Stulz E2 Series User Manual

STULZ E
2
SERIES CONTROLLER FOR PERIMETER SYSTEMS OPERATION MANUAL
47
6.0 ECONOMIZER OPERATION
An economizer mode is available for applications utilizing
outdoor air-side economizing. The E² controller manages the
economizer mode to utilize outside air and minimize the need for
conventional cooling. It also monitors the outside air dewpoint
so as to not introduce air that is either too wet or dry for the
desired conditions. To enable economizer operation, an outside
air temperature/humidity sensor and a return air temperature/
humidity sensor are provided to control the economizer damper
system (see Figure 9). The economizer mode is to be used with
an opposing pair damper set-up, i.e. when the external outside
air intake damper is set at 30% open, the room return damper
moves to 70% open.
Blower
Mixed Air
Filter
Outside Air Intake
Damper
Room Return Air
Damper
Room Return
T
emperature/Humidity
Sensor
Coil
Temperature/Humidity Sensor
Outside Air
Temperature/Humidity
Sensor
Supply Air
Temperature/Humidity Sensor
The controller only provides a single output signal intended to
control the outside air damper. It is up to the designer of the
damper system to use that signal to control a reverse-acting
room return air damper. If the room return air damper is not
interlocked to run in reverse or if it is missing altogether, true
100% outside air can not be achieved.
NOTE:
The mixed air sensor is the return air sensor inside the
A/C unit.
A proportional control signal (110 VDC) allows the external
outdoor air intake damper and room return air damper to
modulate their positions between 0100% open to maintain
user supply air setpoints. The controller seeks to achieve the
most energy effi cient mixture of outside air and return air to
satisfy the temperature/humidity demand and maintain the
setpoints. Damper control settings are determined by examining
both the temperature and dewpoint properties of the outdoor
air and the return air. The outdoor air damper output signal will
lockout if the outdoor air temperature or dewpoint lie outside
of the user adjustable setpoint values. A return air (mixed air)
sensor is included to limit economizer function if low limit alarms
are reached.
The economizer damper signal can be adjusted to a minimum
output value to allow only the least amount of outside air to enter
for meeting air quality ventilation requirements.
Figure 9. Economizer Operation

Stulz E2 Series Specifications

General

Brand	Stulz
Model	E2 Series
Category	Controller
Language	English