Reznor HRPD (Outdoor Duct Furnaces) Unit Installation Manual - Manual (Page 13)

Form I-RP/HRPD, P/N 132210 R14, Page 13
7.0 Electrical
Supply and
Connections
7.1 General
WARNING
If you turn off the power supply, turn off the gas. See Hazard
Levels, page 2.
All electrical wiring and connections, including electrical grounding MUST be made in
accordance with the National Electric Code ANSI/NFPA No. 70 (latest edition) or, in
Canada, the Canadian Electrical Code, Part I-C.S.A. Standard C22.1. In addition, the
installer should be aware of and in compliance with any local ordinances or gas com-
pany requirements that might apply.
Instructions for
Installing Discharge Air
Sensor in the Ductwork
1. Depending on the option, the sensor will be as shown in FIGURE 10A, in FIGURE
10B, or field-supplied for Option AG40 or AG42. See Paragraph 3.2 for a list of
shipped-separate components by option code.
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
s 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 10A will extend 9-3/16” (233mm) into the ductwork. The mixing tube in
FIGURE 10B 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. Options AG15 and AG17- 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, AG9, AG39, and AG41 - Slide the mixing tube into the ductwork
and attach the sensor. Connect the wires as shown on the wiring diagram.
Options AG40 and AG42 - Follow the instructions provided with the field-supplied
sensor. Refer to the wiring diagram with the unit and the field-supplied sensor to
connect the wires.
FIGURE 10A -
Discharge Air Sensor
Holder, P/N 115850,
used in Makeup Air
Option AG15 & AG17
Secure sensor in clip.
Position holder so that it
shields sensor from direct
airflow.
FIGURE 10B - A
Discharge Air Sensor
and Mixing Tube are
used in Electronic
Modulation Options
AG8, AG9, AG39, &
AG41
7.2 Supply Voltage
and Wiring
Check the rating plate on the heater for the supply voltage and current requirements.
A separate line voltage supply with fused disconnect switch should be run directly from
the main electrical panel to the furnace, making connection to leads in the junction box.