Lennox 18M7901 User manual

03/12
*2P0312*
506774−01
*P506774-01*
INSTALLATION INSTRUCTIONS FOR MASONRY CHIMNEY VENT ADAPTER KIT
(18M7901) USED WITH 80AF1UH, ML180UH, EL280UH and SL280UH UNITS
Litho U.S.A.
506774−01
03/2012
Supersedes 03/2011
2012
Dallas, Texas MASONRY CHIMNEY
VENT ADAPTER
GAS UNITS
KITS & ACCESSORIES
Shipping and Packing List
Package 1 of 1 contains:
1 − Vent adapter assembly
1 − Template
Application
The masonry chimney vent adapter kit allows venting of
80 percent efficient furnaces into a tile−lined masonry
chimney without the use of a listed metal lining system.
The vent adapter assembly introduces dilution air into the
flue gases, thus lowering the dew point of the gases and
inhibiting the production of condensation.
This vent adapter is designed for use with 80AF1UH,
ML180UH, EL280UH and SL280UH units installed in
upflow air discharge applications. The kit may be used
with furnaces fueled by either natural gas or LP/propane
gas. Refer to table 1 for a complete listing of the furnaces
with which this adapter kit may be used.
This kit has been CSA International certified for use with
80AF1UH, ML180UH, EL280UH and SL280UH
furnaces when installed in accordance with these
instructions.
The furnace must be installed in accordance with all
national and local building codes or, in the absence of
local codes, with the National Fuel Gas Code NFPA
54/ANSI Z223.1 (latest edition) and other applicable
codes. In Canada, installation must be in accordance
with the National Canadian Installation Code CAN/CGA
B149.1 OR B149.2 (latest edition) and other applicable
codes.
This vent adapter kit has been designed and tested for
use with 80AF1UH, ML180UH, EL280UH and SL280UH
units installed in masonry chimney vent applications in
accordance with limitations set by NFPA 54 and the
International Mechanical Code. The included vent
tables and guidelines must be followed exactly to
ensure proper vent and unit operation and to
minimize chimney wet time.
Table 1 also lists the minimum allowable winter design
temperatures for each model when used with the vent
adapter. The map in figure 1 provides winter design
temperatures for the contiguous United States. Portions
of this document are reprinted with permission from NFPA
54: National Fuel Gas Code 1999, National Fire
Protection Association, Quincy, MA 02269. This reprinted
material is not the complete and official position of the
National Fire Protection Association on the referenced
subject, which is represented only by the standard in its
entirety.
TABLE 1
Minimum Winter Design Temperatures for Use with
80AF1UH, ML180UH, EL280UH and SL280UH
Furnaces with Vent Adapter Kit in Both Interior and
Exterior Masonry Chimney Applications
Minimum Winter Design Temperature* °F (°C)
All Models
All Input Sizes
Interior Chimney −10° F (−23° C)
Exterior Chimney +5° F (−15° C)
*Refer to 99% Minimum Winter Design Temperature table
provided in the current edition of the ASHRAE Fundamentals
Handbook.
Installation Checklist
Verify furnace model numbers approved for use
with kit (table 1).
Verify that winter design temperature is appropri-
ate for application of kit (table 1 and figure 1).
Verify condition of chimney.
Measure chimney height and inside area of lined
chimney.
Verify chimney and vent connector size (tables 3,
4 and 5).
Install vent adapter kit (page 6).
Connect blocked vent switch wiring (figure 5, page
7).
Test blocked vent switch.
Test for proper draft and check for spillage (page
8).
Place furnace into operation (page 8).

