Lennox DOAS DLV User manual

1LNX15-574.2
August, 2021
INSTALLATION INSTRUCTIONS
Extended Vent Kit for Gas-Fired Furnace Options
Packaged Ventilation/Dedicated Outside Air System (DOAS)
model DLV
LNX15-574.2
5H0864980002
Application
For units with optional gas furnaces (Model Digit 17=2, 3, 5,
or 6), the standard power exhauster discharge configuration is
a horizontal exhaust cover for non-condensing (81% efficient)
furnaces and a downturn elbow for condensing (90%+ efficient)
furnaces. In certain installations, such as close proximity to
adjacent equipment or parapet walls, it is desirable to redirect
the products of combustion vertically through an extended vent
kit that terminates above the top of the unit as shown in Figure
1.1. Agency approved extended vent kits are available for field
installation as detailed on the following pages.
THIS MANUAL IS THE PROPERTY OF THE OWNER.
PLEASE BE SURE TO LEAVE IT WITH THE OWNER WHEN YOU LEAVE THE JOB.
1. The use of this manual is specifically intended
for a qualified installation and service agency.
All installation and service of these kits must be
performed by a qualified installation and service
agency.
2. These instructions must also be used in
conjunction with the Installation and Service
Manual originally shipped with the appliance, in
addition to any other accompanying component
supplier literature.
3. Modifications to the kit may result in poor
performance or nuisance alarms. Do not change
the contents of the kit or deviate from these
instructions.
IMPORTANT
Figure 1.1 – Extended Vent Kit Installed
(C-Cabinet, Non-Condensing Heat Option Shown)
CAUTION
As with any mechnical equipment, personal injury
can result from contact with sharp sheet metal
edges. Be careful when you handle this equipment.
1. Improper installation, adjustment, alteration,
service or maintenance can cause property
damage, injury or death, and could cause
exposure to substances which have been
determined by various state agencies to cause
cancer, birth defects or other reproductive harm.
Read the installation, operating and maintenance
instructions thoroughly before installing or
servicing this equipment.
2. Disconnect power supply before making wiring
connections to prevent electrical shock and
equipment damage.
WARNING

2LNX15-574.2
EXTENDED VENT KIT INSTALLATION - KIT IDENTIFICATION
EXTENDED
VENT COLLAR
GASKET
EXTENDED
VENT COLLAR
(B-VENT)
SUPPORT
BRACKETS
(2 PARTS)
TEE CAP
(B-VENT)
TEE
(B-VENT)
VENT PIPE CLAMP
SUPPORT BRACKET
VENT PIPE
(B-VENT)
LOCKING WIND
VENT CAP
(B-VENT)
ELBOW
(B-VENT)
78" VENT KITS INCLUDE AN
ADDITIONAL 90° ELBOW
Figure 2.1 – Non-Condensing Furnace Extended Vent
Kit Components 
For C-Cabinet, there are two vent assemblies and for D-Cabinet,
there are two or four vent assemblies. Refer to Table 2.2.
Table 2.2 - Extended Vent Kit Pipe Quanity by Length
Cabinet
Size
(Digit 6)
Heat Capacity and
Furnace Type
(Digit 18)
Vent Pipe Qty by
Length in Kit
36” 48” 60” 78”
B
F, G, H, J, K
(Non-Condensing) - 1 - -
R, S, T
(Condensing) 2 - - -
C
J, K, L, M
(Non-Condensing) - 1 1 -
U, V
(Condensing) 4 - - -
D
K, L, M, Q
(Non-Condensing) - - - 2
1, 2, 3, 4, 5
(Non-Condensing) - - 2 2
V, P, 6, 7, 8, 9
(Condensing and/or Hybrid) Contact Factory
Table 2.1 - Extended Vent Kit Pipe Quanity by Length
Before You Begin
Before installing the extended vent kit, verify the kit(s) to be
installed is correct for the gas heat option on the unit. To
verify, follow these steps, based on the Model DLV model
nomenclature shown on the unit serial plate:
1. Identify the Cabinet Size (Digit 6).
2. Confirm the unit has a Gas Heat Option (Digit 17=2, 3, 5,
or 6.
3. Identify the Heat Capacity (Digit 18).
4. Review Table 2.1 to determine which kit is required for the
unit to which it will be installed. The kits are marked with
Item Codes.
Example: Digit 2=C, Digit 17=2, Digit 18=M. From Table
1.1, the kit should be 40336.
5. Inspect the contents of the kit(s) to become familiarized
with the parts included. Non-condensing kit components
can be seen in Figure 2.1 and condensing kit components
can be seen in Figure 2.2. Note that kits include vent pipe
that are 36", 48", 60" or 78" in total length. Review Table
2.2 to determine how many lengths of pipe are included of
various lengths.
Example: Digit 2=C, Digit 17=2, Digit 18=M. From Table
2.2, the kits include (1) 48" pipe and (1) 60" pipe.
HOSE CLAMP
BIRD SCREEN
TERMINATION TEE
BIRD GUARD
VENT PIPES
VENT PIPE CLAMP AND
SUPPORT BRACKETS
COUPLER
EDGE SEAL
VENT ELBOW
LOCKING RING
Figure 2.2 – Condensing Furnace Extended Vent Kit
Components 
Cabinet Size
(Digit 6)
Heat Capacity and Furnace Type
(Digit 18)
Item
Code
B
F, G, H, J, K
(Non-Condensing) 40335
R, S, T
(Condensing) 40339
C
J, K, L, M
(Non-Condensing) 40336
U, V
(Condensing) 40340
D
K, L, M, Q
(Non-Condensing) 40337
1, 2, 3, 4, 5
(Non-Condensing) 40338
V, P, 6, 7, 8, 9
(Condensing and/or Hybrid)
Contact
Factory

