Modine Manufacturing DBS Installation And Service Manual page 31

COMPONENT DESCRIPTIONS
the space pressure controller energizes the actuator to
drive the fresh air damper closed. When below the desired
low pressure setpoint, a contact on the space pressure
controller energizes the actuator to drive the fresh air
damper open. When the space pressure is between the
high and low setpoints, the damper remains at the fresh air
percentage that satisfied the space pressure controller. Full
90° rotation of the floating actuator requires 150 seconds.
For additional information on the space pressure controller,
refer to Literature 5-585.
The actuator is designed to "float" and therefore is not
spring return. When the unit is de-energized under normal
operation, the fresh air damper is powered closed. If the
supply power to the unit is interrupted before the damper
actuator can drive closed, the fresh air damper will remain
open.
(31) Enthalpy Controller – (OPT) (All Except Model Digit 12=9)
An enthalpy controller is provided with Air Control option (Model
Digits 20-21=GJ). The purpose of the enthalpy controller is to
use outside air for free cooling, whenever possible, to reduce
compressor operation of the mechanical cooling system.
The economizer functions as a true first stage of cooling and
minimizes energy usage during the cooling cycle.
The components used for the Enthalpy Economizer are:
• Enthalpy Economizer Controller. The controller is used in
conjunction with the Enthalpy Sensor and a Mixed Air
Temperature sensor. The controller is factory mounted in
the blower control cabinet.
• Outside Air Enthalpy Sensor. The sensor provides a
signal in relation to enthalpy (temperature and humidity) of
the outside air and is installed in the outside air stream.
• Mixed Air Temperature Sensor. The sensor is factory
installed in the blower section to sense the mixed air
temperature of the fresh and return air streams.
For complete details on the Enthalpy Economizer controller
setup and sequence of operation, please refer to Literature
5-598, latest revision.
Enthalpy Controller
For units with the Modine Control System option (Model Digit
12=9), when the damper control is enthalpy economizer, Model
Digits 20-21 will always be GA and the control will be integral to
the Modine Control System control logic. Refer to the latest
revision of the Modine Control System Manual, literature 74-510
for additional information.
(32) Damper to Damper Linkage – (OPT)
Units with fresh and return air dampers include a damper
actuator that controls the fresh air damper. The return air
damper position is controlled by the fresh air damper through
the connecting rod. For adjustment, refer to Damper Linkage
Adjustment.
(33) Return Air Damper – (OPT)
When a return air damper is supplied with the unit, the damper
is factory installed in the blower section. The return air damper is
used as an air balancing damper so low leak, Class III leakage
resistance (less than 40 CFM/ft² at 1" W.C.) dampers with self-
compensating stainless steel side seals and santoprene blade
seals are used.
(34) Proportional Temperature Controller Sensor – (OPT)
A proportional temperature controller sensor is provided with
Air Control options GG or GH (Digits 20 & 21) and factory
installed in the blower section. The sensor provides the mixed
air temperature signal to the A350P Proportional Temperature
Controller which is mounted in the electrical section. See
Option #42 for complete description of option.
(35) Motor and Blower Vibration Isolation – (STD)
The motor vibration isolation is factory installed below the
blower support bracket. The four (4) neoprene vibration mount
grommet provides isolation of the blower housing and motor
from the blower support channels. The blower duct connection
is not rigidly mechanically fastened and the 1/4'' thick gasketing
around the duct transition provides vibration isolation.
Blower/Motor Vibration Isolation
(36) Blower Support – (STD)
The blower supports are factory installed in the blower section.
The blower supports are used to rigidly support the weight of the
blower and motor during operation and shipping.
5-594.10
BLOWER
SUPPORT
BLOWER
SUPPORT
RAIL
NEOPRENE
VIBRATION
ISOLATOR
31