Page 2
FIGURE 1
−10oF
−10oF
5oF
17oF
27oF
37oF
37oF
27oF
17oF
5oF
−10oF
99% Winter Design Temperatures for the Contiguous United States
This map is a necessarily generalized guide to temperatures in the contiguous Unites States. Temperatures shown for areas such as
mountainous regions and large urban centers may not be accurate. The data used to develop this map was taken from the 1993 ASHRAE
Fundamentals Handbook (Chapter 24, Table 1: Climate Conditions for the United States.
This map has been reprinted with permission from NFPA 54: National Fuel Gas Code 1999, National Fire Protection Association, Quincy,
MA 02269. This reprinted material is not the complete and official position of the National Fire Protection Association on the referenced subject,
which is represented only by the standard in its entirety.
Table 2 lists winter design temperatures for some of the
major U. S. cities.
TABLE 2
Minimum Winter Design Temperatures
of Major U. S. Cities
City Minimum Winter Design
Temperature −− °F (°C)
Baltimore +10°F (−12°C)
Boston +6°F (−14°C)
Chicago −8°F (−22°C)
Columbus, OH 0°F (−18°C)
Des Moines −10°F (−23°C)
Detroit +3°F (−16°C)
Kansas City +2°F (−17°C)
New York +11°F (−12°C)
Philadelphia +10°F (−12°C)
Pittsburgh +1°F (−17°C)
Salt Lake City +3°F (−16°C)
St. Louis +2°F (−17°C)
Requirements
The room temperature surrounding the furnace and vent
connectors must be at least 60°F (16°C).
The space surrounding the furnace must not be
depressurized by more than 0.2" w.c. below the outdoor
pressure (caused by exhaust fans, clothes dryers, etc.)
Furnace capacity must not exceed 1.7 times the
calculated heating load.
Sea level input ratings should be used when determining
maximum capacity for high altitude installation.
If the furnace is to be vented into an exterior chimney, the
furnace must share a common vent with at least one
drafthood−equipped appliance to prevent condensation in
the masonry chimney.
If the furnace is to be vented into an interior chimney, the
furnace may be vented as a single appliance or into a
shared vent.
Chimney and Vent Connector
Requirements and Sizing
The masonry chimney vent adapter kit may only be used
in applications which include vent exit through the
furnace top cap. Applications which require side vent
exit are not permissible.
When two or more appliances are vented into a single
masonry chimney, the flow area of the largest section of
vertical vent shall not exceed seven times the flow area
of the vent adapter outlet or drafthood outlet , whichever
is smaller, unless the vent is designed in accordance
with approved engineering methods.

Page 3
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
62
5
130
117
180
165
247
231
82
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

Page 4
FIGURE 2
Type B Double Wall Vent Connector with Interior Tile−Lined Masonry
Chimney Serving a Single 80AF1UH, ML180UH, EL280UH or
SL280UH Furnace Equipped with Vent Adapter Kit
Type B Double Wall Vent Connector with Interior or Exterior Tile−Lined Masonry
Chimney Serving a Single 80AF1UH, ML180UH, EL280UH or SL280UH Furnace
Equipped with Vent Adapter Kit and One or More Drafthood−Equipped Appliances
(Typical Application Shown)
FIGURE 3
TILE−LINED
MASONRY
CHIMNEY
PERMANENTLY
SEALED FIREPLACE
OPENING
FURNACE
B VENT
VENT
ADAPTER
ASSEMBLY
TILE−LINED
MASONRY
CHIMNEY
PERMANENTLY
SEALED FIREPLACE
OPENING
FURNACE
OTHER
APPLIANCE
B VENT
VENT
ADAPTER
ASSEMBLY
L
H
R
R = VENT
CONNECTOR
RISE
H

Page 5
TABLE 4
Multiple Appliance for Interior and Exterior Masonry Chimney
Type B Double Wall Vent Connectors Serving a Single 80AF1UH, ML180UH, EL280UH or SL280UH Furnace
with Masonry Chimney Vent Adapter Kit and One or More Drafthood−Equipped Appliances
Vent
Height
H
(ft)
Connector
Rise
R
(ft)
Type B Double Wall Connector Diameter − (inches)
6 in. 7 in. 8 in.
Appliance Input Rate in Thousands of Btu per Hour
NAT
Max
NAT
Max
NAT
Max
6
1
2
3
101
124
143
141
173
203
201
232
270
8
1
2
3
105
127
145
148
179
206
210
240
276
10
1
2
3
108
129
148
153
184
209
216
247
281
15
1
2
3
114
134
153
164
192
215
229
260
292
20
1
2
3
119
138
157
173
199
222
239
270
301
30
1
2
3
127
145
163
187
209
233
255
287
317
35
1
2
3
131
149
167
194
216
240
265
297
332
TABLE 5
Multiple Appliance for Interior and Exterior Masonry Chimney
MASONRY CHIMNEY INTERNAL AREA
Height
H
(ft)
Minimum Internal Area of Chimney (Square Inches)
38 50 63
Combined Appliance Input Rating in Thousands of Btu Per Hour
NAT
+NAT
NAT
+NAT
NAT
+NAT
6 103 143 188
8119 163 218
10 131 177 236
15 152 212 283
20 172 243 325
30 198 278 381
35 NR 291 401
NR − Not recommended for vent configuration.

