46
McQuay IM 987
Mechanical Installation
Installing Duct Static Pressure Sensor Taps
For all VAV units, field install and connect duct static pressure
taps to the pressure sensors in the unit. Sensor SPS1 is
standard; additional sensor SPS2 is optional. These sensors are
located in the main control panel (see
"Control Panel"‚ page
5
).
Carefully locate and install the duct static pressure sensing tap.
Improperly locating or installing the sensing tap causes
unsatisfactory operation of the entire variable air volume
system. Below are pressure tap location and installation
recommendations. The installation must comply with local
code requirements
1
Install a tee fitting with a leak-tight removable cap in
each tube near the sensor fitting. This facilitates
connecting a manometer or pressure gauge if testing is
required.
2
Use different colored tubing for the duct pressure (HI)
and reference pressure (LO) taps, or tag the tubes.
McQuay recommends 1/4" plastic tubing.
3
Locate the duct pressure (HI) tap near the end of a long
duct to ensure that all terminal box take-offs along the
run 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 a bare tube end is used, it must
be smooth, square (not cut at an angle) and perpendicular
to the airstream (see
Figure 54
).
7
Locate the reference pressure (LO) tap somewhere near
the duct pressure tap within the building (see
Figure 53
).
If the reference tap is not connected to the sensor,
unsatisfactory 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 53
). Connect the
tubes to appropriate barbed fittings in the control panel.
(Fittings are sized to accept 1/4" plastic tubing.)
Figure 53: Static Pressure Tubing Entrance Location
Figure 54: Pressure Sensing Tubing Installation
Static pressure
tubing
Main Control Panel
"HI line"
"LO" line
Remote Sense Point
SPS1
Roof
Tubing Extends
thru Approx. 1/8"
Rubber
Grommet
Ductwork
(Remote Location)
To Sensor
"HI" input
To Sensor
"LO" Input
Pressure Sensing
Tubing
Содержание RAH 047C
Страница 70: ...70 McQuay IM 987 Wiring Diagrams Figure 78 VAV Control Inputs Schematic continues on next page ...
Страница 71: ...McQuay IM 987 71 Wiring Diagrams Figure 79 VAV Control Inputs Continued Schematic continues on previous page ...
Страница 74: ...74 McQuay IM 987 Wiring Diagrams Figure 82 VFD Control SAF and RAF Schematic continues on next page ...
Страница 104: ...104 McQuay IM 987 Final Control Settings Figure 117 Keypad Accessible Menu Structure ...
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