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4.
MIN POS
- Outside Air Damper minimum position
a.
Displays ONLY if a CO
2
sensor is NOT connected.
With 2-speed fan units MIN POS L (low speed fan)
and MIN POS H (high speed fan) settings are
required. Default for MIN POS L is 3.2V and MIN
POS H is 2.8V.
b.
Adjust MIN POS to allow the minimum amount of
outdoor air, as required by local codes, to enter the
building.
c.
Range of adjustment is from 0-100% (2-10V); in
most applications MIN POS is adjusted to allow
10% to 25% outside air to enter the system.
d.
MIN POS can be adjusted at any time.
e.
Whenever the “G” (supply fan) signal is present,
the damper will open to this minimum position
unless the mixed air sensor falls below the MA LO
SET (Freeze Protect Mode Setpoint).
5.
VENTMAX
- Demand Control Ventilation (DCV)
Maximum Setpoint
a.
Displays only if a CO
2
sensor is connected.
b.
VENTMAX allows the installer to limit the amount
of outdoor airflow into the building when DCV
overrides the mixed air temperature sensor
setpoint. It is normally equal to the minimum
a m o u n t o f o u td o o r a i r u n d e r m a x i m u m
occupancy, as required by local codes, to enter
the building.
c.
VENTMAX can be adjusted at any time.
6.
VENTMIN
- Demand Control Ventilation (DCV)
Setpoint
a.
Displays only if a CO
2
sensor is connected.
b.
Is the ventilation requirement for less than
maximum occupancy of the space.
c.
Compatible CO
2
sensors will have a 2-10Vdc
output for a 0-2000 ppm CO
2
input.
d.
DCV modulates the outdoor damper between the
VENTMIN and VENTMAX settings to provide
ventilation based on occupancy. The carbon
dioxide (CO
2
) sensor is used to indirectly monitor
occupancy level.
e.
No cooling signal (e.g.Y1, Y2) is required for DCV
to override the outdoor air damper when
ventilation requires outdoor air.
f.
The controller must receive a “G” (supply fan)
signal to open the damper.
g.
Range of adjustment is from 2 Volts to 10 Volts.
h.
VENTMIN can be adjusted at any time.
I.
The controller compares the CO
2
sensor input to
VENT MIN to determine the damper minimum
position.
I.
If the actual CO
2
level is below the setpoint,
then the damper minimum position is
determined by the damper minimum position
(VENTMIN) setting.
ii.
If the actual CO
2
level rises above the
setpoint, then the damper minimum position is
overridden proportionally more open up to the
VENTMAX setting.
iii. If the mixed air temperature drops below 45°F
(MA LO SET - Freeze Protect Mode Setpoint),
the DCV input will be overridden and the
damper may not open.
j.
Ensure proper polarity of the sensor wires when
connecting to the economizer controller. Incorrect
polarity negates the sensor signal.
NOR MAL OP ER A TION
1.
Fan Only (G)
a.
Damper will go to minimum position (in 90
seconds or less) whenever the “G” (supply fan)
signal is present.
b.
When “G” signal is removed, the outside air
damper closes against blade seals for tight shutoff
of outside air.
c.
If the mixed air temperature drops below 45°F (MA
LO SET Setpoint), then the control will override
the minimum position setting and will modulate the
outside air damper closed.
2.
Call for First Stage of Cooling (Y1)
a.
Economizer Unavailable (warm outdoor air):
Closes the Y1-O relay (Y1-O) which energizes 1st
stage compressor.
b.
Economizer Available (free cooling): The
controller tries to maintain a mixed air temperature
of 53°F ± 5 (MAT SET Setpoint) by modulating the
outside air damper position.
3.
Call for Second Stage of Cooling (Y2)
a.
Economizer Unavailable (warm outdoor air):
Closes the Y2-O relay (Y2-O) which energizes
2nd stage compressor.
b.
Economizer Available (free cooling): Closes the
Y1-O relay (Y1-O) which energizes 1st stage
compressor. The controller tries to maintain a
mixed air temperature of 53°F ± 5 (MAT SET
Setpoint) by modulating the outside air damper
position. After a time period of 2 hours of
simultaneous economizer operation and first
stage compressor operation, the economizer
closes the Y2-O relay (Y2-O) which energizes 2nd
stage compressor.
4.
Call for Heat
a.
Standard Air Conditioner with electric or gas heat.
(W1 & W2)
I.
The Thermostat controls the stages of heating
directly.
ii.
If the control detects that the supply fan is on
(through its “G” input), then the control will
open the damper to minimum position.
iii. If the mixed air temperature drops below 45°F
(MA LO SET Setpoint), then the control will
override the minimum position setting and will
modulate the outdoor damper closed.
b.
Heat Pump Operation (B)
I.
The “B” signal from the Thermostat allows
operation of the compressors to provide
heating without delay.
ii.
If the control detects that the supply fan is on
(through its “G” input), then the control can
open the damper to minimum position.
iii. If the mixed air temperature drops below 45°F
(MA LO SET Setpoint), then the control will
override the minimum position setting and will
modulate the outdoor damper closed.
