Lennox SL280UHNV Installation Instructions Manual page 16

14 - All venting pipe passing through floors, walls, and
ceilings must be installed with the listed clearance
to combustible materials and be fire stopped
according to local codes. In absence of local codes,
refer to NFGC (Z223.1).
15 - No portion of the venting system can extend into,
or pass through any circulation air duct or plenum.
16 - Vent connectors serving Category I appliances shall
not be connected to any portion of mechanical draft
systems operating under positive pressure such as
Category III or IV venting systems
17 - If vent connectors are combined prior to entering
the common vent, the maximum common vent
capacity listed in the common venting tables must
be reduced by 10%, the equivalent of one 90° elbow
(0.90 x maximum common vent capacity).
Capacity of Type B Double-Wall Vents with Type B Double-Wall Connectors
Height Lateral
H L
(feet) (feet)
0
2
6
4
6
0
2
8
5
8
0
2
10
5
10
0
2
15 5
10
15
0
2
5
20
10
15
20
0
2
5
30 10
15
20
30
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 maximum listed capacity).
Serving a Single Category I Appliance
Vent and Connector Diameter - D (inches)
3 inch
Appliance Input Rating in Thousands of Btu Per Hour
Min Max Min
0 78
13 51
21 49
25 46
0 84
12 57
23 53
28 49
0 88
12 61
23 57
30 51
0 94
11 69
22 65
29 59
35 53
0 97
10 75
21 71
28 64
34 58
48 52
0 100
9 81
21 77
27 70
33 64
56 58
NA NA
18 - The common vent diameter must always be at least
as large as the largest vent connector diameter.
19 - In no case, shall the vent connector be sized more
than two consecutive table size diameters over the
size of the draft hood outlet or flue collar outlet.
20 - Do not install a manual damper, barometric draft
regulator or flue restrictor between the furnace and
the chimney.
21 - When connecting this appliance to an existing
dedicated or common venting system, you must
inspect the venting system's general condition
and look for signs of corrosion. The existing vent
pipe size must conform to these instructions and
the provided venting tables. If the existing venting
system does not meet these requirements, it must
be reized.
TABLE 3
4 inch
Max Min
0 152
18 97 27
30 94 39
36 91 47
0 165
16 109 25
32 103 42
39 98 51
0 175
17 118 23
32 113 41
41 104 54
0 191
15 136 20
30 130 39
40 121 51
48 112 61
0 202
14 149 18
29 143 38
38 133 50
46 124 59
55 116 69
0 213
13 166 14
28 160 36
37 150 48
44 141 57
53 132 66
73 113 88
Page 16
5 inch
Max Min
0 251
157 32
153 50
149 59
0 276
178 28
171 53
164 64
0 295
194 26
187 52
176 67
0 327
226 22
219 49
206 64
195 76
0 349
250 20
242 47
229 62
217 73
206 84
0 374
283 18
275 45
262 59
249 70
237 80
214 104
6 inch
Max
0 375
232
227
223
0 415
263
255
247
0 447
289
280
267
0 502
339
330
315
301
0 540
377
367
351
337
322
0 587
432
421
405
389
374
346