Install Instructions

42
5 Electrical connections
TABLE 5B
Maximum Setpoint Determination
OJ1 OJ2
Max.
Setpoint
Connected Connected 230°
Cut Connected 190°
Connected Cut 200°
Cut Cut 160°
NOTICE
Anytime that OJ1 is the only jumper cut, a
new overlay is required under the Set Point
knob on the temperature controller because
the scale has changed to a maximum of
190°F.
Anytime the OJ2 jumper is cut (with or
without OJ1), a new overlay is required
under the Set Point knob on the temperature
controller because the scale has changed to
a maximum of 200°F.
Setpoint
The Set Point knob specifies the target water temperature in
degrees, Fahrenheit. After the water temperature reaches the set
point, the temperature control shuts off the burners.
Differential
The Differential specifies the number of degrees below the set
point that the control will allow the water temperature to drop
before it brings the unit back on again.
Installation & Service Manual
High-fire offset
The temperature control operates a two-stage firing system.
The two stages are High-Fire and Low-Fire. High-Fire operates
all burners while Low-Fire operates approximately one-half of
the burners.
The High-Fire knob specifies the number of degrees below set
point that the High-Fire stage shuts down. At that point, the
unit will continue to operate at the Low-Fire stage until the set
point is reached.
The High-Fire offset knob has settings between 0°F and 20°F.
If set at 0°F, the High-Fire offset is disabled and the unit will
operate at the High-Fire stage until the set point is reached and
the temperature control shuts the unit off.
When the High-Fire offset knob is set to 0 or 1, the unit will
light at Low Fire and operate for approximately 10 seconds
before the High-Fire stage actuates. When set to 2 or above, the
unit will operate at Low Fire for approximately 2 minutes before
the High Fire stage can actuate.
Figure 5-11_Optional outdoor reset control
OUTDOOR
AIR
SHUTDOWN
SHUTDOWN
OUTDOOR
AIR
SENSOR
RATIOOUTDOOR
AIR
MAX
Outdoor reset option
For boilers ordered with the Outdoor Air Reset option, there
is an additional control (see FIG. 5-11). There are three setting
knobs for Shutdown, Outdoor Air Max., and Ratio. There is
also a switch to turn the outdoor air sensor On or Off. An O.A.
Sensor is also included.
Shutdown
The Shutdown knob specifies the outdoor air shutdown
temperature at which the control would prevent the unit from
operating. This feature can be enabled/disabled with the O.A.
Shutdown switch.
Outdoor air max (O. A. Max)
The O. A. Max knob allows a reset up to the maximum outdoor
air temperature specified by this knob setting. When the
outdoor air temperature is above the specified setting, the unit
will not function in the O.A. Reset Mode, but will continue to
run at the selected set point temperature.
Note that the set point knob will now indicate the “minimum”
boiler temperature. Target temperature is determined by the
ratio and outdoor air temperature below the O.A. Max setting.