Lennox MERIT ML193UH Installation Instructions Manual page 38

Nominal Internal
Iron Pipe Size Diameter
−Inches(mm) −Inches(mm)
1/2 .622
(12.7) (17.799)
3/4 .824
(19.05) (20.930)
1 1.049
(25.4) (26.645)
1−1/4 1.380
(31.75) (35.052)
1−1/2 1.610
(38.1) (40.894)
2 2.067
(50.8) (52.502)
2−1/2 2.469
(63.5) (67.713)
3 3.068
(76.2) (77.927)
4 4.026
(101.6) (102.260)
NOTE − Capacity given in cubic feet of gas per hour (kilo liters of gas per hour) and based on 0.60 specific gravity gas.
Removal of the Furnace from Common Vent
In the event that an existing furnace is removed from a
venting system commonly run with separate gas ap-
pliances, the venting system is likely to be too large to
properly vent the remaining attached appliances.
Conduct the following test while each appliance is operat-
ing and the other appliances (which are not operating) re-
main connected to the common venting system. If the
venting system has been installed improperly, you must
correct the system as indicated in the general venting re-
quirements section.
WARNING
CARBON MONOXIDE POISONING HAZARD
Failure to follow the steps outlined below for each
appliance connected to the venting system being
placed into operation could result in carbon mon-
oxide poisoning or death.
The following steps shall be followed for each ap-
pliance connected to the venting system being
placed into operation, while all other appliances
connected to the venting system are not in
operation:
1 − Seal any unused openings in the common venting sys-
tem.
2 − Inspect the venting system for proper size and horizontal
pitch. Determine that there is no blockage, restriction,
leakage, corrosion, or other deficiencies which could
cause an unsafe condition.
TABLE 10
GAS PIPE CAPACITY − FT
10 20 30
(3.048) (6.096) (9.144)
175 120 97
(4.96) (3.40) (2.75)
360 250 200
(10.19) (7.08) (5.66)
680 465 375
(19.25) (13.17) (10.62)
1400 950 770
(39.64) (26.90) (21.80)
2100 460 1180
(59.46) (41.34) (33.41)
3950 2750 2200
(111.85) (77.87) (62.30)
6300 4350 3520
(178.39) (123.17) (99.67)
11000 7700 6250
(311.48) (218.03) (176.98)
23000 15800 12800
(651.27) (447.39) (362.44)
3 /HR (kL/HR)
Length of Pipe−Feet(m)
40 50 60
(12.192) (15.240) (18.288)
82 73 66
(2.32) (2.07) (1.87)
170 151 138
(4.81) (4.28) (3.91)
320 285 260
(9.06) (8.07) (7.36)
660 580 530
(18.69) (16.42) (15.01)
990 900 810
(28.03) (25.48) (22.94)
1900 1680 1520
(53.80) (47.57) (43.04)
3000 2650 2400
(84.95) (75.04) (67.96)
5300 4750 4300
(150.07) (134.50) (121.76)
10900 9700 8800
(308.64) (274.67) (249.18)
3 − Close all building doors and windows and all doors be-
tween the space in which the appliances remaining
connected to the common venting system are located
and other spaces of the building. Turn on clothes dry-
ers and any appliances not connected to the common
venting system. Turn on any exhaust fans, such as
range hoods and bathroom exhausts, so they will oper-
ate at maximum speed. Do not operate a summer ex-
haust fan. Close fireplace dampers.
4 − Follow the lighting instructions. Turn on the appliance
that is being inspected. Adjust the thermostat so that
the appliance operates continuously.
5 − After the main burner has operated for 5 minutes, test
for leaks of flue gases at the draft hood relief opening.
Use the flame of a match or candle.
6 − After determining that each appliance connected to the
common venting system is venting properly, (step 3)
return all doors, widows, exhaust fans, fireplace damp-
ers, and any other gas−burning appliances to their pre-
vious mode of operation.
7 − If a venting problem is found during any of the preced-
ing tests, the common venting system must be modi-
fied to correct the problem.
Resize the common venting system to the minimum
vent pipe size determined by using the appropriate
tables in Appendix G. (These are in the current stan-
dards of the National Fuel Gas Code ANSI Z223.1.
Page 38
70 80 90
(21.336) (24.384) (27.432)
61 57 53
(1.73) (1.61) (1.50)
125 118 110
(3.54) (3.34) (3.11)
240 220 205
(6.80) (6.23) (5.80)
490 460 430
(13.87) (13.03) (12.18)
750 690 650
(21.24) (19.54) (18.41)
1400 1300 1220
(39.64) (36.81) (34.55)
2250 2050 1950
(63.71) (58.05) (55.22)
3900 3700 3450
(110.43) (104.77) (97.69)
8100 7500 7200
(229.36) (212.37) (203.88)
100
(30.480)
50
(1.42)
103
(2.92)
195
(5.52)
400
(11.33)
620
(17.56)
1150
(32.56)
1850
(52.38)
3250
(92.03)
6700
(189.72)