Lennox DT3025 User manual

Litho USA
Page 1
This appliance may be installed in an aftermarket
permanentlylocated,manufactured(mobile)home,
wherenotprohibitedbylocalcodes.Thisappliance
is only for use with the typeof gas indicated on the
rating plate. This appliance is not convertible for
use with other gases, unless a certified kit is used.
DR4035 FLUSH-FACED MODEL SHOWN

E 2001 Lennox Industries Inc.
Dallas, Texas
RETAIN THESE INSTRUCTIONS
FOR FUTURE REFERENCE
INSTALLATION
INSTRUCTIONS
DT/DTH/DR/DRH
MERITtSeries
DIRECT VENT
VENTED GAS FIREPLACE/
VENTED GAS FIREPLACE HEATER
850,010M
05/2001
Supersedes 504,023M 11/99
Table of Contents
DT/DTH/DR/DRH Unit Dimensions 2..................
Merit t Series DT/DTH/DR/DRH 2....................
Shipping and Packing List 3..........................
Requirements 3....................................
General 3.........................................
Combustion Air 4...................................
Location Selection 4................................
Installation Clearances 5............................
Framing 6.........................................
Installation 6......................................
Venting 12.........................................
Gas Piping 21......................................
Unit Start-up 21....................................
Adjustments 23.....................................
Service 24.........................................
Wiring Diagram - Millivolt Gas Valves 24...............
Wiring Diagram - Electronic Gas Valves 25.............
Repair Parts List 25.................................
Venting Kits & Available Components 26...............
WHAT TO DO IF YOU SMELL GAS:
If the information in this manual is not
followed exactly, a fire or explosion
may result causing property damage,
personal injury or loss of life.
WARNING
Do not store or use gasoline or other
flammable vapors and liquids in the
vicinity of this orany otherappliance.
Installation and service must be
performed by a qualified installer,
service agency or the gassupplier.
Do not try to light any appliance.
Do not touch any electrical switch; do not
use any phone in your building.
Immediately call your gas supplier from a
neighbor’s phone. Follow the gas supplier’s
instructions.
If you cannot reach your gas supplier, call
the fire department.
Extinguish any open flames.
FORYOURSAFETY
WH Report No. J20046561

Page 2
DT/DTH/DR/DRH Unit Dimensions - inches (mm)
A
B
C
DE
F**
G
16
(406)
1/2 (13)
1-5/8
(42)
9-3/4
(248)
3 (76)
TOP VIEW NOTE - Eyebrow
hood shown as positioned
in louvered front model.
*CONCENTRIC FLUE
FLUE - 4-1/2 (114)
COMBUSTION AIR - 7-1/2 (190)
FRAMING
SPACERS
(Top and Sides
and Rear)
GAS INLET
(Either Side
and bottom)
*DT/DTH - top flue only
DR/DRH - rear flue only
FRONT VIEW RIGHT SIDE VIEW
3 (76) 2 (51)
(Louvered Front Model Shown)
**DR/DRH - rear flue only
7 (178)
2 (51) ELECTRICAL
INLET
2-3/4x2 (70x51)
COVER PLATE with
KNOCKOUT)
Model No. A B C D E **F G
D
T/D
R
3025 in. 19-7/8 30-1/8 30-1/8 24-1/2 14 18-1/4 9-15/16
D
T/D
R
3025
DTH/DRH3025 mm 505 765 765 616 356 464 252
DT/DR3530 in. 24-7/8 35-1/8 32-1/8 29-1/2 16 20-1/4 12-7/16
D
T/D
R
3530
DTH/DRH3530 mm 632 892 816 749 406 514 316
DT/DR4035 in. 29-7/8 40-1/8 37-1/8 34-1/2 21 25-1/4 14-15/16
D
T/D
R
4035
DTH/DRH4035 mm 759 1019 943 876 533 641 379
in. 34-7/8 45-1/8 37-1/8 39-1/2 21 25-1/4 17-7/16
D
T/D
R
4540 mm 886 1146 943 1003 533 641 443
FIGURE 1
MerittSeries - DT/DTH/DR/DRH
Merit t Series fireplaces are sealed-combustion (direct
vent), heat-circulating gas appliances. The appliances
utilizea100percentsafety shut-offgascontrolwith either
a Piezo ignition system or an electronic ignition system.
Models equipped with either electronic ignition or the op-
tionalforcedair fan assembly require120Velectricalcon-
nection. Decorative trim kits, a brickaded firebox lining,
forced air fan assemblies, a wall thermostat (for use with
vented gas fireplace heater models only), and hand-held
remote ON/OFF controls are available as options. Refer
to table 1 for model designations.
Thefireplacehasprovisions forside(s)orbottomentryfor
gas piping. This appliance must be vented to the outside
andmust not be connectedtoa flueservicing anotherap-
pliance.
The appliance must be installed using only approved Lennox
concentric venting components (4-1/2 in. / 7-1/2 in.).
Themillivoltgasvalveusedinnon-electronicigni-
tion units is self-powered and does not require
120V power wiring.
Do not attempt to alter or modify the construction of the
appliance or venting components. Any modification or al-
teration of construction will void the warranty, certification
and approval of these units.
In vented gas fireplace heater models, burner operation
can be controlled by: a unit- or wall-mounted ON / OFF
switch, or an approved thermostat.
In vented gas fireplace models, burner operation can be
controlled by: a unit- or wall-mounted ON / OFF switch.
On models with the optional manually-modulated gas valve,
flame appearance and heat output can be controlled at the
gas valve. TABLE 1
Models Listed
to Vented Gas
Fireplace
Standard
Models Listed to
Vented Gas
Fireplace Heater
Standard
Suffixes Used with
Both Models
DT/DR3025
DT/DR3530
DT/DR4035
DT/DR4540
DTH/DRH3025
DTH/DRH3530
DTH/DRH4035
C - Louver front
F - Flush-Faced Front*
N-NaturalGas
P - Propane Gas (LP)
M - Millivolt System
E - Electronic system
*DRH/DTH models available with louver front only.

