Honeywell T775U - Manual (Page 28)

T775U SERIES 2000 ELECTRONIC STAND-ALONE CONTROLLER
62-0255—07 28
3. PROGRAMMING OUTPUTS
(MOD AND RELAY) WITH
RESET
The T775U can be programmed for Reset or No Reset for
each output. From the factory, the T775U is programmed
for No Reset. This section describes the steps necessary
to program the controller for Reset.
To use the Reset feature, the first output (MOD 1) must be
set to Reset=YES in Setup mode (see “3.1. Setting Up the
Controller for Reset”).
NOTE: Even if the MOD outputs are not used, both
MOD 1 and MOD 2 must be set to Reset in order
to configure Reset for the relay(s).
The reset curve established when programming the first
output (MOD 1) is then used for all subsequent outputs
that are configured for Reset, and each of those outputs
will be offset from this curve.
For all outputs that will follow a reset curve, be sure to
configure for Reset=YES in the setup mode. Choose
Reset YES or NO for all other outputs you wish to reset,
then press the HOME button to record your selection.
Fig. 64. Reset Setup.
NOTE: The first output, Mod 1, must be set for Reset to
enable the controller’s Reset function.
3.1. Setting Up the Controller for Reset
1. Press and hold the MENU button for five seconds to
enter Setup mode.
2. Then choose:
OUTPUTS X
MOD1 X
RESET X
then select YES-BOILER or YES-OTHER (Fig. 64).
You can now press the HOME button to exit Setup mode
and continue with “Determining and Setting the Reset
Values”.
Determining and Setting the Reset
Values
NOTE: When using the Reset feature, Sensor A must
be sensing the controlled temperature (e.g.
Boiler), Sensor B must be sensing the resetting
temperature (e.g. outdoor temp).
To program an output for Reset, refer to the values as
shown in the examples below. Choose your own
appropriate values for Sensor A maximum and minimum
and Sensor B maximum and minimum.
Reset Example:
(see Fig. 65)
• Sensor A is the boiler sensor and Sensor B is the
outdoor sensor.
• Maximum boiler temperature desired is 210°F when
the outdoor temperature is 20°F.
• Minimum boiler temperature desired is 160°F when the
outdoor temperature is 70°F.
• With the above settings example, when the outdoor
temperature is 50°F, the effective setpoint is 180°F.
Setback (optional) Example: (see Fig. 65)
• Setback of -10°F is used to drop the temperature at
night by 10°F.
• With the above settings example, when the outdoor
temperature is 50°F, the effective setback setpoint is
170°F (180°F setpoint minus the 10°F setback).
NOTE: A single reset curve is programmed for the
MOD 1 output and is used by all outputs setup
with RESET=YES.
CAUTION
If using the time clock or DI to go to setback,
the T775P will shift the reset curve up or down
and cause the controlled setpoint to exceed
either the entered reset max. temp or min.
temp (dropping below reset minimum is most
common, since setback is normally below
setpoint). If this is not desired, either do not
use setback, or adjust the min. and max.
values entered so that critical setpoints are
not exceeded in the setback mode.
When Reset is programmed, the home screen displays
the calculated Heat/Cool setpoint(s) for the Mod and
Relay outputs based on the reset curve. See Fig. 21 on
page 12.
SETUP
OUTPUTS
MOD 1
RESET
SETUP
OUTPUTS
MOD 1
RESET
USE RESET
FOR
MOD 1
YES-BOILER
YES-OTHER
NO
M24568