Operation - Bryant Legacy 704D--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 closed (CCW)
when not using CO sensor.
2
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
Table 16 – CO
OUTPUT
Proportional
Proportional
Exponential
Proportional
Proportional
Exponential
Exponential
Proportional
Proportional
Table 17 – 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
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
Economizer control, a demand controlled ventilation strategy will
begin to operate. As the CO
CO set point, the minimum position of the damper will be
2
increased proportionally. As the CO
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.
46
CO OPTIONAL
2
CONTROL RELAY
HYSTERESIS
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
2
level in the zone increases above the
2
level decreases because of the
2
RELAY
(PPM)
50
50
50
50
50
50
50
500
50