T775 SERIES 2000 ELECTRONIC STAND-ALONE CONTROLLERS
63-7147—3 22
— STG8/Pump: (Relay 8 controls the pump output)
1
Enable = YES
Exercise = YES or NO
Prepurge = -300 to 300 seconds (default is 0)
Postpurge = 0 to 300 seconds (default is 0)
Stages 1-4: Control to the discharge water temperature
Program for: (Refer to the reset curve in Fig. 26.)
— Boiler Max = 210° F (99° C)
— Outside Min = 20° F (-7° C)
— Boiler Min = 160° F (71° C)
— Outside Max = 70° F (21° C)
— Throttling Range= 20° F (-7° C)
—Sensor A
—Heat
1
See Notes in “Programming Example” on page 18 for an
explanation of Prepurge and Postpurge times.
IMPORTANT
After the desired value is selected, be sure to press
the # or $ or HOME button in order to save that
value in the controller’s memory.
IMPORTANT
By programming the boiler setpoint at 210° F
(-99° C) the T775 has established 210° F (-99° C) as
the highest operating point that will be allowed when
the temperature falls below 20° F (-7° C). As
temperature increases above 20° F (-7° C), the boiler
will be reset downward per the reset ratio until it
reaches the minimum setpoint of 160° F (-99° C), at
70° F (21° C) and above outdoor temperature.
Fig. 25. Staging Behavior (when the effective setpoint =
200° F (93° C))
Fig. 26. Reset Curve.
NOTE: The 4 Stage with Pump Output and Reset application
continues on the next page.
M28010
STAGE 2 ON
STAGE 3 ON
STAGE 1 ON
-25%
STAGES
HYST.
75%0% 25%
STAGE 4 ON
50%
STAGE 1
STAGE 2
STAGE 3
1
1
DISCHARGE WATER TEMPERATURE
STAGE 4
205°F 185°F200°F 195°F 190°F
STAGE ENERGIZES STAGE DE-ENERGIZES
THROTTLING RANGE (20°F)
SENSOR B
SP MAX A1
(BOILER MAX)
SP MIN A2
(BOILER MIN)
200
140
10
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
M24878
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