23
damper minimum position will increase or decrease, respectively .
This relationship curve is shown in Fig. 16.
NOTE: The software point names are used in Fig. 16 as to not
clutter the graph. These points are not individually set and
therefore only visible from a network for troubleshooting.
These units can also be equipped with optional CO
2
sensors for
additional indoor air quality control. When unit is equipped with a
return duct CO
2
sensor or return duct CO
2
sensor and outside air
CO
2
sensor the Economizer minimum position vs. fan speed curve
will be recalculated based on the CO
2
level of the return and/or
outside air as shown in Fig. 16. When performing Demand
Controlled Ventilation, the damper’s Min Position in Effect
(EFFECTIVE MIN POS) will operate in the shaded area of Fig.
16 based on the IAQ Level (IAQ) and the Commanded Fan Speed
(IDF SPEED OUTPUT). See the Indoor Air Quality (IAQ)
section for more details on Demand Controlled Ventilation (DCV).
The damper position curve can be field adjusted per application if
needed.
1. Activate test mode to control the fan and dampers to
achieve the correct numbers.
2. Set the fan speed for the maximum amount needed for
design CFM requirements. This should also be the IDF
maximum Fan speed (IDF MAXSPEED).
3. Open the damper to the position which satisfies the highest
ventilation requirement running maximum fan speed, and
then set the Economizer minimum at maximum fan speed
(MIN POS @ MAX FAN) to this damper position.
4. Set the fan speed to a realistic operating speed in the upper
range, and then set the User Minimum Position Speed 1
(MIN POS SPEED 1) equal to that speed. This should be
somewhere in the 80% range.
5. Open the damper to the position which satisfies the highest
ventilation requirement running speed 1 fan speed, and then
set the User Minimum Position Damper Position 1 (MIN
POS DAMP 1) to this damper position.
6. Set the fan speed to a realistic operating speed in the mid--
range, and then set the User Minimum Position Speed 2
(MIN POS SPEED 2) equal to that speed. This should be
somewhere in the 60% range.
7. Open the damper to the position which satisfies the highest
ventilation requirement running speed 2 fan speed, and then
set the User Minimum Position Damper Position 2 (MIN
POS DAMP 2) to this damper position.
8. Set the fan speed to a realistic operating speed in the low--
range, and then set the User Minimum Position Speed 3
(MIN POS SPEED 3) equal to that speed. This should be
lowest fan speed in planned operating range.
9. Open the damper to the position which satisfies the highest
ventilation requirement running speed 3 fan speed, and then
set the User Minimum Position Damper Position 3 (MIN
POS DAMP 3) to this damper position.
The shape of the curves in Fig. 16 are determined by the
configuration parameters: User Minimum Position Speed 1 (MIN
POS SPEED 1), User Minimum Position Damper Position 1
(MIN POS DAMP 1), User Minimum Position Speed 2 (MIN
POS SPEED 2), User Minimum Position Damper Position 2
(MIN POS DAMP 2), User Minimum Position Speed 3 (MIN
POS SPEED 3), User Minimum Position Damper Position 3
(MIN POS DAMP 3), and Economizer minimum at maximum fan
speed (MIN POS @ MAX FAN). These configurations are preset
at the factory of default purposes. The Economizer minimum at
maximum fan speed (MIN POS @ MAX FAN) should be changed
based on the air balance of the unit for proper ventilation.
The user adjustable points discussed above are defaulted to zero
from the factory which forces the control to use a set of default
points. The default points should not be left for permanent
operation, as it may cause inadequate ventilation. Economizer
minimum at maximum fan speed (MIN POS @ MAX FAN) and at
least one set of user points User Minimum Position Speed 1 (MIN
POS SPEED 1) and User Minimum Position Damper Position 1
(MIN POS DAMP 1) should be used to create a linear curve to
cover the broad scope of fan operation.
Econo Max
Position
(DAMPMAX)
Damper Position
Indoor Fan Speed
Maximum Speed
(SPEEDMAX)
10%
MINP_MAX
(MP_SPD3,
MP_POS3)
(MP_SPD2,
MP_POS2)
(MP_SPD1,
MP_POS1)
Key
:
Minimum Position Curve
IAQPMAX
(AQP_SPD3,
AQP_POS3)
(AQP_SPD2,
AQP_POS2)
(AQP_SPD1,
AQP-POS1)
IAQ Purge Position Curve
IAQMINP
(AQ_SPD3,
AQ_POS3)
(AQ_SPD2,
AQ_POS2)
(AQ_SPD1,
AQ_POS1)
IAQ Minimum Position Curve
C14326
Fig. 16 -- Minimum Damper Position Curves
To Next Page
Loading...
