Duct Sizes - Greenheck IGX Series Installation, Operation And Maintenance Manual

See charts for duct sizes and straight duct lengths recommended for optimal performance based on AMCA
Publication 201-90. Using duct sizes less than recommended will affect fan performance. Follow good duct
installation practices for the remaining ductwork.
Furnace Size
Housing
(MBH)
100
150
12
200
250
150
200
250
300
22
350
400
500
600
250
300
350
400
500
32
600
700
800
1050
1200
6 Model IGX Make-Up Air
Installation

Duct Sizes

Down Discharge
H W
25 23
25 23
25 23
25 23
26 25
26 25
26 25
26 25
26 34
26 34
26 25
26 25
26 34
26 34
26 34
26 34
26 34
26 34
26 34
26 34
26 34
26 34
End Discharge
H W
15 31
21 31
27 31
32 31
21 31
27 31
32 31
38 31
39 41.4
39 41.4
32 31
38 31
30 41
30 41
39 41
39 41
30 41
30 41
39 41
39 41
39 41
39 41
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