Lennox International Inc Merit Series Gas Furnace installation instructions Feet

TABLE 4

Capacity of Type B Double−Wall Vents with Single−Wall Metal Connectors

Serving a Single Category I Appliance

					Vent and Connector Diameter − D (inches)
Height	Lateral
			3 Inch			4 Inch			5 Inch			6 Inch
H	L
					Appliance Input Rating in Thousands of Btu Per Hour
(feet)	(feet)
		MIN		MAX	MIN		MAX	MIN		MAX	MIN		MAX
	0	38		77	59		151	85		249	126		373
	2	39		51	60		96	85		156	123		231
6
	4	NA		NA	74		92	102		152	146		225
	6	NA		NA	83		89	114		147	163		220
	0	37		83	58		164	83		273	123		412
	2	39		56	59		108	83		176	121		261
8
	5	NA		NA	77		102	107		168	151		252
	8	NA		NA	90		95	122		161	175		243
	0	37		87	57		174	82		293	120		444
	2	39		61	59		117	82		193	119		287
10
	5	52		56	76		111	105		185	148		277
	10	NA		NA	97		100	132		171	188		261
	0	36		93	56		190	80		325	116		499
	2	38		69	57		136	80		225	115		337
15	5	51		63	75		128	102		216	144		326
	10	NA		NA	95		116	128		201	182		308
	15	NA		NA	NA		NA	158		186	220		290
	0	35		96	54		200	78		346	114		537
	2	37		74	56		148	78		248	113		375
	5	50		68	73		140	100		239	141		363
20
	10	NA		NA	93		129	125		223	177		344
	15	NA		NA	NA		NA	155		208	216		325
	20	NA		NA	NA		NA	186		192	254		306
	0	34		99	53		211	76		372	110		584
	2	37		80	55		164	76		281	109		429
	5	49		74	72		157	98		271	136		417
30	10	NA		NA	91		144	122		255	171		397
	15	NA		NA	115		131	151		239	208		377
	20	NA		NA	NA		NA	181		223	246		357
	30	NA		NA	NA		NA	NA		NA	NA		NA

NOTE − Single appliance venting configurations with zero lateral lengths are assumed to have no elbows in the vent system. For all other vent configurations, the vent system is assumed to have two 90° elbows. For each additional 90° elbow or equivalent (for example two 45° elbows equal one 90° elbow) beyond two, the maximum capacity listed in the venting table should be reduced by 10 percent (0.90 x maxi- mum listed capacity).

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