Lennox International Inc DAVE LENNOX SIGNATURE COLLECTION GAS FURNACE DOWNFLOW AIR DISCHARGE Page

TABLE 7

Maximum Allowable Intake or Exhaust Vent Length in Feet

*Size intake and exhaust pipe length separately. Values in table are for Intake OR Exhaust, not combined total. Both Intake and Exhaust must be same pipe size.

Standard Termination at Elevation 0 − 4500’

Number Of

90° Elbows

Used

	2" Pipe			2−1/2" Pipe			3" Pipe
	Model			Model			Model
070	090	110	070	090	110	070	090	110

1	91	69	14	140	93	43	162	143	118
2	86	64	9	135	88	38	157	138	113
3	81	59		130	83	33	152	133	108
4	76	54		125	78	28	147	128	103
5	71	49		120	73	23	142	123	98
6	66	44	n/a	115	68	18	137	118	93
7	61	39		110	63	13	132	113	88
8	56	34		105	58		127	108	83
9	51	29		100	53	n/a	122	103	78
10	46	24		95	48		117	98	73

Standard Termination Elevation 4501’ − 7500’

Number Of

90° Elbows

Used

	2" Pipe			2−1/2" Pipe			3" Pipe
	Model			Model			Model
070	090	110	070	090	110	070	090	110

1	66	69	14	115	93	43	137	143	118
2	61	64	9	110	88	38	132	138	113
3	56	59		105	83	33	127	133	108
4	51	54		100	78	28	122	128	103
5	46	49		95	73	23	117	123	98
6	41	44	n/a	90	68	18	112	118	93
7	36	39		85	63	13	107	113	88
8	31	34		80	58		102	108	83
9	26	29		75	53	n/a	97	103	78
10	21	24		70	48		92	98	73
			Standard Terminatiuon at Elevation 7501’ − 10,000’’
Number Of		2" Pipe			2−1/2" Pipe			3" Pipe
90° Elbows		Model			Model			Model
Used
	070	090	110	070	090	110	070	090	110
1	41	44		90	68		112	118	93
2	36	39		85	63		107	113	88
3	31	34		80	58		102	108	83
4	26	29		75	53		97	103	78
5	21	24		70	48		92	98	73
			n/a			n/a
6	16	19		65	43		87	93	68
7	11	14		60	38		82	88	63
8				55	33		77	83	58
9	n/a	n/a		50	28		72	78	53
10				45	23		67	73	48

NOTE − Table 7 continued on next page with concentric terminations.

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