Page 3
Shipping and Packing List
Package 1 of 1 contains:
1 - Assembledventedfireplace/ventedfireplaceheater
(includes log set, rock wool)
1 - Envelope containing installation instructions, user’s
manual, warranty, survey card; and with the DT/DTH
models, also a vent restrictor
1 - Eyebrow
Check for shipping damage. The receiving party should con-
tact last carrier immediately if any shipping damage is found.
All venting components are ordered and shipped separately.
Requirements
Lennox Merit t Series vented gas fireplaces / vented gas
fireplace heaters are Warnock Hersey certified to ANSI
Z21.88b-1999 in USA (In Canada, CSA-2.33b-M99), and
CAN/CGA-2.17-M91 in both USA and Canada.
Installation of Lennox gas appliances must conform with lo-
cal building codes. In the absence of local codes, units must
be installed according to the current National Fuel Gas
Code (ANSI-Z223.1) in the United States. The NationalFuel
Gas Code is available from:
American National Standards Institute, Inc.
11 West 42nd Street
New York, NY 10036
In Canada, installation must conform with current Nation-
al Standard of Canada CAN/CGA-B149.1 “Installation
Code for Natural Gas Burning Appliances and Equip-
ment” and CAN/CGA-B149.2 “Installation Code for Pro-
pane Gas Burning Appliances and Equipment” and other
applicable local codes.
This appliance is Warnock Hersey certified for installation
clearances to combustible material as listed on appliance
rating plate and in table 2. Accessibility and service clear-
ances must take precedence over fire protection clear-
ances.
TABLE 2 - CLEARANCES TO COMBUSTIBLES
BACK 1/2 in. (13 mm); 0 in. (0 mm) spacers
SIDES 1/2 in. (13 mm); 0 in. (0 mm) spacers
TOP SPACERS 0 in. (0 mm)
FLOOR 0 in. (0 mm)
VENT 1 in. (25.4 mm)*
SERVICE CLEARANCES
FRONT 3 FeeT. (0.9 meters)
* 3 in. (75mm) above any horizontal vent component.
NOTE - For installation on combustible floors, appliance shall
not be installed directly on carpeting, tile, or other combus-
tible material other than wood flooring.
Fireplace must be installed so that electrical components
(if applicable) are protected from water.
When 120 volt power is installed, appliance must beelec-
trically grounded in accordance with local codes. In addi-
tion, in the United States, installation must conform with
the current National Electric Code, ANSI/NFPA No. 70.
The National Electric Code (ANSI/NFPA No. 70) is avail-
able from:
National Fire Protection Association
1BatteryMarchPark
Quincy, MA 02269
In Canada, all electrical wiring and grounding for the unit
must be according to the current regulations of the Cana-
dian Electrical Code Part I (C.S.A. Standard C22.1) and/
or local codes.
Field wiring connection with unit must meet or exceed
specifications of type T wire and withstand a maximum
temperature rise of 180
° F(82 ° C) .
These units have been Warnock Hersey certified for
installation in bedrooms and mobile homes.
General
These instructions are intended as a general guide and do
not supersede local codes in any way. Consult authorities
having jurisdiction before installation.
WARNING
Product contains fiberglass wool.
Disturbing the insulation in this product during
installation, maintenance, or repair will expose you
to fiberglass wool. Breathing this may cause lung
cancer. (Fiberglass wool is known to the State of
California to cause cancer.)
Fiberglass wool may also cause respiratory, skin,
and eye irritation.
To reduce exposure tothis substance or forfurther
information, consult material safety data sheets
available from address shown below, or contact
your supervisor.
Lennox Industries Inc.
P.O. Box 799900
Dallas, TX 75379-9900 USA
1 - This appliance is certified for use with the factory-sup-
plied glass panel only. Do not operate the appliance if
the glass is broken or cracked or if the glass has been
removed. Striking the glass panel may result in glass
breakage. Replacement glass panel must be ordered
from Lennox and should only be installed by a qualified
service technician.
2 - All parts removed for servicing should be replaced be-
fore operating the appliance.
3 - Solid fuel must not be used with this appliance.
4 - Surface temperatures on the appliance are very high.
Make sure that both children and adults are aware of
the danger of burns or clothing ignition.

