TSBC Instruction Manual
Page 15 of 48
Product Features
Auxiliary Device Control
M
M
System Pump
Feedback
(
SI
)
Spare Output
(
VI
)
Standby System Pump
Start
/
Stop
(
SO
)
System Pump
Start
/
Stop
(
SP
)
Boiler Pump
Start
/
Stop
(
BP
)
Mixing Valve
Control
(
MR
,
MS
)
System
Supply Water
Return
Water
Combustion Air
Damper
Open
/
Close
(
SO
)
Boiler Outlet
Temperature
(
BO
,
BC
)
Boiler Inlet
Temperature
(
BI
,
BC
)
Energy Management
System
(
EMS
)
Interface
Fresh Air
Supply
Modbus RS
-
485
,
RJ
-
11
Connection
POWER
Auxiliary Control Application Diagram
(Showing All Options)
Features
Mixing Valve
The primary function of the mixing valve is to protect the
boiler from thermal shock and sustained flue gas
condensation. When configured, the mixing valve output
compares both minimum return water temperature setpoint
to measured return water temperature and boiler
differential temperature setpoint to measured differential
temperature (boiler outlet minus inlet temperature).
If the boiler return water temperature drops below the
minimum inlet water temperature setpoint (“Min In H2O
Temp” parameter) or the differential temperature increases
above the maximum water differential temperature setpoint
(“Max H2O Delta T” parameter) the mixing valve opens to
allow hot boiler outlet water to blend with cold return water.
The valve repositions toward 0% recirculation after return
water increases above setpoint and the differential
temperature reduces below setpoint.
The mixing valve may be controlled manually from the
Manual Mode menu when Supervisor password is entered.
Simply set the Mixing Valve M/A parameter to “Man” and
adjust the Mixing Valve % as required. Once activated the
green LED flashes. To leave manual mode set the Mixing
Valve M/A parameter to “Auto”.
Combustion Air Damper and Vent Inducer
When the Relay (CH) is closed, the Combustion Air
Damper (CAD) and Vent Inducer outputs are energized. If
the CAD open position is needed to be proven, a limit
switch may be wired in series with the Low Water Cut-off
Switch input (LC). The alarm Message may be modified to
reflect this change.
Boiler Pump
The Boiler Pump output (BP) may be configured as None,
Always On, Purge or Lead On by setting the Boiler Pump
(parameter 2) (refer to page 28):
Always On
Boiler pump runs continuously.
Purge
Boiler pump runs during a pump Prepurge
[Pump Prepurge (parameter 3) time before
boiler starts], while the boiler is running and
during a pump cooldown period. [Pump
cooldown maintains the boiler pump running
until the boiler outlet temperature is within
the Postpurge Delta (parameter 4) degrees
above the boiler inlet temperature.]
Lead On:
Boiler Pump runs continuously when the
boiler is the lead and during the fan pre-
purge, while the boiler is running and during
fan post purge when a lag boiler.
The boiler pump sequences are detailed on the boiler
sequence diagram on page 6.
System and Standby System Pump
When configured, the System Pump output (SP) is always
energized except when turned off by the Warm Weather
Shutdown feature. A Standby System Pump output (SO)
may be configured as a backup to the system pump. The
Standby System Pump is started based on the System
Pump Feedback input (SI).
Selecting This Control Mode
These control modes may be selected using the Boiler and
System Configuration menus.
