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on outdoor temperature. Operation as a reset controller
is based on temperature input from two sensors, one
immersion sensor for boiler water and one for outdoor
air reset. Each sensor is a positive coefficient platinum
thermistor. Sensor A is the boiler water temperature
sensor and sensor B is outdoor air temperature sensor.
A liquid crystal display is provided to indicate sensed
temperature and operating parameters. The temperature
control with the outdoor reset function operates with
two (2) stages of control.
Outdoor Reset Electronic
Temperature Control Display
And Programming Keys
SPECIFICATIONS
Set Point Adjustment Range: Max setting 220 ° F.
Temperature Accuracy: +/- 1 ° F.
Display Resolution: 1 o F via Liquid Crystal Display
Sensor: Thermistor 4.8 ohms/ ° F.
Operating Humidity: 5 - 95% RH Noncondensing.
Operating Ambient Temperature: -30 ° to 140° F.
Access to the control is achieved by removing the jacket
panel covering the diagnostic control lights. Four
programming keys are provided to program set point
and differential values for each stage and to control
the display. The four keys are Select, Up arrow, Down
arrow and Enter.
Select Key - Sequentially prompts the user as to what
parameter is being displayed: set point, differential,
stage energized, operation mode (heat), indication of
assigned stage (1,2). Once the last parameter value has
been viewed, pressing the Select key will display the
control values again from the beginning of the display
loop.
Up and Down Arrow Keys - Allow the displayed
parameter to be increased or decreased. After pressing
the Select key, a control value can be changed by using
the Arrow keys. Control values will be increased or
decreased by 1 ° F for each time the Arrow keys are
depressed.
Enter Key - Places the new value into the memory of
the microprocessor.
IMPORTANT:
A control value or operation will not be entered in
the memory of the microprocessor until the Enter
key is pressed.
Control values and operation selection will remain in
the device memory even after power is removed.
Select and Enter Keys simultaneously pressed -
Changes operation mode of the control from heat to
cool mode. DO NOT CHANGE THIS SETTING.
This control must always be in the "heat" position for
proper operation of the boiler.
When all stages have been programmed the display will
revert back to sensed temperature and load energized
status.
FIG. 33
Once power is applied to the temperature controller
the display will countdown from 210 until the display
reads zero. All outputs are de-energized at this time.
This countdown process will repeat each time main
power is interrupted. To avoid viewing this entire
countdown, press the Select key. The display will now
show normal readings: load (sensed) temperature,
stages energized, and which sensor is being read
(Sensor A or Sensor B). At any time during the
programming procedure, the display will revert back
to showing the sensed temperature and stage status
indication 60 seconds after the last programming key
is pushed.
The display can be configured with three options to
show sensed temperature. The display can lock on
Sensor A temperature, lock on Sensor B temperature,
or be configured to alternatively indicate "Sensor A"
and "Sensor B" sensed temperature at a 5 second rate.
This allows comparison of boiler water temperature
and outdoor temperature to check reset operation.
29
DISPLAY
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