Page 4
5 - Warn the homeowner against leaving young children
unsupervised in the room with the appliance.
6 - Due to high temperatures, locate the appliance out of
traffic and away from furniture and draperies.
7 - Instruct the homeowner not to leave damp or wet
clothingorother flammable materialtodryon or near
the appliance.
8 - Keep the appliance area clear and free of combustible
materials, gasoline and other flammable vapors and
liquids.
9 - On initial start-up, operate the appliancecontinuous-
ly for 10 to12 hours on the high flame setting. During
this period, make sure that the room is well venti-
lated. This “break-in” procedure is required to burn
off the odors associated with a new fireplace.
Combustion Air
These Lennox Merit t Series vented gas fireplaces / vented
gas fireplace heaters have been designed to use 100 per-
cent air from outdoors for combustion.
WARNING
Do not install appliance in a corrosive or contaminated
atmosphere. Meet all combustion and ventilation air
requirements, as well as all local codes.
Location Selection
Install the fireplace out of direct sunlight to maximize the
unit’s visible glow effect. Also, consider the following
when selecting a location for the Lennox vented gas fire-
place / vented gas fireplace heater :
1 - Allrequirementsindicatedinventingsection mustbe
met. This includes restrictions on horizontal and ver-
tical vent lengths and vent termination locations.
2 - Centerappliancebetweentwowallstuds,ifpossible,
to simplify venting.
3 - If optional blower is used, consider power wiring re-
quirements.
4 - Air circulation patterns should be unobstructed.
5 - See figure 2 for typical appliance applications.
6 - Do not install appliance directly on carpeting.
7 - If fireplace is to be installed on tile or other combus-
tible material other than wood flooring, it must be
installed on a metal or wood panel extending the full
width and depth of the base.
8 - Provideaminimum3ft.(.9m)clearanceinfrontofthe
appliance for service and proper operation.
TYPICAL APPLIANCE APPLICATIONS
VERTICAL VENT
(Top Vent
Application)
*INSTALLATION WITH ONE SIDE OF UNIT
FLUSH WITH A WALL (Opposite wall must
not extend beyond front of fireplace.)
*RECESSED INSTALLATION
(Side walls must not extend
beyond front edges of
fireplace.)
TOP VENT
APPLICATION
TOP VENT
APPLICATION
REAR VENT
APPLICATION
HORIZONTAL VENT
(Rear Vent Application
With a chase)
HORIZONTAL VENT
(Rear Vent Application
without a chase)
HORIZONTAL VENT
(Top Vent
Application)
VERTICAL VENT
(Rear Vent
Application)
REAR VENT
APPLICATION
TOP VENT APPLICATION
TOP VENT
APPLICATION
*Note - The side walls of mantels may protrude
beyond the front face of the fireplace a maximum
of 5 inches (127mm). See figure 3 for mantel
clearances above the fireplace.
Note - DT/DTH models have only a top flue outlet .
DR/DRH models have only a rear flue outlet.
FIGURE 2

