Honeywell T775 Series 2000 Application Manual page 19

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.
STAGES
STAGE 3 ON
STAGE 2 ON
STAGE 1 ON
STAGE 1
-33%
1 206°F
THROTTLING RANGE (18°F)
STAGE ENERGIZES
DISCHARGE WATER TEMPERATURE
1
Fig. 20. Boiler control staging behavior (when effective
setpoint = 200° F).
°F
220
SP MAX A1
210
(BOILER MAX)
S
200
E
N
190
S
O
180
R
A
170
SP MIN A2
160
(BOILER MIN)
150
140
10
RESET B1
(OUTSD MIN)
Fig. 21. Reset curve with optional setback offset.
HYST.
STAGE 3
STAGE 2
0% 33% 67%
200°F 194°F 188°F
STAGE DE-ENERGIZES
M28043
SETBACK
OFFSET
-10°F
(OPTIONAL)
20 70
30 40 50 60 80
RESET B2
(OUTSD MAX)
SENSOR B
M24869
T775 SERIES 2000 ELECTRONIC STAND-ALONE CONTROLLERS
Wiring
All output relays should have a common power wiring source,
which may or may not be the same as the T775 power wiring.
See Fig. 22.
NOTE: The Multi-Stage Boiler Control (Reset) application
continues on the next page.
Multi-Stage Boiler Control (Reset)
(continued)
SENSOR B (OUTSIDE AIR)
SENSOR C
(RETURN WATER)
L1
(HOT)
PUMP
L2
BOILER #1
L1
(HOT)
L2
BOILER #2
BOILER #3
°F
1 POWER WITH 24 VAC OR 120/240 VAC AT THE APPROPRIATE TERMINAL BLOCK.
24 VAC POWER TERMINAL BLOCK.
2
Fig. 22. T775P wiring — multi-stage boiler control
19
SENSOR A
(DISCHARGE WATER)
T
T
T
T775P
T
T
T
2
+
C
RELAY RELAY
4 3
NC
NC
C
C
NO NO
NO
NO
C C
NC NC
RELAY RELAY
1 2
with reset.
1
120 VAC
M24868
63-7147—05