Page 6
TABLE 6
Equivalent Area of Masonry Chimney Liners
Nominal Liner Size
(inches X inches)
Inside Liner
Dimensions
(inches)
Inside Diameter or
Equivalent Diameter
(inches)
Equivalent Area
(square inches)
4 X 8 2−1/2 X 6−1/2
4 12.2
5 19.6
6 28.3
7 38.3
8 X 8 6−3/4 X 6−3/4 7.4 42.7
8 50.3
8 X12 6−1/2 X 10−1/2 9 63.6
10 78.5
12 X12 9−3/4 X 9−3/4 10.4 83.3
11 95
12 X 16 9−1/2 X 13−1/2
11.8 107.5
12 113
14 153.9
16 X 16 13−1/4 X 13−1/4 14.5 162.9
15 176.7
16 X 20 13 X 17 16.2 206.1
18 254.4
20 X 20 16−1/2 X 16−3/4 18.2 260.2
20 314.1
Inspection of Tile−Lined Masonry Chimney
The chimney must be inspected and found to be in good
condition. Chimney construction must conform with the
National Fuel Gas Code NFPA 54/ANSI Z223.1, Standard
for Chimneys, Fireplaces, Vents and Solid−Fuel−Burning
Appliances ANSI/NFPA 211, and to any applicable state
or local codes.
The following conditions must be confirmed before
continuing with installation of the vent system:
Chimney must be lined with clay tile.
Chimney crown must be in good condition. Missing
mortar or brick must be replaced.
Tile liner and top seal must be in good condition. If
necessary, make repairs.
All debris (mortar, tile, fuel oil residue, etc.) must be
removed from chimney clean out.
Tile liner must be inspected to make sure that tiles
are properly aligned, that all sections are complete
and that there are no gaps. If necessary, make
repairs.
Exterior chimneys must serve at least one other
drafthood−equipped appliance. Verify before
continuing.
Chimney must be properly sized per these
instructions.
Installation
1 − Turn off all gas supply and electrical power to unit.
WARNING
These instructions must be followed exactly. This
kit must be installed by a qualified service techni-
cian. Improper installation may result in personal
injury, loss of life, equipment damage, or damage to
the existing masonry chimney.
2 − A 7/8" diameter hole is required to accommodate
the conduit for the wiring from the blocked vent
switch in the vent adapter to the pressure switch in
the furnace. A template is provided to ensure proper
location of the hole in the unit top cap.
The conduit hole must be positioned carefully to
avoid contact between the blocked vent switch
wiring and the combustion air inducer or hot
surfaces inside the furnace.