Page 5
Installation Clearances
Clearances to Combustibles
TheLennoxMerit
t Seriesvented fireplaces/ventedfire-
place heaters are approved with zero clearance to com-
bustible materials on all sides (as detailed in table 2), with
the following exception: When the unit is installed with
one side flush with a wall, the wall on the other side of the
unit must not extend beyond the front edge of the unit. In
addition, when the unit is recessed, the side walls sur-
rounding the unit must not extend beyond the front edge
of the unit. See figure 2.
Mantel Clearances
Vertical installation clearances to combustible mantels
varyaccordingtothe depthofthemantel.Figure3 details
these required clearances. Mantels constructed of non-
combustible materials may be installed at any height
above the appliance opening; however, do not allow any-
thing to hang below the eyebrow.
NOTE - Paintor lacquer used tofinish the mantel mustbe
heat resistant in order to avoid discoloration.
12 (305) MANTEL
10 (254) MANTEL
8 (203) MANTEL
6 (152) MANTEL
4 (102) MANTEL
4
(102)
14
(356) 12
(305) 10
(254) 2 (51) MANTEL TOP OF
APPLIANCE
6
(152)
NOTE - Eyebrow shown as positioned
in louvered front model. The eyebrow
position in the flush faced front model
is lower than shown.
8
(203)
MANTEL CLEARANCES
Inches (mm)
FIGURE 3
Corner Installations
Units installed across the corner of two joining walls re-
quire a minimum diagonal span as detailed in figure 4.
This span accommodates the unit depth.
A
B
CD
E
Back wall of chase/enclosure
(including any finishing materials)
DT/DTH
DR/DRH
a
7in.
(178 mm)
RECTANGULAR
TERMINATION
NOTE -
Venting requirements for DR/DRH Units (Rear Vent Units)
in corner installations -
- The rectangular termination must be used.
- For the 3025, 3530, and 4035 models, the horizontal vent
length “a” to “b,” must not exceed 28 in. (711mm).
b
F
CORNER INSTALLATIONS
Top (DT/DTH) or Rear (DR/DRH) Vent Application
Model No. A B C D E F
in. 30-1/8 57-1/2 40-5/8 13-1/2 28-3/4 5
DT/DTH/DR/DRH 3025 mm 765 1461 1032 343 730 127
in. 35-1/8 57-1/2 40-5/8 13-1/2 28-3/4 5
DT/DTH/DR/DRH 3530 mm 892 1461 1032 343 730 127
in. 40-1/8 61-3/16 43-11/32 15-7/16 30-11/16 6-3/8
DT/DTH/DR/DRH 4035 mm 1019 1554 1101 392 779 162
FIGURE 4

Page 6
Framing
Wood or metal framing must accommodate unit outer
shell as shown in figure 5. If unit is to be elevated above
floor level, a solid platform providing continuous support
(e.g. plywood decking) must be constructed.
A
BD
FRAMING
DT/DTH VENT FRAMING -
TOP VENT WITH ONE
90
_ ELBOW
DR/DRH VENT FRAMING -
REAR VENT WITH
NO ELBOWS
Framing should be constructed of
2x4 or larger lumber.
7
(178)
5-1/8
(130) 12-1/8
(308)
7
(178)
5-1/8
(130)
10-1/2
(267)
Inches (mm)
15-7/8
(403)
C
12-1/8
(308)
Model No. A B C D
DR/ in. 30-1/4 33-1/4 18-1/4 ----
DRH
3025 mm 768 845 464 ----
DR/ in. 35-1/4 35-1/4 20-1/4 ----
DRH
3530 mm 895 895 514 ----
DR/ in. 40-1/4 40-1/4 25-1/4 ----
DRH
4035 mm 1022 1022 641 ----
DR in. 45-1/4 40-1/4 25-1/4 ---- DR
4540 mm 1149 1022 641 ----
DT/ in. 30-1/4 33-1/4 ---- 38-1/4
DTH
3025 mm 768 845 ---- 972
DT/ in. 35-1/4 35-1/4 ---- 40-1/4
DTH
3530 mm 895 895 ---- 1022
DT/ in. 40-1/4 40-1/4 ---- 45-1/4
DTH
4035 mm 1022 1022 ---- 1149
DT in. 45-1/4 40-1/4 ---- 45-1/4 DT
4540 mm 1149 1022 ---- 1149
FIGURE 5
Installation
Installation should be performed by a qualified technician
according to these instructions and local codes.
1 - Carefully remove assembled vented fireplace /
vented fireplace heater from packaging and place in
desired location.
WARNING
Combustible materials may be installed flush with
both sides and top front edges of the fireplace.
Combustible materials must NEVER overlap the
edges onto the front face of the appliance. Joints
between the finished wall and the fireplace edges
can only be sealed with a 300
_ F (149 _ C) minimum
sealant.
Non-combustible materials can be used to cover
the gap between the combustible wall materials
and the fireplace. On flush-faced models, non-
combustible materials may coverthe upper portion
of the top panel down to, but not beyond the top of,
the eyebrow. You must not modify the air inlet or
outlet grills in any way. Access to panels must not
be obstructed.
2 - Lift and remove the bustle; in flush-faced model
applications, remove the top panel; in louvered-
face model applications, remove the louvers.
3 - Lower the bottom hinged panel. Remove three se-
curing screws at the bottom ofthe glass panel. Care-
fully lift and remove the shrink-wrapped glass panel/
log set assembly. Lay the assembly down, and cut
and remove the shrink-wrapping.
4 - Position the logs as shown in figure 6 (3025 units),
figure 7 (3530 units), figure 8 (4035 units), or figure
9 (4540 units). Handle logs carefully, to prevent
breakage. The logs are notched to accommodate
the burner tube, pilot assembly and each other.
5 - Place rock wool (ember material) as shown in figure 10.
NOTE-Yourapplicationmaynotrequiretheuseofall
of the provided rock wool. Reserve remaining rock
wool for replacement, if necessary.
6 - Remove cardboard from pressure relief valves lo-
cated on top of the firebox.
7 - Secureappliancetofloorusingfold-downtabsonthe
sides of the fireplace. Additional holes for securing
screwsarealsoprovidedinthebaseoftheunitunder
the firebox.

