Reznor RPB Unit Installation Manual - Manual (Page 21)

Form I-RPB, P/N 131782 R12, Page 21
• Duct Sizing - Proper sizing of the supply air ductwork is necessary to ensure a
satisfactory heating installation. The recognized authority for such information is
the Air Conditioning Contractors Association, 2800 Shirlington Road, Suite 300,
Arlington, VA 22206 (www.acca.org). A manual covering duct sizing in detail may
be purchased directly from them.
Furnace
Duct
“U” Channel
of Light
Gauge Metal
FIGURE 23B
- Install "U"
Channel on
Sides of Duct
Connection
Heater Duct
Access Panel
in Duct
6” (152mm)
10” (254mm)
1
2
3
“U” Channel
(See FIGURE 9.)
FIGURE 23A - Connecting Supply Air Duct to the Furnace
(1) Flanges on the furnace (heat exchanger) turn out as shown. (2) Shape duct connection as shown - "U" on top
and bottom; "L" on sides. (3) Slide "U" channels over furnace top and bottom flanges making connection.
Form "U" channels to seal sides. Drill and lock with sheetmetal screws.
CAUTION: Joints where supply air ducts attach to the furnace must be sealed securely to prevent
air leakage into drafthood or burner rack area. Leakage can cause poor combustion, pilot problems,
shorten heat exchanger life and cause poor performance. See Hazard levels, page 2.
•
Bottom Duct/Furnace Connections - On outdoor models, insert ducts from
below roof deck through roof opening into the heater. Form 1" (25mm) flanges, fold
over, and fasten with sheetmetal screws inside heater. Gain access to the unit by
removing side panels from the blower and downturn plenum sections. Ducts must
be attached and sealed to provide airtight connections.
• Return Air Duct/Furnace Connection - All return air ducts should be attached
and sealed to return air flanges to provide airtight connection.
• Return Air Duct/Grill Size - Make certain that return air ducting or grills have a
free area equal to the return duct size connection.
CAUTION: An external duct system static pressure not within the limits shown on the rating plate,
or improper motor pulley or belt adjustment, may overload the motor. See Hazard Levels, page 2.
• Removable Panels - The ducts should have removable access panels on
both upstream and downstream sides of the furnace. These openings must be
accessible when the furnace is in service and should be a minimum of 6" x 10"
in size so smoke or reflected light may be observed inside the casing to indicate
the presence of leaks in the heat exchanger. The covers for the openings must be
attached in such a manner as to prevent leakage. See FIGURE 23A.
• Supply Air Duct/Furnace Horizontal Connection - The seal between the furnace
and the duct must be mechanical. Duct connection should be made with "U" type
flanges on the top and bottom of the connecting duct. Slide the duct over the
flanges of the heater giving an airtight fit. Provide "U" type channels for the other
side flanges to ensure tight joints. Use sheetmetal screws to fasten ducts and "U"
channels to the furnace flange. See FIGURES 23A and 23B.
6.4.2 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 8.1.3).
Makeup air Options AG15, AG8, AG9, AG39, and AG40 require field installation of the
sensor in the discharge ductwork. Option AG15 uses the box and sensor holder in
FIGURE 23A. Options AG8, AG9, and AG39 include a sensor and mixing tube like the
one illustrated in FIGURE 23B. Option AG40 requires a field-supplied sensor.
Follow the instructions below to install the sensor in the ductwork.
For control information, see Paragraph 8.1.