Product Features
Boiler Control Instruction & Operation Manual
Page
9
of68
Boiler Protection Features
Limit Devices
The control monitors individual limit devices as shown in Figure 6 below. If any of these limits open the
boiler will shut down and an open limit indication is provided. Additionally, the control monitors an air
proving switch.
STAT
S6: Domestic Hot Water Demand
OFF
Note
During the boiler start sequence the
control requires the Air Proving Switch,
“API” to be “OFF” before the blower
starts and in the
“ON” position after the
blower starts. If the API is not in the
required position the start sequence is
halted or the boiler is shut down and
the
“Low Air Pressure” OFF limit
indication is provided.
Figure 6: Limit Monitoring Screen Showing Central Heat Demand
Table 5: Limit String
Limit
String
Type
Description
Action
STAT
Heat Demand
After a Heat demand is received,
“ON” the control is enabled to fire to
maintain water temperature at setpoint.
Heat demand may be received from
“STAT” terminal for Central Heat
demand,
“S6” terminal for Domestic Hot Water demand, the Sequence
Master, or EMS Modbus Inputs.
A Heat Demand input ON initiates pumps and Fresh Air Damper outputs.
LCI
Load Control
Input
The boiler will not start if the LCI is OFF, when it is turned OFF during run the
boiler shuts down.
Hold message is shown when LCI limit is OFF and Heat Demand ON.
LCI Hold will never cause a manual reset lockout.
Boiler may be disabled remotely by wiring an enable contact to the LCI
“External Limit” terminals.
When the Low Air Pressure Switch (APS) is proven OFF the LCI input
turns ON and initiates blower start. When Low APS fails to turn ON, the
control enters a manual reset Lockout state.
ILK
Interlock
The boiler will not start if the ILK is OFF. When it is turned OFF during run the
boiler enters a manual reset Lockout state.
The ILK must be ON within 1 minute after the LCI is ON. This time allows
the blower to start and the air flow proving switch to turn ON. Failure to
close will cause a manual reset lockout
ILK OFF Lockout cause the Lockout Alarm contact to turn ON.