3LNX15-574.2
Kit Installation Instructions
(For Non-Condensing Models)
4. Assemble the extended vent kit assembly (tee, tee cap,
vent pipe, vent pipe clamp support bracket, and vent cap)
as shown in Figure 3.3. Note the following:
• Do not tighten the vent extension support bracket(s)
yet. That will be tightened in a later step.
• While most B-vent components lock together when
joined, it is recommended that the joints also be
secured with the sheet metal screws provided. Drill (3)
1/8” pilot holes around the circumference of each joint
and secure with the included screws.
1. Remove the standard power exhaust vent terminal(s) from
the unit casing by removing the sheet metal mounting
screws. Refer to Figure 3.1.
2. Remove any remaining caulk that is on the casing from
removing the vent terminal(s).
3. Mount the extended vent collar(s) and collar gasket(s)
to the casing using (4) self-tapping sheet metal screws
included for each collar. The collar(s) should be centered
over the gas furnace vent outlet opening(s) so as to not
block any portion of the vent outlet opening(s). Refer to
Figure 3.2.
EXTENDED VENT KIT INSTALLATION - NON-CONDENSING
THIS SECTION APPLIES TO ONLY KITS FOR
NON-CONDENSING FURNACE OPTIONS.
REVIEW THE INFORMATION ON PAGE 2
TO CONFIRM THE PROPER KIT. IF THE KIT
TO BE INSTALLED IS FOR A CONDENSING
FURNACE, PROCEED TO PAGE 4.
REVIEW BEFORE PROCEEDING
Gas Furnace
Vent Outlet
Remove vent terminal(s).
- B-Cabinet units have one terminal
- C-Cabinet units have two terminals
- D-Cabinet units have two or four terminals
Figure 3.1
Remove Standard Power Exhaust Vent Terminal(s)
Gas Furnace
Vent Outlet
(4) Screws for each Vent Collar
- B-Cabinet units have one collar
- C-Cabinet units have two collars
- D-Cabinet units have two or four collars
Include Gasket between
Vent Collar and unit casing
Side view showing
collars centered on
outlet openings
Figure 3.2 – Extended Vent Flue Collar Installation
Installed Extended Vent Kit(s)
- B-Cabinet units have one
- C-Cabinet units have two
- D-Cabinet units have two or four
Vent Extension
Support Brackets
Figure 3.3 – Extended Vent Kit Installed
5. Place a bead of high temperature RTV caulk (by others)
around the exhaust collar where it will mate with the vent
kit tee. Fit the extended vent kit assembly to the exhaust
collar installed on the unit casing, as shown in Figure 3.3.
Verify that the vent assembly is vertically plumb. Drill (3)
1/8" diameter bite holes through the tee and into the flue
collar, equally spaced around the circumference of the tee.
Using (3) sheet metal screws provided, securely fasten the
tee to the collar.
6. Position the extended vent support bracket on the unit
casing, several inches below the bottom edge of the roof
panel. Drill (2) 1/8" diameter bite holes through the casing
panel and fasten the bracket using the sheet metal screws
provided.
7. Attach the vent pipe clamp support bracket to the extended
vent support bracket with (2) self-tapping sheet metal
screws.
8. With the brackets secured, tighten the clamp around the
vent pipe. Drill (3) 1/8" diameter bite holes through the
vent pipe and into the tee. Equally space the holes around
the circumference of the vent pipe. Using (3) sheet metal
screws, securely fasten the vent pipe to the tee.
9. Caulk the joint around the exhaust collar where it attaches
to the unit casing with high temperature RTV caulk (by
others).
10. The installation is complete.