Page 7
DT/DTH/DR/DRH 3025 LOG PLACEMENT
Log Stamping
Part Number
Log
Number
1
195
2
196
3 197
4 198
Lennox
Part Number
Lennox Part Number
for entire log set: 18L76
19L60
19L61
19L62
19L63
4
2
1
3
2
3
4
1
FIGURE 6

Page 8
DT/DTH/DR/DRH 3530 LOG PLACEMENT
Log Stamping
Part Number
Log
Number
1
199
2
1910
3 1911
4 1912
2
34
1
Lennox
Part Number
Lennox Part Number
for entire log set: 18L77
19L64
19L65
21L10
21L11
4
2
1
3
FIGURE 7

Page 9
DT/DTH/DR/DRH 4035 LOG PLACEMENT
Log Stamping
Part Number
Log
Number
1 1919
2 1918
3 1920
4
1923
Lennox
Part Number
Lennox Part Number
for entire log set: 18L78
19L67
19L66
19L68
19L69
5
6
1921 19L70
1922 19L71
2
34
1
5 6
4
2
1
36
5
FIGURE 8

Page 10
DT/DTH/DR/DRH 4540 LOG PLACEMENT
Log Stamping
Part Number
Log
Number
1
1924
2
1925
3 1920
4
1922
Lennox
Part Number
19L72
19L73
19L68
19L71
5
61923 19L69
1921 19L70
1926 19L74
7
4
2
1
36
5
7
2
3
1
5
4
6
7
Lennox Part Number
for entire log set: 18L79
FIGURE 9

Page 11
PLACEMENT OF EMBER MATERIAL ON FRONT BURNER
SEPARATE ROCK WOOL INTO PIECES ABOUT THE SIZE OF A NICKEL. KEEP THE PIECES FLUFFED UP, NOT MATTED,
AND PLACE APPROXIMATELY AS SHOWN IN THIS FIGURE.
NOTE - TOO MANY EMBERS ON THE FRONT BURNER WILL CAUSE POOR COMBUSTION.
FIGURE 10
8- Millivolt Wiring (Millivolt Units) -
In applications where the burner switch is to be unit-
mounted in the field -
Install the switch in the gas valve mounted bracket
and wire according to figure 37.
In applications where the burner switch is to be wall-
mounted -
Install a field-provided handy box in a convenient
location adjacent to the appliance. Install the ON/OFF
switch and faceplate and wire according to figure 37.
In thermostat applications -
Install the thermostat in a suitable location and wire
accordingtofigure37.
9- 24 Volt Wiring (Electronic Ignition Units) -
In applications where the burner switch is to be unit-
mounted in the field -
Install the ON/OFF switch in the gas valve mounted
bracket and wire according to figure 38.
In applications where the burner switch is to be wall-
mounted -
Install a field-provided handy box in a convenient
location adjacent to the appliance. Install ON/OFF
switch and faceplate and wire according to figure 38.
In thermostat applications -
Install the thermostat in a suitable location and wire
accordingtofigurefigure38.
10 - 120 Volt Wiring -
MillivoltUnits- 120voltwiringisrequiredonMillivolt
units only when a fan kit is being installed. Wire fan
kitaccordingtofigure37.
ElectronicIgnitionUnitsAllelectronicignitionunits
require120voltwiring.Installwiring according tofig-
ure 38.
When 120 volt electrical power is applied, the ap-
pliance must be electrically grounded according to
localcodes or, intheabsenceoflocal codes, withthe
current National Electric Code, ANSI/NFPA No. 70,
in the USA or CSA C22.1 Canadian Electrical Code
in Canada.
11 - Prepare the vent collar for use as indicated in the
venting section. Attach either Lennox flexible or unit-
ized rigid concentric vent to vent collar, at the top
(DT/DTH units) or rear (DR/DRH units), of the ap-
pliance as indicated in the venting section. Vent ter-
minations are indicated in venting section.
12 - Makegas pipingconnections asindicated in gaspip-
ing section.
WARNING
Do not operate appliance unless glass frame is
properly installed. Glass must not be broken or
cracked. If glass is damaged, replace with ap-
propriate glass/frameassembly availablethrough
Lennoxrepairparts.Substitutionofanyotherthan
Lennox-specified glass can lead to property dam-
age or personal injury.
13 - Carefully reinstall the glass door. Tighten the three
bolts at the bottom of the door securely.
14- Install the bustle; in flush-faced model applica-
tions,installthetoppanel;inlouvered-facemodel
applications, install the louvers.
15 -Remove the eyebrow from its protective wrap-
ping.Slidetheeyebrow intothe slotson the lower
edges of the radiant panel(flush-faced model ap-
plications) or the lower edges of the cabinet top
(louvered-face model applications).
NOTE - The eyebrow must be used in all applications.
16 - Continue with the procedures indicated in the start-up
and adjustments section.

