I-RPB (04-21) 131782-A, Page 8
Bottom Duct Connections: The blower section and optional downturn plenum have duct anges for connection to
return air and supply air ducts. Duct opening sizes and curb spacing shown in FIGURE 4 is for currently manufactured
curbs that are available from the system manufacturer.
FIGURE 4 - Duct Opening Dimensions in Relation to Roof Curb Option (inches (mm))
1-5/8
(41)
1-5/8
(41)
1-5/8 (41)
1-5/8 (41)
1-5/8 (41)
1-5/8 (41)
19-1/2
(495)
19-1/2
(495)
H
H
G
Return
Duct
Supply
Duct
Roof Curb
1-5/8
(41)
1-5/8
(41)
• 1-5/8" (41mm) is the measurement from duct opening to inside edge of roof curb.
• Duct openings should be 1" larger than the duct size for installation clearance.
5.0 Mounting
(cont'd)
5.3 Mounting Base and Methods (cont'd)
5.3.3 Mounting on a Roof Curb (cont'd)
Sizes H
G
With Downturn Plenum,
Option AQ5 or AQ8
125
17-3/8" 38-5/8"
441mm 981mm
150, 175
22-7/8 38-5/8
581mm 981mm
200, 225
28-3/8 38-5/8
721mm 981mm
250, 300
36-5/8 38-5/8
930mm 981mm
350
42-1/8 38-5/8
1070mm 981mm
400
47-5/8 38-5/8
1210mm 981mm
6.0 Mechanical
WARNING
This appliance is equipped for a maximum gas supply pressure
of 1/2 psi, 3.4 kPa, or 14 inches water column. Supply pressure
higher than 1/2 psi requires installation of an additional service
regulator external to the unit.
PRESSURE TESTING SUPPLY PIPING
Test Pressures Above 1/2 PSI: Disconnect the heater and manual valve from the
gas supply line which is to be tested. Cap or plug the supply line.
Test Pressures Below 1/2 PSI: Before testing, close the manual valve on the heater.
6.1 Gas Piping and Pressures
Roof Curb Assembly and Installation Instructions (cont'd)
All piping must be in accordance with requirements outlined in the National Fuel Gas
Code NFPA54/ANSI Z223.1 (latest edition) or CSA-B149.1 (latest edition) Natural Gas
and Propane Installation Code. Gas supply piping installation should conform with
good practice and with local codes.
Corner Detail
Curb Section
Typical
Curb Detail
FIGURE 3B - Roof Curb Assembly