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7.D.2 TB2 (for pumps and aux power)
7.D.2.a Boiler Pump
This terminal and the 120V(N) terminal will provide power to the boiler pump whenever the boiler is running. Use this to
power the Low Loss Header (LLH) pump. If not using a LLH then this terminal can run power for a single zone or a zone
valve system pump.
7.D.2.b SYS Pump
This terminal and the 120V(N) terminal will provide power to zone
pumps or a zone valve system pump. This terminal cannot be used
if the boiler does not have a dedicated boiler pump that is connected
to the boiler pump terminal. When a system pump and dedicated
boiler pump are piped and wired correctly, the control will energize
the boiler pump only. Once the control detects high enough supply
water temperature, the system pump will be enegized. This feature
helps protect the boiler from condensation due to low inlet water
temperature.
7.D.2.c Aux Power
This terminal and the 120V(N) terminal provide constant high voltage to accessories such as power vent, combustion air
and/or zone relay systems. Only the field supplied service switches or the main circuit breaker will interrupt the power to
these terminals.
7.D.3 TB3 (for optional equipment)
7.D.3.a DHW Pump
These two terminals along with the GND terminal provide 120V
during a DHW call. They are powered continually as long as
DHW Aquastat terminals are closed.
7.D.3.b DHW Aquastat
These are 24VAC terminals that energize a relay when they
are closed. The relay powers the DHW pump terminals and
communicates with the boiler control to switch from heating
settings to set point targeting.
M
INI-
T
HERM
JX
Residential Boilers
®