Page 12
Venting
General Requirements
These instructions should be used as a guideline and do
notsupersede localcodes in anyway.Installventaccord-
ingto localcodes, theseinstructions, the currentNational
Fuel Gas Code (ANSI-Z223.1) in the USA or the current
standards of CAN/CGA-B149.1 and -B149.2 in Canada.
This gas fireplace is equipped with a concentric vent col-
lar for ease of installation. The concentric vent pipe will
bring in outdoor air for combustion and will remove ex-
haust gases. Vent terminations are ordered separately.
This Lennox gas fireplace is for use only with Lennox
approved concentric vent pipe: rigid vent pipe in vertical
venting applications, and rigid or flexible vent pipe in
horizontal applications. Each vent must be terminated
using a Lennox vent termination. Approved venting kits
and components are listed on page 26 of this manual.
NOTE - The vent terminations are certified for use
with this unit and must be installed without modifica-
tion.
WARNING
All vent system connections/joints must be properly
sealed using only Lennox MILL-PAC BLACK HIGH
TEMPERATURE SEALANT, Catalog Number 10K81.
Failure to properly seal the vent system could allow
carbon monoxide leakage resulting in injury or death.
Sealing and Joining Rigid Vent Pipe
Apply only Lennox MILL-PAC BLACK HIGH TEM-
PERATURE SEALANT (Catalog number 10K81)
around outside of inner and outer vent collars before
assembling vent to collar. Outer pipe must also be se-
cured to outer collar using three sheet metal screws.
See figure 11. Sealant must be applied toall rigid pipe
joints and the outer pipe must be secured with three
sheet metal screws.
SECURING RIGID VENT PIPE TO COLLAR
USE THREE SCREWS TO
SECURE OUTER VENT
PIPE TO OUTER COLLAR
APPLY ONLY LENNOX MILL-PAC BLACK HIGH
TEMPERATURE SEALANT (Catalog No. 10K81)
AND SLIDE RIGID PIPE OVER INNER AND
OUTER COLLARS.
NOTE - The bottom part of
the outer pipe is omitted in
order to show the detail of
the inner pipe.
RIGID VENT
PIPE
FIGURE 11
Sealing and Connecting Flexible Vent Pipe
Flexible vent pipe is packaged and shipped in its con-
tracted state. When installing flexible vent pipe, its length
may be expanded to twice its contracted size. You should
expecttoextenda3ft.sectionofflexiblepipeupto6ft.
IMPORTANT
Under no circumstances, may separate sections of
concentric flexible vent pipe be joined together.
When flexible vent pipe is used, both inner and outer
pipes should be secured to the fireplace concentric
collar and to the vent termination using only Lennox
MILL-PACBLACKHIGHTEMPERATURESEALANT
(Catalog number 10K81) and metal gear clamps as
shown in figure 12.
SECURING VENT PIPE TO COLLAR
FLEXVENT
OUTER
COLLAR
GEAR
CLAMPS
HOLES PROVIDE
SCREWDRIVER ACCESS
FOR TIGHTENING INNER
GEAR CLAMP.
APPLY ONLY LENNOX MILL-PAC
BLACK HIGH TEMPERATURE
SEALANT (Catalog No. 10K81)
AND SLIDE FLEXIBLE PIPE OVER
INNER AND OUTER COLLARS.
NOTE - Part of the outer
pipe is pulled away to show
the detail of the inner pipe.
FIGURE 12

