RT-SVX063E-EN
53
Table 19.
Return air pressure increase (continued)
CFM
Return Air Damper Position
#1
#2
#3
#4
12000
0.00
0.10
0.22
0.33
14000
0.00
0.11
0.25
0.43
16000
0.00
0.13
0.28
0.55
18000
0.00
0.14
0.31
0.67
20000
0.00
0.15
0.33
0.81
22000
0.00
0.16
0.35
0.96
24000
0.00
0.17
0.37
1.13
Units with Dual Actuators (60, 70 and 75
Ton)
The installer can adjust the stroke of the direct drive
actuator on the O/A & R/A dampers to compensate for
various R/A duct losses.
Table 20, p. 53
and
Table 21,
p. 54
list the pressure drops for various actuator limit
positions based on the air flow (CFM) and
configuration. The actuator stroke limit can be adjusted
between 33% and 100% of full stroke. To adjust the O/A
or R/A damper for the correct pressure drop:
1. Drill a 1/4" hole through the unit casing up stream
of the return air dampers. Use a location that will
produce an accurate reading with the least amount
of turbulence – several locations may be necessary,
then average the reading.
2. Measure the return duct static pressure.
3. Compare the static pressure reading to the static
pressure ranges and linkage positions in
Table 20,
p. 53
or
Table 21, p. 54
for the unit configuration,
unit size and operating CFM.
If the static pressure reading is greater than the
pressure listed in
Table 20, p. 53
or
Table 21, p. 54
for outside air damper position 100% then adjust
the outside air damper actuator to balance the
outside air damper pressure drop against the return
static pressure, using the following steps.
If the static pressure reading is less than the
pressure listed in
Table 20, p. 53
or
Table 21, p. 54
for outside air damper position 100%, then
determine the appropriate return air pressure drop
increase needed. Identify the correct return damper
actuator position using
Table 22, p. 54
. Then, adjust
the return air damper actuator to balance the
outside air damper pressure drop against the return
static pressure using the following steps.
If no adjustment is necessary, proceed to step 6.
4. To set the actuator stroke limit:
a. Loosen the screw that secures the angle of
rotation limiter on the actuator adjacent to the
damper drive shaft clamp.
b. Move the limiter to the desired % open position
and, making sure the limiter teeth are engaged,
retighten the screw.
5. After setting the end stop, the actuator needs to be
cycled through its auto-adapt feature to re-scale the
control range. With 24 VAC power applied to the
actuator, turn the control signal reversing switch
forward and back again two times. Within a few
seconds, the actuator will cycle itself to the new
limiter position and then back to zero.
N
No
otte
e:: This process may take up to 5 minutes.
The actuator will then be set to respond to the 2-10
VDC control signal to cycle within the new range of
rotation set by the limiter. Verify that the control
signal reversing switch is set back to its original
default position - Y = 0, set to CCW, which is the
same direction as spring return.
6. Plug the holes (made during Step 1) after the proper
adjustments have been made.
Table 20.
Outside Air Pressure Drop (inches w.c.) – No Traq
™
™
No Traq
™
™
CFM
Outside Air Damper Position
100%
75%
55%
45%
33%
60, 70 and 75 Ton
14000
0.16
0.30
0.43
0.60
1.10
16000
0.20
0.39
0.57
0.80
1.52
IIn
nsstta
alllla
attiio
on
n
