this Member boiler’s Damper and System
pump control are configured correctly with the assumption
that the Master is not powered. Also ensure that any other
System settings related to outside air temperature sensing
and system interlocks are set to provide safe operation.
3.
Low Temperature Protection
LOW TEMP:OFF, SUPPLY, HEADER,
DHW, or RETURN
This mode may be used by the MASTER or MEMBER
boiler, and can be used as a type of freeze protection. In
this mode you may select which Sensor you wish to
monitor, or you may opt to turn this mode OFF. If you
select a sensor, you may then associate it with a
temperature at which the boiler will turn ON. Once the
temperature at this sensor falls below the LOW TEMP
temperature the boiler will start and fire to its LOCAL
setpoint. Once the Boiler reaches it’s setpoint it will turn
OFF.
4.
Using the base load relay.
If there are no boilers available to fire (offline or faulted)
and there are no boilers in local override, and 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.
Additional Features
1. Support for Domestic Hot Water using a temperature
sensor or a dry contact from a tank thermostat. Also, a
separate relay contact for a DHW pump or Valve is
provided.
2. On-Board HeatNet and Modbus connections. A second
terminal connector for daisy chaining the H-Net
connections when using shielded wire.
3. Low fire hold switch for ease in calibrating.
4. A ‘U’ shaped socket system for mounting the
Protocessor module. No other wiring connectors are
required when connecting BACnet & LonWorks, other
than the BACnet or LonWorks network cable.
5. Option input for special features. Support for Dual Fuel
using a switch located on J12B terminals 5 & 6.
