Bryant DuraPac Series 580f - Manual (Page 23)

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minimum position (configuration item number 15), unless
the remote potentiometer is used to override it.
For the demand ventilation control logic, the user configures
the lower and upper actuator position to establish the base
ventilation rate (IAQMIN_SP) and the design ventilation
rate (ECONOMIN_SP) for full occupancy. When the
EconoMi$er+ damper is being modulated for demand venti-
lation control, the damper position will be between
IAQMIN_SP and ECONOMIN_SP. The upper IAQ differen-
tial set point is DAQHI. The lower IAQ differential set point
is DAQLO.
The differential set points represent the differential CO
2
level (in ppm) above the outdoor reference IAQ levels.
Normally, the outdoor reference IAQ levels are around
400 ppm, but the value should be configured based on the
reference levels taken at the job site.
The following equation is used to determine EconoMi$er+
damper position (ECONOMIN_POS):
R. CO
2
Sensor Configuration
The CO
2
sensor has preset standard voltage settings that
can be selected anytime after the sensor is powered up. See
Table 7.
1. Press Clear and Mode buttons. Hold at least 5 sec-
onds until the sensor enters the Edit mode.
2. Press Mode 2 times. The STDSET Menu will appear.
3. Use the Up/Down button to select the preset number.
See Table 7.
4. Press Enter to lock in the selection.
Press Mode to exit and resume normal operation. The cus-
tom settings of the CO
2
sensor can be changed any time
after the sensor is energized. Follow the steps below to
change the non-standard settings:
1. Press Clear and Mode buttons. Hold at least 5 sec-
onds until the sensor enters the Edit mode.
2. Press Mode 2 times. The STDSET Menu will appear.
3. Use the Up/Down button to toggle to the NONSTD
menu and press Enter.
4. Use the Up/Down button to toggle through each of
the nine variables, starting with Altitude, until the
desired setting is reached.
5. Press Mode to move through the variables.
6. Press Enter to lock in the selection, then press Mode
to continue to the next variable.
S. Dehumidification of Fresh Air with Demand Control Ven-
tilation (DCV)
Information from ASHRAE (American Society of Heating,
Refrigeration and Air Conditioning Engineers) indicates that
the largest humidity load on any zone is the fresh air intro-
duced. For some applications, a device such as a energy
recovery unit is added to reduce the moisture content of the
fresh air being brought into the building when the enthalpy
is high. In most cases, the normal heating and cooling pro-
cesses are more than adequate to remove the humidity loads
for most commercial applications.
This makes the control of the dehumidification device simple
when using the enthalpy or differential enthalpy sensor. The
enthalpy sensor or differential enthalpy sensor is installed
on the equipment to determine economizer operation. The
high enthalpy signal from the temperature and humidity
sensors or differential temperature and humidity sensors
can be used to turn on the outdoor air moisture removal
device any time fresh air is required for the space.
The energy recovery device should be sized for maximum
latent and sensible conditioning at maximum ventilation on
a design day.
A calculation for leaving-air temperature on a low ambient,
low ventilation day should also be done to determine the
supply-air temperature of the return and pre-conditioned
outside air. The design should produce air temperature
somewhat near room conditions to prevent reheat of the air
mixture. The energy recovery device should be interlocked
with the heat to turn off the device when in the heat mode.
Table 7 — CO
2
Sensor* Standard Settings
LEGEND
*Available sensor part numbers are listed in Table 4.
IAQMIN_SP + =
(ECONOMIN_SP – IAQMIN_SP) * (IAQ – OAQ – DAQLO)
(DAQHI – DAQLO)
SETTING EQUIPMENT OUTPUT
VENTILATION
RATE
(cfm/Person)
ANALOG
OUTPUT
CO
2
CONTROL
RANGE (ppm)
OPTIONAL
RELAY SETPOINT
(ppm)
RELAY
HYSTERESIS
(ppm)
1
Interface with Standard
Building Control System
Proportional Any 4-20 mA 0-2000 1000 50
2 Proportional Any 7-20 mA 0-2000 1000 50
3 Exponential Any 4-20 mA 0-2000 1100 50
4
Economizer
Proportional 15 4-20 mA 0-1100 1100 50
5 Proportional 20 4-20 mA 0- 900 900 50
6 Exponential 15 4-20 mA 0-1100 1100 50
7 Exponential 20 4-20 mA 0- 900 900 50
8 Health & Safety Proportional — 4-20 mA 0-9999 5000 500
9 Parking/Air Intakes/ Loading Docks Proportional — 4-20 mA 0-2000 700 50
ppm — Parts Per Million
100
500 700
1100
INSIDE/OUTSIDE CO 2 DIFFERENTIAL
INSIDE CO 2 CONCENTRATION
AQ
DIFFERENTIAL
LOW (DAQLO) AQ
DIFFERENTIAL
HIGH (DAQHI)
IAQ
MINIMUM
ECONOMIZER
POSITION
SET POINT
(IAQMIN_SP)
ECONOMIZER
MINIMUM
OCCUPIED
DAMPER
POSITION
(ECONOMIN_SP)
VENTILATION FOR PEOPLE
VENTILATION FOR SOURCES
FULL OCCUPANCY
VENTILATION RATE
DAMPER
POSTION
CO LEVEL 2
OUTDOOR REFERENCE
LEVEL (OAQ)= 400
Fig. 32 — Demand Ventilation Control