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Bradford White
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Copper Brute II
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The heater target temperature is set using the
BOIL TARGET item in the Adjust menu.
Note: External demand is not required in this
mode of operation.
Tank Differential – A differential setting that
operates above and below the TANK TARGET is
selectable using the TANK DIFF item in the Adjust
menu.
6.3.9 Outdoor Reset Operation
When either mode 4 or 5 is selected, the control
uses outdoor reset to control the water temperature.
Outdoor reset adjusts the target temperature based
on the outdoor air temperature and reset ratio. The
reset ratio is determined from the Boiler Start, Boiler
Design, Outdoor Start and Outdoor Design settings.
Heat Demand – For “heat demand” to exist,
there must be continuity between the Com D (common
demand) and the Ht D (heat demand) terminals. The
heater ships with a jumper between these terminals.
The control also evaluates the sensor(s) installed
in the system. If the control is not in warm weather
shutdown (WWSD), and the sensor(s) are below the
target temperature, the Dem segment is turned on
in the display. The control energizes the pump (on
pump mounted boilers) and energizes the Pmp-Pmp
terminals, and the heater pump segment is turned on
in the display. The control then operates the stages to
maintain the set point temperature.
Boiler Start (BOIL START) – The BOIL
START temperature is the theoretical boiler supply
water temperature that the heating system requires
when the outdoor air temperature equals the OUTDR
START temperature setting. The BOIL START is
typically set to the desired building temperature (see
Figure 15).
Outdoor Start (OUTDR START) – The
OUTDR START temperature is the outdoor air
temperature at which the control provides the BOIL
START water temperature to the system. The OUTDR
START is typically set to the desired building
temperature.
Outdoor Design (OUTDR DSGN) – The
OUTDR DSGN is the outdoor air temperature that is
the typical coldest temperature of the year where the
building is located. This temperature is used when
doing heat loss calculations for the building.
Boiler Design (BOIL DSGN) – The BOIL
DSGN temperature is the water temperature required
to heat the boiler zones when the outdoor air is as cold
as the OUTDR DSGN temperature.
Warm Weather Shut Down (WWSD) – When
the outdoor air temperature rises above the WWSD
setting, the control turns on the WWSD segment
in the display. When the control is in WWSD, the
Dem segment is displayed if there is a heat demand.
However, the control does not operate the heating
system to satisfy this demand. The control does
respond to a set point demand and operates as
described in the Reset Override section (next).
Reset Override (SET POINT DEMAND)
– This is used when override of the outdoor reset curve
is needed, such as when an indirect water heater is
served by the heating system. A set point demand is
required whenever heat is required for the set point
load. The set point demand overrides the reset water
temperature. The control turns on the Setp Dem
pointer in the display. The control energizes the pump
(on pump-mounted heaters), energizes the Pmp-Pmp
terminals, and turns on the heater pump segment in the
display. The control then operates the heater stages to
maintain the programmed target temperature. The reset
override operation is not affected by WWSD.
6.3.10 External Heater Operation
When mode 6 is selected, the control allows for
an external control to operate the heater’s stages. In
this mode, the control operates the pump in order to
provide purging and exercising. The staging operation
is provided by an external device such as an Energy
Management System (EMS) or External Staging
Control.
Heat Demand – A heat demand is generated
when stage one is wired properly, and the external
control closes the contacts on the stage one terminals
(1C-1NO), calling the heater for heat. The heater is
shipped with a jumper between the Com D and Ht D
terminals, and this jumper must remain in place when
and external control is providing the heat demand
Figure 15. Temperature Control Outdoor Start Graph.