Page 13
Vertical Venting Through the Roof
This Lennox gas fireplace is for use only with Lennox
approved concentric vent pipe; only rigid vent pipe may
be used when vertically venting the fireplace through
the roof.
DT/DTH Applications - See figures 16, 17, or 18 for vent
length requirements using concentric vent pipe.
DR/DRHApplications-Seefigures19,20,or21 forvent
length requirements using concentric vent pipe.
DT/DTH and DR/DRH Applications -
Figure15providesadetailoftheverticalventtermination.
Figure 22 shows the minimum vent termination height re-
quirements above a flat or sloped roof.
General guidelines for vertical vent installations:
1- DT/DTH Models -
Install a vent restrictor (provided) in the flue outlet as
shown in figure 13.
VENT RESTRICTOR INSTALLATION
WHEN USING THE TOP FLUE OUTLET IN VERTICAL VENTING
APPLICATIONS, INSTALL RESTRICTOR FLUSH WITH FLUE
COLLAR OUTLET.
SIDE VIEW
FLUSH
RESTRICTOR
INNER
COLLAR
CABINET TOP
(DT/DTH UNITS ONLY)
COLLAR
OUTER
RESTRICTOR
TOPFLUEOUTLET
FIGURE 13
1 - Provide a firestop / spacer any time vent pipe must
pass through a combustible floor, ceiling or wall. See
figure14.Referto listingonpage26 for catalognum-
bers of Lennox firestop spacers.
2- Horizontal sections of the vent pipe run should
beslopedupwardaminimumof1/4in.perfoot of
horizontal vent in the direction away from the
fireplace. In addition, horizontal sections of pipe
must be supported using metal straps spaced
every 2 ft.
3 - Maintain proper clearances any time vent pipe must
passthroughinsulated spaces.Use insulationshield
when vent pipe passes through any insulation.
4- Two45
_ elbows may be used in place of one 90 _ el-
bow. This can only occur once in the entire venting
system.
One45
_ elbowmay besubstitutedforone90 _ elbow
at any point in the venting system.
The same rise to run ratios as shown in the venting
figures must be followed if 45
_ elbows are used.
FIRESTOP / SPACER
(Vertical Applications Shown)
NOTE - Horizontal ap-
plications require 3 inch
(76mm) clearance above
top of vent.
FIGURE 14
VERTICAL TERMINATION DETAIL
LENNOX MILL-PAC
BLACK HIGH
TEMPERATURE
SEALANT
(Catalog Number 10K81)
RIGID VENT
FIGURE 15

Page 14
DT/DTH VERTICAL VENTING FIGURES
VERTICAL VENTING WITHOUT ELBOWS
(DT/DTH - Top Vent Units)
V
V = 40 feet
Maximum
Install flashing and storm
collar at the point the vent pipe
passes through the roof.
Firestop/Spacer must be used any time
vent pipe passes through combustible
floor or ceiling or wall.
FIGURE 16
VERTICAL VENTING USING TWO 90 _ ELBOWS
(DT/DTH - Top Vent Units)
V1 H
1ft.min. 3ft.max.
2ft.min. 6ft.max.
3ft.min. 9ft.max.
4 ft. min. 12 ft. max.
5 ft. min. 15 ft. max.
17 ft. max.6ft.min.
H
V1
V2
V1 + V2 = 40 ft. Maximum.
H = 17 ft. Maximum.
Firestop/Spacer must be used any
time vent pipe passes through
combustible floor or ceiling or wall.
FIGURE 17
VERTICAL VENTING USING THREE 90
_ ELBOWS
(DT/DTH - Top Vent Units)
V1 H1 + H2
1ft.min. 3ft.max.
2ft.min. 6ft.max.
3ft.min. 9ft.max.
4 ft. min. 12 ft. max.
5 ft. min. 15 ft. max.
6 ft. min. 17 ft. max. V1
H2
H1
V2
V1 + V2 = 40 ft. Maximum.
H1 + H2 = 17 ft. Maximum.
Firestop/Spacer must be used any
time vent pipe passes through
combustible floor or ceiling or wall.
FIGURE 18