4LNX15-574.2
4. Slide the 4” vent elbow(s) through the casing hole(s) as
shown in Figure 4.2. It will be necessary to compress the
tube slightly when inserting through the side of the unit to
get the locking tab to slip through the opening. Refer to
Figure 4.3.
1. Remove the standard 3” power exhaust discharge elbow(s)
and wall sealing grommet(s) from the unit casing. Refer to
Figure 4.1.
Kit Installation Instructions
(For Condensing Models)
EXTENDED VENT KIT INSTALLATION - CONDENSING
THIS SECTION APPLIES TO ONLY KITS FOR
CONDENSING FURNACE OPTIONS.
REVIEW THE INFORMATION ON PAGE 2 TO
CONFIRM THE PROPER KIT. IF THE KIT TO
BE INSTALLED IS FOR A NON-CONDENSING
FURNACE, GO BACK TO PAGE 3.
REVIEW BEFORE PROCEEDING
WALL SEALING
GROMMET(S)
STANDARD
DISCHARGE
ELBOW(S)
Figure 4.1
Remove Standard Power Exhaust Vent Elbow(s)
2. Install the edge seal(s) around the perimeter of the casing
opening(s) to protect the pipe(s) and help provide a partial
seal as shown in Figure 4.2.
WALL EDGE
SEAL(S)
4” DISCHARGE
ELBOW(S)
FROM KIT
3” TO 4”
COUPLER(S)
Figure 4.2 - Extended Vent Flue Collar Installation
3. On the 3” vent system that is remaining inside the unit,
install the 3” to 4” coupler(s). Tighten the coupler(s) on the
3” vent side.
Figure 4.3 - Extended Vent Elbow Locking Tab
5. Slide the locking ring over the vent pipe on the discharge
elbow(s), then slide the vent discharge elbow(s) into the
4” side of the 3” to 4” coupler(s). The discharge elbow
opening(s) should be facing up.
6. Measure the distance from the center of the opening of
the discharge elbow(s) to the casing. The measurement
should be approximately 6-5/8”. If the distance is greater
than that, remove the elbow and trim to shorten. Repeat
steps 8 thru 10 before proceeding.
7. Assemble the extended vent kit assembly as shown in
Figure 4.4. Do not tighten the vent extension support
bracket(s) yet. That will be tightened in a later step.
Installed Extended Vent Kit(s)
- B-Cabinet units have one
- C-Cabinet units have two
Vent Extension
Support Brackets
Figure 4.4 – Extended Vent Kit Installed
8. Position the extended vent support bracket on the unit
casing, several inches below the bottom edge of the roof
panel. Drill (2) 1/8" diameter bite holes through the casing
panel and fasten the bracket using the sheet metal screws
provided.

5LNX15-574.2
EXTENDED VENT KIT INSTALLATION - CONDENSING
9. Attach the vent pipe clamp support bracket to the extended
vent support bracket with (2) self-tapping sheet metal
screws.
10. With the brackets secured, tighten the clamp around the
vent pipe.
11. Caulk the joint around the edge seal(s) where the elbow(s)
pass through the unit casing with outdoor rated caulk (by
others).
12. Tighten the clamp on the 4” side of the 3” to 4” coupler.
13. Drill a 1/8” hole in the bottom of the discharge elbow(s) so
that condensate can drain out.
14. The installation is complete.

6LNX15-574.2
EXTENDED VENT KIT INSTALLATION
PAGE INTENTIONALLY LEFT BLANK

7LNX15-574.2
EXTENDED VENT KIT INSTALLATION
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8LNX15-574.2
Lennox Industries, Inc. • P.O. Box 799900 • Dallas, TX 75379-9900 • Phone: 1.800.4LENNOX (1.800.453.6669)
www.lennoxcommercial.com
© Lennox Industries, Inc. 2021
Lennox Industries, Inc. has a continuous product improvement program and
reserves the right to change design and specifications without notice.