Bryant LEGACY 604D-A, Installation Instructions Manual

Page: 49 / 52

49
Table 16 – CO
2
Sensor Standard Settings
SETTING EQUIPMENT OUTPUT
VENTILATION
RATE
(CFM/
PERSON)
ANALOG
OUTPUT
CO
2
CONTROL
RANGE
(PPM)
OPTIONAL
RELAY
SETPOINT
(PPM)
RELAY
HYSTERESIS
(PPM)
1 Proportional Any
0---10V
4---20mA
0---2000 1000 50
2
Interface w/Standard Building
Control System
Proportional Any
2---10V
7---20mA
0---2000 1000 50
3 Exponential Any
0---10V
4---20mA
0---2000 1100 50
4 Proportional 15
0---10V
4---20mA
0---1100 1100 50
5 Economizer Proportional 20
0---10V
4---20mA
0---900 900 50
6 Exponential 15
0---10V
4---20mA
1---1100 1100 50
7 Exponential 20
0---10V
4---20mA
0---900 900 50
8 Health & Safety Proportional ---
0---10V
4---20mA
0---9999 5000 500
9 Parking/Air Intakes/Loading Docks Proportional ---
0---10V
4---20mA
0---2000 700 50
Table 17 – CO
2
Sensor Standard Settings Economizer Input/Output Logic
INPUTS OUTPUTS
DEMAND
CONTROL
VENTILATION
(DCV)
ENTHALPY
Y1 Y2
COMPRESSOR N TERMINAL
OUTDOOR RETURN
STAGE
1
STAGE
2
OCCUPIED UNOCCUPIED
DAMPER
Below set (DCV
LED Off)
High (Free Cooling
LED off)
Low
On On On On
Minimum position Closed On Off On Off
Off Off Off Off
Low (Free Cooling
LED on)
High
On On On Off
Modulating** (between min.
position and full---open)
Modulating** (between closed
and full---open)
On Off Off Off
Off Off Off Off Minimum position Closed
Above set (DCV
LED On)
High (Free Cooling
LED off)
Low
On On On On
Modulating
{{
(between
min. position and DCV
maximum)
Modulating
{{
(between closed
and DCV maximum)
On Off On Off
Off Off Off Off
Low (Free Cooling
LED on)
High
On On On Off
Modulating*** Modulating
{{{
On Off Off Off
Off Off Off Off
* For single enthalpy control, the module compares outdoor enthalpy to the ABCD set point.
{
Power at N terminal determines Occupied/Unoccupied setting: 24 vac (Occupied), now power (Unoccupied).
**Modulating is based on the supply--- air sensor signal.
{{
Modulation is based on the DCV signal.
***Modulation is based on the greater of DCV and supply--- air sensor signals, between minimum position and either maximum position (DCV) or fully open (supply--- air signal).
{{{
Modulating is based on the greater of DCV and supply--- air sensor signals, between closed and wither maximum position (DCV) or fully open (supply--- air signal).
OPERATION
Sequence of Operation— When free cooling is not available, the
compressor will be controlled by the thermostat. When free cooling
is available, the outdoor--air damper is modulated by the Economizer
control to provide a 50
_
to 55
_
F (10
_
to 12.8
_
C) supply--air
temperature into the zone. As the supply--air temperature fluctuates
above 55
_
(12.8
_
C) or below 50
_
F (10
_
C), the dampers will be
modulated (open or close) to bring the supply--air temperature back
within the set points. For Economizer operation, there must be a
thermostat call for the fan (G). This will move the damper to its
minimum position during the occupied mode.
NOTE
: The DCV Max potentiometer must be closed (CCW)
when not using CO
2
sensor.
Above 50
_
F (10
_
C) supply--air temperature, the dampers will
modulate from 100% open to the minimum open position. From
50
_
F to 45
_
F (10
_
to 7.2
_
C) supply--air temperature, the dampers
will maintain at the minimum open position. Below 45
_
F (7.2
_
C),
the dampers will be completely shut. As the supply--air temperature
rises, the dampers will come back open to the minimum open
position once the supply--air temperature rises to 48
_
F (8.9
_
C). If
power exhaust is installed, as the outdoor--air damper opens and
closes, the power exhaust fans will be energized and deenergized.
If field--installed accessory CO
2
sensors are connected to the
Economizer control, a demand controlled ventilation strategy will
begin to operate. As the CO
2
level in the zone increases above the
CO
2
set point, the minimum position of the damper will be
increased proportionally. As the CO
2
level decreases because of the
increase in fresh air, the outdoor--air damper will be proportionally
closed. Damper position will follow the higher demand condition
from DCV mode or free cooling mode. Damper movement from
full closed to full open (or vice versa) will take between 1 1/2 and
2 1/2 minutes. If free cooling can be used as determined from the
appropriate changeover command (dry bulb, enthalpy curve, or
differential enthalpy), a call for cooling (Y1 closes at the
thermostat) will cause the control to modulate the dampers open to
maintain the supply air temperature set point at 50
_
to 55
_
F (10
_
to 12.8
_
C). As the supply air temperature drops below the set point
range of 50
_
to 55
_
F (10
_
to 12.8
_
C), the control will modulate
the outdoor--air dampers closed to maintain the proper supply--air
temperature.
604D
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--
A