Installation manual

IM-487 Page 23
3. Locate the duct pressure (HI) tap near the end of a long
duct to verify that all terminal box take-offs along the run
will have adequate static pressure.
4. Locate the duct tap in a nonturbulent flow area of the duct.
Keep it several duct diameters away from take-off points,
bends, neckdowns, attenuators, vanes, or other irregularities.
5. Use a static pressure tip (Dwyer A302 or equivalent) or the
bare end of the plastic tubing for the duct tap. (If the duct is
lined inside, use a static pressure tip device.)
6. Install the duct tap so that it senses only static pressure (not
velocity pressure). If an L-shaped pressure tip device is
used, the point must face the airstream. If a bare tube end
is used, it must be smooth, square (not cut at an angle), and
perpendicular to the airstream.
(see Figure 25).
7. Locate the reference pressure (LO) tap somewhere near
the duct pressure tap within the building (see Figure 24). If
the reference tap is not connected to the sensor, unsatisfac-
tory operation will result.
8. Route the tubes between the curb and the supply duct, and
feed them into the unit through the knockout in the bottom
of the control panel (see Figure 24). Connect the tubes to
the appropriate 1/8 inch fittings on the sensors. Make sure
that the sensors do not support the weight of the tubing;
use tube clamps or some other means.
Figure 24. Static Pressure Tubing Entrance Location
Figure 25. Pressure Sensing Tubing Installation
Installing Building Static
Pressure Sensor Taps
If a unit has direct building static pressure control capability,
static pressure taps must be field installed and connected to
pressure sensor SPS2 in the unit. This sensor is located at the
bottom of the main control panel next to terminal block TB2
(see "Control Panel Locations" in the "Unit Description" sec-
tion of this manual).
The two static pressure sensing taps must be carefully located
and installed. Improper location or installation of the sensing
taps will cause unsatisfactory operation. Following are pres-
sure tap location and installation recommendations for both
building envelope and lab, or "space within a space," pressure
control applications. The installation must comply with local
code requirements.
M a i n
C o n t r o l
P a n e l
O u t d o o r S t a t i c
P r e s s u r e T u b i n g
E n t r a n c e ( F i e l d C u t )
I n d o o r S t a t i c
P r e s s u r e T u b i n g E n t r a n c e
C o n t r o l W i r i n g
R a c e w a y C o v e r
CAUTION
Fragile sensor fittings.
May damage pressure sensor.
If tubing must be removed from a pressure sensor fitting,
use care. Do not wrench the tubing back and forth to
remove or the fitting may break off.
M a i n C o n t r o l P a n e l
C o n d e n s e r S e c t i o n
" H I l i n e "
" L O " l i n e
R e m o t e S e n s e P o i n t
S P S 1
R o o f
T u b i n g E x t e n d s
t h r u A p p r o x . 1 / 8 "
R u b b e r
G r o m m e t
D u c t w o r k
( R e m o t e L o c a t i o n )
T o S e n s o r
" H I " i n p u t
T o S e n s o r
" L O " I n p u t
P r e s s u r e S e n s i n g
T u b i n g