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The maximum recommended chimney height in all
applications which include the vent adapter is 35 feet
(10.6m).
Vent connector from the vent adapter to the tile−lined
chimney must be constructed of type B, double−wall vent
pipe.
The furnace vent connector rise shall not exceed 3 feet
(.9m).
Vent connector lateral length must not exceed 18"
(457mm) for each inch of vent connector diameter. For
example, a 6" (152mm) diameter vent connector would
have a maximum lateral length of 9 feet (2.7m).
Vent connectors should not be sized more than two sizes
greater than the listed appliance categorized vent
diameter, flue collar diameter, or drafthood outlet
diameter.
The vent sizing tables allow for two 90° turns. For each
additional turn, or equivalent, reduce the maximum
capacity listed in the venting tables by 10 percent (.90 X
maximum table capacity).
Interpolation is permitted when calculating capacities for
vent dimensions that fall between table entries; however,
extrapolation beyond the table entries is not permitted.
Size the chimney and vent connector per table 3 and
figure 2 when a single appliance is being vented into an
interior masonry chimney. Size the chimney and vent
connector per tables 4 and 5 and figure 3 when using an
interior or exterior masonry chimney as a common vent
serving multiple appliances.
Use table 6 to determine the equivalent area of masonry
chimney liners.
TABLE 3
Interior Masonry Chimney Only
Type B Double Wall Vent Connector Serving a Single 80AF1UH, ML180UH, EL280UH or SL280UH Furnace
with Masonry Chimney Vent Adapter Kit
Vent
Height
H
(ft)
Lateral
L
(ft)
Type B Double Wall Vent Connector Diameter − (inches)
to be used with chimney areas within the size limits at bottom
6 in.
7 in.
8 in.
Appliance Input Rate in Thousands of Btu per Hour
NAT
Max
NAT
Max
NAT
Max
6
2
5
130
117
180
165
247
231
8
2
5
8
145
134
127
198
183
175
266
247
239
10
2
5
8
162
148
139
221
204
191
298
277
263
15
2
5
10
12
179
164
153
148
250
231
216
210
336
313
296
290
20
2
5
10
12
210
184
172
167
274
254
237
230
375
350
332
325
30
2
5
10
12
216
198
184
179
303
281
263
255
421
393
373
365
35
2
5
10
12
225
206
192
186
315
291
273
265
435
406
386
378
MASONRY CHIMNEY INTERNAL AREA
Minimum internal area of chimney (in.
2
)
38
50
63
Maximum internal area of chimney (in.
2
)
198
269
352
