Reznor X Unit Installation Manual - Manual (Page 15)

Form I-X, P/N 150491 R10, Page 15
6.3.5 Discharge Air
Sensor for Makeup
Air Application
Makeup air Option AG3 has a unit mounted ductstat with a capillary sensor that is
factory-installed in the unit discharge (See Paragraph 8.4.3).
Makeup air Options AG8, AG9, and AG15 require field installation of the sensor in the
discharge ductwork. Option AG15 uses the box and sensor holder in FIGURE 15A.
Options AG8 and AG9 include a sensor and mixing tube as illustrated in FIGURE 15B.
Follow the instructions below to install the sensor in the ductwork.
For control information, see Paragraph 8.4.
FIGURE 15A -
Discharge Air Sensor
Holder, P/N 115850,
used in Makeup Air
Option AG15
Secure sensor in clip.
Position holder so that it
shields sensor from direct
airflow.
Instructions for Installing Discharge Air Sensor in the Ductwork
1. Depending on the option, the sensor will be as shown in either FIGURE 15A or
15B. See Paragraph 3.2 for a list of shipped-separate components by option.
2. Determine a location in the ductwork to install the sensor.
Select a location a sufficient distance from the outlet to provide a good mixture of
discharge air temperature. According to the latest edition of AMCA Standard 201,
in straight ducts, the air is typically well mixed a minimum of five equivalent duct
diameters from the discharge of the unit with equivalent duct diameter defined
as equal to the square root of 4AB/3.14. "A" and "B" are the duct cross-sectional
dimensions.
Example: Supply ductwork cross-sectional dimension is
24" x 12" (610mm x 305mm).
5 x
4 x 12 x 24
3.14
= 96" 5 x
4 x 305 x 610
3.14 = 2435mm
Solution: Locate the sensor a minimum of 96" (2435mm)
from the outlet of the unit.
NOTE: If the length of the discharge duct is less than 8 ft (2.4M), a mixing vane is
recommended for mixing the discharge air.
Do not mount the sensor in the ductwork after a split in the supply as that will
cause loss of control in the duct that does not house the sensor.
3. The position of the sensor holder or mixing tube is important. The holder in
FIGURE 15A will extend 9-3/16” (233mm) into the ductwork. The mixing tube in
FIGURE 15B is 12" (305mm) long.
In horizontal ductwork, locate the sensor assembly in the top, middle of the duct
with the sensor probe extending vertically down into the center of the airstream.
In vertical ductwork, locate the sensor assembly in the middle of the side of the
duct that corresponds with the top middle of the discharge outlet.
Turn the holder so that the element will be shielded from direct airflow and will
sense the air temperature as it flows through the holes in the holder.
At the selected location in the ductwork, mark the diamond-shaped hole
[approximately 1” x 1” (25mm x 25mm)] required for the sensor holder or the round
hole needed for the mixing tube. Cut the hole no larger than required.
4. Option AG15 - Push the element into the clip in the holder. Determine where the
sensor wire should enter the box and remove the knockout. Slide the holder into
the ductwork. Using four field-supplied No. 6 sheetmetal screws, attach the box
portion of the holder to the ductwork. Attach a field-supplied cable connector to the
box, connect the sensor wire, and attach the box cover.
Options AG8 and AG9 - Slide the mixing tube into the ductwork and attach the
sensor. Connect the wires as shown on the wiring diagram.
FIGURE 15B -
Discharge Air Sensor
and Mixing Tube
used in Electronic
Modulation Options
AG8 and AG9