Honeywell R7426A Product Data

R7426A,B,C TEMPERATURE CONTROLLER
7 63-2564—1
On the R7426C controller each output characteristic can be
selected via parameters DIR/REVx (where x is O1, O2 or O3).
Fig. 8 shows:
• Dir characteristic for all outputs.
• Control of damper signal within the range Xp2.
NOTE: If no cooling actuator is available, the parameter Xpc
can be set to Off.
If parameter Xpc is Off, the cooling signal is set to 0 percent
and damper output is maintained at 100 percent above control
point (CTRP2).
Fig. 8. Cascade control output sequence.
Economizer Modes
Economizer modes are suitable for installations where the
main temperature sensor (I01) is installed in either return air
or the room with a constant offset between room and return air
conditions. The offset value is programmable within 0°F to
10°F with parameter RetOffs which will be added to the actual
room temperature value to simulate return air conditions.
NOTE: Economizer mode is disabled if parameter RetOffs is
programmed Off, or no OAT sensor is connected.
By comparing the conditions of outside air with return air, the
O1 output on the three-output controller operates using Mixed
Air Dampers or an Energy Recovery System.
Economizer Mixed Air Damper Mode
Economizer mixed air damper mode is active when:
• RetOffs is not Off.
• O1CTRF is 0.
NOTE: See Table 3 for control logic and Fig. 9. for sequence
output operation.
Table 3. Economizer Mixed Air Damper Mode.
NOTE: A fixed hysteresis of 2°F is used to switch between
MINPOS and actual O1 control output signal.
Fig. 9. Mixed air damper sequence output.
Economizer Energy Recovery System
Economizer energy recovery mode is active when:
• RetOffs is not Off.
• O1CTRF is 1.
NOTE: See Table 4 for control logic and Fig. 10 for
sequence output operation.
Table 4. Economizer Energy Recovery System Mode.
NOTE: A fixed hysteresis of 2°F is used to switch between
100 percent and actual O1 control output signal.
Fig. 10. Energy recovery sequence output.
Outside Air Temperature O1
Greater than return air
temperature
MINPOS
Less than return air
temperature
Included in sequence control
Outside Air Temperature O1
Greater than return air
temperature
100 percent
Less than return air
temperature
Energy Recovery System
included in sequence control.
MINPOS is not active.

Honeywell R7426A Specifications

General

Brand	Honeywell
Model	R7426A
Category	Controller
Language	English