Operation - Bryant Legacy 574D----A Installation Instructions Manual

SETTING EQUIPMENT
1
Interface w/Standard Building
2
Control System
3
4
5 Economizer
6
7
8 Health & Safety
9 Parking/Air Intakes/Loading Docks
INPUTS
DEMAND ENTHALPY
CONTROL
VENTILATION
OUTDOOR
(DCV)
High (Free Cooling
LED off)
Below set (DCV
LED Off)
Low (Free Cooling
LED on)
High (Free Cooling
LED off)
Above set (DCV
LED On)
Low (Free Cooling
LED on)
* 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 colosed (CCW)
2
when not using CO 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
Table 21 – CO
OUTPUT
Proportional
Proportional
Exponential
Proportional
Proportional
Exponential
Exponential
Proportional
Proportional
Table 22 – CO Sensor Standard Settings Economizer Input/Output Logic
2
Y1 Y2
RETURN
On On
Low On Off
Off Off
On On
High On Off
Off Off
On On
Low On Off
Off Off
On On
High On Off
Off Off
Sensor Standard Settings
2
VENTILATION
RATE
ANALOG
(CFM/ OUTPUT
PERSON)
0--- 10V
Any
4--- 20mA
2--- 10V
Any
7--- 20mA
0--- 10V
Any
4--- 20mA
0--- 10V
15
4--- 20mA
0--- 10V
20
4--- 20mA
0--- 10V
15
4--- 20mA
0--- 10V
20
4--- 20mA
0--- 10V
---
4--- 20mA
0--- 10V
---
4--- 20mA
COMPRESSOR
OCCUPIED
STAGE STAGE
1 2
On On
On Off Minimum position
Off Off
On Off
Modulating** (between min.
position and full ---open)
Off Off
Off Off Minimum position
On On
Modulating{{ (between
On Off min. position and DCV
maximum)
Off Off
On Off
Off Off Modulating***
Off Off
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
control, a demand controlled ventilation strategy will begin to
operate. As the CO
point, the minimum position of the damper will be increased
proportionally. As the CO
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.
56
CO OPTIONAL
2
CONTROL RELAY
RANGE SETPOINT
(PPM) (PPM)
0--- 2000 1000
0--- 2000 1000
0--- 2000 1100
0--- 1100 1100
0--- 900 900
1--- 1100 1100
0--- 900 900
0--- 9999 5000
0--- 2000 700
OUTPUTS
N TERMINAL
UNOCCUPIED
DAMPER
Closed
Modulating** (between closed
and full ---open)
Closed
Modulating{{ (between closed
and DCV maximum)
Modulating{{{
sensors are connected to the Economizer
2
level in the zone increases above the CO
2
level decreases because of the increase in
2
RELAY
HYSTERESIS
(PPM)
50
50
50
50
50
50
50
500
50
set
2