Settings And Adjustments - Honeywell C7046C Product Data

SOLID STATE ECONOMIZER SYSTEM
M7415 Damper Actuator
Single M7415 Damper Actuator accepts thermistor sensor
input from a C7046A or a C7150B Mixed Air Sensor mounted
in discharge or mixed air duct. See Fig. 13.
During the occupied period, on a call for cooling, when
outdoor air temperature or enthalpy conditions are low, the
M7415 Actuator proportions to maintain between 50°F (10°C)
and 56°F (13°C) at the thermistor sensor.
If the mixed or discharge temperature is above 56°F (13°C),
the M7415 Actuator opens to admit additional outdoor air until
the temperature returns to the 50°F (10°C) to 56°F (13°C)
range. If the mixed or discharge air temperature is below
50°F (10°C), the actuator proportions closed, shutting the
outdoor air damper until the temperature returns to the 50°F
(10°C) to 56°F (13°C) range. During the occupied period, the
actuator does not close past the minimum position.
If the fully open M7415 Actuator cannot satisfy the space
demand, mechanical cooling is sequenced on.
During the unoccupied period, the M7415 Actuator overrides
the minimum position setting and drives fully closed. On a
loss of power, the actuator spring-returns fully closed.
The M7415 Actuator can also accept the Q769A 6- to 9-volt
Adapter. The Q769A is factory calibrated so that the motor
drives open from the closed position at 6.2 Vdc. A nominal
M7415 Actuator drives closed from the open position at 8.8 Vdc.
If terminals P and P1 are jumpered, the M7415 drives fully
open; however, if terminals P and P1 are left open, the
M7415 drives fully closed. The M7415 minimum position
adjustment drives the motor open when the resistance across
P and P1 is minimal. Increasing the amount of resistance
across these terminals drives the actuator closed.
M8405 Damper Actuator
An spst low voltage controller is used to control the M8405
Actuator as follows:
a. Fully open—when the controller circuit closes to
provide 24 Vac to terminals D and T, the actuator
is energized and runs fully open.
b. Fully closed—when the controller circuit opens,
power is removed from terminals D and T, and the
actuator spring returns to the fully closed position.
c. Mid-position—when the controller circuit closes to
provide 24 Vac to terminals T and X, the actuator
is energized to run to the adjustable mid-position
(minimum position).
Adjustable minimum position can be reached from either the
fully closed or fully open position. From fully closed, the
actuator drives open to the minimum position; from fully open,
the actuator spring-returns to minimum position.
W7459A,C,D Solid State Economizer Logic Module
The purpose of an economizer is to use outdoor air for
cooling, whenever possible, to reduce air conditioner
compressor operation. The W7459 Economizer System,
when wired as shown in Fig. 10 or 13, responds to a signal
from the cooling thermostat. This system uses a C7400 Solid
State Enthalpy Sensor or a C7650A Solid State Temperature
63-2484—1
Sensor. It responds to both dry bulb temperature and
humidity, allowing the use of outdoor air at higher
temperatures for free cooling when the humidity is low.
The economizer functions as a true first stage of cooling and
provides maximum fuel economy during the cooling cycle.
The economizer is automatically locked out during heating. It
holds the outdoor air damper at the minimum position setting.
On a call for cooling by the space thermostat, the system
operates as follows:
When the enthalpy or temperature of the outdoor air is below
the setpoint, the outdoor air damper is proportioned open
(and the return air damper is proportioned closed) to maintain
between 50°F and 56°F (10°C and 13°C) at the mixed/
discharge air sensor. During economizer operation, the
mechanical cooling is operated by stage 2 cooling on the
space thermostat.
When the enthalpy or temperature of the outdoor air is above
the setpoint, the outdoor air damper closes to its minimum
position. A call for cooling from the space thermostat turns on
the mechanical cooling.
During the unoccupied period, the M7415 Damper Actuator
spring-returns the outdoor air damper to the fully closed position.

SETTINGS AND ADJUSTMENTS

Adjusting Minimum Damper Position
The minimum position potentiometer keeps the outdoor air
damper from completely closing during system operation to
allow ventilation.
M7415 and M8405 Damper Actuators
Adjusting Minimum Position (Ventilation)
The M7415 Damper Actuator is adjusted for desired minimum
position using a Q709 Actuator Mounted Minimum Position
Potentiometer and/or a remote S963B1136 Manual
Potentiometer. The M8405 Damper Actuator has an integral
thumbwheel for minimum position adjustment.
M7415 Minimum Position Adjustment
Run actuator to fully closed position and disconnect
24 Vac from terminals TR and TR1.
Connect minimum position potentiometer to terminals P
and P1 (T and T1 are disconnected).
Reconnect 24 Vac to terminals TR and TR1 and adjust
the potentiometer for the desired minimum position.
When the Q709 Actuator Mounted Minimum Position
Potentiometer is used and a remote potentiometer is
not connected in series, jumper terminals P and P1 on
the Q709A.
M8405 Minimum Position Adjustment
Connect the 24 Vac to the actuator at terminals T and X
(D is not connected).
Adjust the thumbwheel on the actuator for desired
minimum position.
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