Description/Operation; Programming Stage Control Values; Control Algorithm; Output Energized - Honeywell T775A User Manual

T775A,B,C,D
INSTALLATION • DESCRIPTION/OPERATION
1. For the T775B and T775D, assign the loads to the
appropriate sensor by setting the DIP switch in the upper
right corner of the T775 (see DIP Switch Selection, Fig. 9).
2. Before programming the T775, verify that the °F/°C
selection jumper is properly installed. The T775 is shipped
from the factory with the jumper installed in the °F position.
If °C is desired, remove the jumper.
3. Apply power to the device. The device will begin
counting down from 210. This countdown sequence will last
for approximately 3-1/2 minutes.
4. Press Select to override this time delay.
5. Press Select and Enter keys simultaneously to begin
programming the load operating mode (Heat or Cool).
6. Press the Set (down arrow) to change to cooling. The
Set (up arrow) will change back to heating.
7. Press Enter to program the displayed mode into
memory.
8. Press Select to go to the next stage.
9. Repeat steps 6 through 9 for additional stages.
10. Press Select after the last stage is set up to return to the
display of the sensed temperature.

PROGRAMMING STAGE CONTROL VALUES

1. Press Select to display the current stage setpoint.
2. Press Set (up arrow) to increase or Set (down arrow) to
decrease to the desired setpoint.
3. Press Enter to enter the displayed value into memory.
4. Press Select to display the current stage switching
differential.
5. Press Set (up arrow) to increase or Set (down arrow) to
decrease to the desired switching differential.
6. Press Enter to enter the displayed value into memory.
7. Repeat steps 1 through 6 to program each additional
stage.
8. For the T775A and T775C, press Select/Select (two
times) to return to stage 1 parameters. For the T775B and

CONTROL ALGORITHM

On/Off Control
The T775A and T775C operate with one temperature
input supplied by the remote sensor while T775B and T775D
have two temperature inputs. The T775A,B,C, and D are all
capable of providing up to four stages of relay outputs for
on/off control. Each stage of the T775A,B,C, and D has its
own independent setpoint that can be configured to operate
in either the heating or cooling mode. The mode of operation
for each stage is user determined by the programming keys.
Heating Mode Operation
• Relay outputs are energized at the temperature set-
point minus the differential value.
• Relay outputs are de-energized at the temperature set-
point value.
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T775D, press Select/Select/Select/Select (four times) to re-
turn to stage 1 parameters. Scroll through the programming
loop a second time to confirm that the appropriate values
were entered into memory by pressing Select.
NOTE: The T775B and T775D have three options for dis-
playing the sensed temperature:
1. Sensor A only.
2. Sensor B only.
3. Alternating between Sensor A and Sensor B.
For the T775B and T775D only:
9. Press Select after viewing the switching differential
for the final stage to display Sensor A temperature only.
10. Press Select again to display Sensor B temperature
only.
11. Press Select again to alternate the display between
Sensor A temperature and Sensor B temperature at approxi-
mately five-second intervals.
12. Before replacing the cover on the T775, check to see
that the control values were recorded on the label on the
backside of the cover.
IMPORTANT: For the T775A and T775C only: After initial
programming, altering the setpoints for stage 1 up or
down will result in a change in setpoints 2, 3, and 4 by
the same number of degrees and in the same direction.
If increasing or decreasing the setpoint for stage 1
results in exceeding the control limits (-40 ° to +220 ° F
[-40 ° to +104 ° C]) for subsequent stages, the control
will not allow the user to enter a value for stage 1
higher or lower than this limit. This will allow for easy
sequential output staging to be modified while keeping
the margin intact between setpoints

Description/Operation

Cooling Mode Operation
• Relay outputs are energized at the temperature set-
point plus differential value.
• Relay outputs are de-energized at the temperature set-
point value.
EXAMPLE: Using a device with one input and one relay
output, the corresponding load would be energized at the
temperatures following based on the initial settings.
Settings
• Setpoint: 68°F
• Differential: 2°F
OUTPUTS ENERGIZED
Heating Mode:
• Stage One: Energized at 66°F.
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