Page 7
The 7/8" diameter hole for the electrical conduit can
be located in three different locations in the top cap
depending upon which furnace model that the vent
adapter is being applied. The three locations are
labeled A, B, and C on the Vent Adapter Kit Conduit
Placement Template included with the kit.
Location A is for EL280UH and SL280UH models
with the following gas inputs: 070, 110, 135 and
SL280UH090V60C
NOTE − 80AF1UH and ML180UH models cannot
use location A or the flange on the upper access
door will interfere with the electrical conduit on
the vent adapter.
Location B is for 80AF1UH, ML180UH models with
the following gas inputs: 045, 070, 110 and 135.
Location C is for 80AF1UH and ML180UH with 090
gas inputs and EL280UH and SL280UH models that
are in B−size cabinets: EL280UH090P36B,
EL280UH090P48B, SL280UH090V36B and
SL280UH090V48B (see figure 4)
NOTE − The louvers in the top cap on B−size
cabinets will interfere with the electrical conduit
on vent adapter if locations A and B are used.
Make sure there is clearance to evaporator coil.
3 − Position the vent adapter assembly on the furnace
flue transition as shown in figure 4 (location C).
FIGURE 4
TYPE B
DOUBLE−WALLED
VENT PIPE
VENT ADAPTER
ASSEMBLY
CONDUIT
VENT ADAPTER ASSEMBLY INSTALLATION
(B−Size Cabinet Shown)
4 − Remove the locknut from the vent adapter assembly
conduit. Route the two wires through the 7/8" hole in the
furnace top cap. Use the locknut to secure the conduit
to the furnace top cap.
5 − Use three field−provided, self−drilling sheet metal
screws to firmly secure the vent adapter assembly to
the round collar of the unit flue transition. Drive one
self−drilling screw through the front and one through
each side of the vent adapter assembly and collar.
WARNING
Asphyxiation hazard. The vent adapter assembly
must be securely attached to the furnace flue tran-
sition and the vent pipe at all times.
6 − The vent adapter assembly includes a blocked vent
switch which must be wired into the furnace
combustion air proving pressure switch as shown in
figure 5. This manually reset switch interrupts unit
operation when the vent is blocked. The switch must
not be reset until vent blockage is cleared.
a − Remove one of the purple wires from the
combustion air proving pressure switch.
Connect this wire to the switch wire with the male
1/4" quick connect terminal.
b − Connect the switch wire with the female 1/4"
quick connect terminal to the open contact on the
combustion air proving pressure switch.
FIELD WIRING
FIGURE 5
VENT ADAPTER
ASSEMBLY
(with blocked vent
switch)
WIRE WITH 1/4"
FEMALE QUICK
CONNECT
TERMINAL
PURPLE WIRE
PURPLE WIRE
DISCONNECT
FROM PRESSURE
SWITCH
WIRE WITH 1/4"
MALE QUICK
CONNECT
TERMINAL
PRESSURE SWITCH
(Low pressure switch on
SL280UH models)
7 − Use three field−provided self−drilling screws to secure
the double−walled B−vent to the top of the vent adapter
assembly. Drive one self−drilling screw through the
front and one through each side. Route the vent to the
masonry chimney using the shortest possible route.
If an elbow is required to route the vent connector to
the chimney, it must be installed at least 1 ft. above the
furnace vent outlet. A 2 ft. clearance before the first
elbow is preferable. See figure 6.

Page 8
Common Venting Using Tile−Lined Masonry Chimney
TILE−LINED
MASONRY
CHIMNEY
PERMANENTLY
SEALED FIREPLACE
OPENING
FURNACE
OTHER
APPLIANCE
FIGURE 6
B VENT
VENT
ADAPTER
ASSEMBLY
1 FOOT
MINIMUM
(2 ft.
preferred)
8 − When an exterior masonry chimney is being used,
the furnace must be commonly vented with at least
one other drafthood−equipped gas−fired appliance.
9 − Continue with furnace installation, start−up and
adjustments as outlined in furnace installation
instructions.
NOTE − Furnace blower heating speed should be
adjusted so that temperature rise is at the high
end of the range listed on the unit rating plate.
10 − Test the operation of the blocked vent switch.
CAUTION − Ensure good ventilation of the area
where the furnace is installed before performing
this test.
a − Remove double−walled B−vent from top of vent
adapter assembly.
b − Adjust room thermostat to signal heating
demand.
c − Allow furnace to operate for 2 minutes, then
completely cover the top of the vent adapter
assembly outlet to simulate a vent blockage.
Furnace should shut off within 2 minutes.
d − Remove blockage and allow unit to cool for 5
minutes. Press reset button on blocked vent
switch. Reinstall double−walled vent pipe. Adjust
thermostat to normal setting.
11 − Test the furnace for proper draft and spillage.
a − 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.
b − Close all building doors and windows and all
doors between the space in which the
appliances remaining connected to the common
venting system are located and other spaces of
the building. Turn on clothes dryers 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 operate at maximum speed. Do not operate
a summer exhaust fan. Close fireplace dampers.
c − Follow the lighting instructions. Turn on the
appliance that is being inspected. Adjust the
thermostat so that the appliance operates
continuously.
d − After the main burner has operated for 5
minutes, test for leaks of flue gases at the draft
hood or vent adapter relief opening. Use the
flame of a match or candle, or smoke from a
cigarette, cigar, or pipe.
e − After determining that each appliance
connected to the common venting system is
venting properly, (step 3) return all doors,
windows, exhaust fans, fireplace dampers, and
any other gas−burning appliances to their
previous mode of operation.
f − If a venting problem is found during any of the
preceding tests, the common venting system
must be modified to correct the problem.
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