TSBC Instruction Manual Page 7 of 48
Product Features
Boiler Sequence (Continued)
Pre-Sequence States
BOILER
STATE
LCD Display
CONTROL MODE
LCD Display
Description
Boiler
Disabled
Any Mode
(Except for
Remote Control)
Boiler is prevented from starting, Remote On/Off (Enable) (Terminal RO) Input is not
energized.
Warm
Weather
Shutdown
Any Mode
(Except for
Manual Mode)
Boiler is prevented from starting, Warm Weather Shutdown (WWSD) is enabled and
outside air temperature is above the WWSD Setpoint.
Lockout Any Mode
Boiler is prevented from starting, Flame Safeguard lockout is present. A Flame
Safeguard manual reset is required.
Standby
Outlet Sensor &
Local SP Mode
Control monitors boiler outlet temperature, a Call For Heat is initiated when boiler
outlet temperature is below the Operational Setpoint.
Remote Sensor
& Local SP
Mode
Control monitors Remote System Temperature, a Call For Heat is initiated when
Remote System Temperature is below the Operational Setpoint.
Outlet Sensor &
Remote SP
Mode
Control monitors boiler outlet temperature, a Call For Heat is initiated when boiler
outlet temperature is below the Remote Setpoint Input (Terminal C+,C- or Modbus
Interface).
Remote Sensor
& Remote SP
Mode
Control monitors Remote System Temperature, a Call For Heat is initiated when
Remote System Temperature is below the Remote Setpoint Input (terminal C+,C- or
Modbus Interface).
Remote Control
Mode
Control monitors Remote On/Off (Enable) input (Terminal RO or Modbus Interface), a
Call For Heat is initiated when input is energized.
Manual
Operation Mode
A Call For Heat is initiated when Manual Mode Menu item Boiler On/Off is set to On.
Start/Stop Sequence States
BOILER
STATE
LCD Display
CONTROL MODE
LCD Display
Description
Pump Purge
Any Mode
(Except
Manual Mode)
Once a Call For Heat is initiated and Boiler Pump Purge is selected, the pump output
is energized until the Pump Prepurge Time is complete. If the Call For Heat condition
still exists at the end of the Prepurge Time (the temperature of the water at the sensor
may rise with boiler water flowing passed it) the pump will continue to operate and the
Call For Heat Relay is energized.
Limit Hold Any Mode
Power is applied to the safety limit string. If any limits does not pass power (is not
energized), the alarm LED and LCD display shows the reason the start sequence is
on Hold. Refer to Trouble shooting section for explanation of individual lockout and
alarm messages.
Purge / Pilot
Ignition
Any Mode
After the limit string passes power, the fan is started, the modulation output is set to
Purge Rate. When the purge period is complete, the flame safeguard sequences on
the ignition transformer and pilot.
Low Fire /
Ignition
Any Mode
When the Spare Input Low Fire is selected, modulation output is set to the Low Fire
Speed when the Spare Input is energized.
Main Ignition Any Mode
The main gas valve input is energized and the modulation output is held constant for
an ignition stabilization period.
Low Fire
Hold
Any Mode The modulation output is held at the Low Fire for the Low Fire Hold time.
Boiler
Running
Any Mode
When this Low Fire Hold time is complete, the modulation output is released to
modulate.
Fan Post
Purge
Any Mode
When water temperature is above setpoint, there is a Flame Safeguard or Limit fault,
the Call For Heat is ended and the modulating output is set to Purge Rate for the Post
Purge Time.
Pump
Cooldown
Any Mode
When Boiler Pump Purge is selected, the boiler pump remains “on” until the boiler
outlet temperature is less than the Post Purge Delta (default is 5 F) above the Boiler
Inlet Temperature.
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