Lennox International Inc G61MP Series Units Minimum Vent Pipe Lengths, Maximum Vent Pipe Lengths

Use the following steps to correctly size vent pipe diameter. Refer to Vent Pipe Size Determination Worksheet on page 53.

1 − Determine the vent termination and its corresponding equivalent feet value according to table 5.

2 − Determine the number of 90° elbows required for both indoor and outdoor (e.g. snow riser) use. Calculate the corresponding equivalent feet of vent pipe.

3 − Determine the number of 45° elbows required for both indoor and outdoor use. Calculate the corresponding equivalent feet of vent pipe.

4 − Determine the length of straight pipe required.

5 − Add the total equivalent feet calculated in steps 1 through 4 and compare that length to the maximum values given in table 6 for the proposed vent pipe di- ameter. If the total equivalent length required exceeds the maximum equivalent length listed in the appropri- ate table, evaluate the next larger size pipe.

TABLE 6

MINIMUM VENT PIPE LENGTHS

G61MP	MIN. EQUIV.	EXAMPLE
MODEL	VENT LENGTH
045, 070,		5 ft. plus 2 elbows of 2", 2−1/2", 3"
071, 090,
		or 4" diameter pipe
091
110, 111**	15 ft.*	5 ft. plus 2 elbows of 2−1/2" 3" or 4"
		diameter pipe
135***		5 ft. plus 2 elbows of 3" or 4"
		diameter pipe

*Any approved termination may be added to the minimum equivalent length listed.

**G61MP−48C−110, G61MP−60C−110 and G61MP−60C−111 must have 90° street ell (supplied or field replacment Canadian kit) installed directly into unit flue collar.

***G61MP−60D−135 must have 3" to 2" reducing ell (supplied or field replac- ment Canadian ki) installed directly into unit flue collar.

TABLE 7

MAXIMUM VENT PIPE LENGTHS

		MAXIMUM EQUIVALENT VENT
ALTITUDE	G61MP		LENGTH FEET
	MODEL	2"	2−1/2"	3"	4"
		PIPE	PIPE	PIPE	PIPE
	045	59	65	77	234
	070	59	65	78	214
	071†	59	65	78	214
0 − 4500	090	26	42	72	204
(0 − 1371 m)	091†	26	42	72	204
	110*	n/a	32	72	179
	111*†	n/a	32	72	179
	135**‡	n/a	n/a	61	160
	045	59	65	77	234
	070	59	65	78	214
	071†	59	65	78	214
4501−7500	090	26	42	72	204
(1372−2286 m)	091†	26	42	72	204
	110*	n/a	32	72	179
	111*†	n/a	32	72	179
	135**‡	n/a	n/a	46	160
	045	59	65	77	234
	070	59	65	78	214
	071†	59	65	78	214
7501 − 10000	090	26	42	72	204
(2287 − 3048 m)	091†	26	42	72	204
	110*	n/a	32	72	179
	111*†	n/a	32	72	179
	135**‡	n/a	n/a	46	160

n/a −− Not allowed.

*G61MP−48C−110, G61MP−60C−110 and G61MP−60C−111must have 90° street ell (supplied or field replacment Canadian ki) installed directly into unit flue collar.

**G61MP−60D−135 must have 3" to 2" reducing ell (supplied or field replacment Canadian ki) installed directly into unit flue collar.

***90° elbows used in configuration of G61MP−60D−135 vent, must be lim- ited to 3" sweep elbows.

†On G61MP−071, −091 and −111 units, sweep elbows must be used for all 90° elbows in the venting system when 2", 2−1/2" or 3" vent pipe is used. Sweep elbows are recommended for use in vent systems of other G61MP units.

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