Submittal Sheet

3. PROGRAMMING OUTPUT (LOOPS AND ADDITIONAL RELAYS) WITH RESET T775L SERIES 2000 CTLR
25 62-0257–05
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 (loop or relay) for Reset, refer to the
values as shown in the examples below and in Fig. 59.
Choose your own appropriate values for Sensor A
maximum and minimum and Sensor B maximum and
minimum.
Reset Example: (see Fig. 59)
• 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. 59)
• 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 first
output and is used by all outputs and loops setup
with RESET=YES.
NOTE: For subsequent outputs (Loop 2 and Relay), a
setpoint offset is used if that output is also being
Reset. See “3.4.1. SETPOINT OFFSET (Loop 2
only)” on page 28.
NOTE: When setback is used, the minimum and
maximum boiler temperature setpoints that were
entered will also be offset by the setback offset.
This may not be desired if it is necessary to
maintain the minimum temperature (to avoid
condensing) or maximum temperature entered in
the reset schedule. In this case, we recommend
adjusting the minimum and/or maximum
temperature by the offset so that during setback
the desired limits are maintained.
When Reset is programmed, the home screen (Fig. 15 on
page 9) displays the calculated Heat/Cool setpoint(s) for
the Loop and Relay outputs based on the reset curve.
Fig. 59. Reset Curve for Loop 1 with Setback Offset.
The remainder of this section beginning with “3.2.
Entering Program Mode” describes the individual
parameters for configuring outputs with Reset.
For your reference, the following Reset programming
procedure uses the values in Fig. 59.
SENSOR B
SP MAX A1
(BOILER MAX)
SP MIN A2
(BOILER MIN)
200
140
10
SETBACK
OFFSET
-10°F
190
20
30 40 50 60
70
°F80
150
160
170
210
220
180
°F
RESET
B1
(OUTSD MIN)
RESET
B2
(OUTSD MAX)
S
E
N
S
O
R
A
M24404