Page 15
DR/DRH VERTICAL VENTING FIGURES
VERTICAL VENTING USING ONE 90 _ ELBOW
(DR/DRH - Rear Vent Units)
VH
1ft.min. 2ft.max.
2ft.min. 4ft.max.
3ft.min. 6ft.max.
4ft.min. 8ft.max.
V
H
V+H = 40 ft. MAX.
H = 8 ft. MAX.
Firestop/Spacer must be used any
time vent pipe passes through
combustible floor or ceiling or wall.
FIGURE 19
VERTICAL VENTING USING TWO 90 _ ELBOWS
(DR/DRH - Rear Vent Units)
VH1+H2
1ft.min. 2ft.max.
2ft.min. 4ft.max.
3ft.min. 6ft.max.
4ft.min. 8ft.max.
40 ft. max. 8 ft. max.
H2
H1
V
Firestop/Spacer must be used any
time vent pipe passes through
combustible floor or ceiling or wall.
FIGURE 20
VERTICAL VENTING USING THREE 90 _ ELBOWS
(DR/DRH - Rear Vent Units)
V1 H1
2ft.min. 4ft.max.
3ft.min. 6ft.max.
4ft.min. 8ft.max.
5ft.min. 8ft.max.
6ft.min. 8ft.max.
H1 + H2
6ft.max.
9ft.max.
12 ft. max.
15 ft. max.
17 ft. max.
1ft.min. 2ft.max. 3ft.max.
V1 + V2 =40 ft. Maximum.
H1 = 8 ft. Maximum
H1 + H2 = 17 ft. Maximum.
H2
V1
V2
H1
Firestop/Spacer must be used any
time vent pipe passes through
combustible floor or ceiling or wall.
FIGURE 21

Page 16
1.0
1.25
1.5
2.0
2.5
3.25
4.0
5.0
6.0
7.0
7.5
8.0
FLAT TO 6/12
6/12 TO 7/12
7/12 TO 8/12
8/12 TO 9/12
9/12 TO 10/12
10/12 TO 11/12
11/12 TO 12/12
12/12 TO 14/12
14/12 TO 16/12
16/12 TO 18/12
18/12 TO 20 /12
20/12 TO 21/12
2FTMIN.
2FTMIN.
Lowest
Discharge
Opening
H*
*H = MINIMUM HEIGHT FROM ROOF
TO LOWEST DISCHARGE OPENING
OF VENT
12
X
Roof Pitch is X/12
TERMINATION HEIGHTS FOR VENTS ABOVE
FLAT OR SLOPED ROOFS
Horizontal Overhang
Vertical
Wall
ROOF PITCH H-FT
Vent
Termination
Storm Collar
Concentric Vent Pipe
Flashing
FIGURE 22
Detailed steps for installation of the vertical vent at
and above the roof:
1 - Determine the location of the vent’s penetration of
the roof.
2 - Covertheopeningsoftheconcentricventandcutthe
hole in the roof large enough in order to provide a
minimum of one inch (25.4mm) clearance to roof
combustible material.
3 - Frame the vent hole (with material of at least the
same dimensions as the roof rafters) in order to pro-
vide adequate nailing support for the roof-to-vent
flashing. (Note - Vent assembly above the roof may
be subjected to high winds).
4 - Install the remaining vent sections and the vent ter-
mination. See figure 22 for minimum allowable ter-
mination heights above the roof and minimum allow-
able clearances to obstacles above the roof.
5 - Use both flashing and a storm collar at the point
where the vent pipe exits the roof. Seal flashing to
roof, and storm collar to vent with non-hardening
caulking compound.
Horizontal Venting Through a Side Wall
This Lennox gas fireplace is for use only with Lennox
approved concentric vent pipe; either rigid or flexible
vent pipe may be used when horizontally venting the
fireplace through a side wall.
DT/DTH Applications - See figures 23, 24, or 25 for vent
length requirements using concentric vent pipe.
DR/DRHApplications-Seefigures26,27,or28 forvent
length requirements using concentric vent pipe.
Also, see figure 4 for venting in a corner installation.
General guidelines for horizontal vent installations:
1 - Provide a firestop / spacer any time vent pipe must
pass through a combustible floor, ceiling or wall. See
figure14.Referto listingonpage26 forcatalognum-
bers of Lennox firestop spacers.
2- Horizontal sections of the vent pipe run should be
sloped upward a minimum of 1/4 in. per foot of hori-
zontal vent in the direction away from the fireplace.
In addition, horizontal sections of pipe must be sup-
ported using metal straps spaced every 2 ft.
3 - Maintain proper clearances any time vent pipe must
passthroughinsulated spaces.Use insulationshield
when vent pipe passes through any insulation.
4- Two45
_ elbows may be used in place of one 90 _ el-
bow. This can only occur once in the entire venting
system.
One45
_ elbowmay besubstitutedforone90 _ elbow
at any point in the venting system.
The same rise to run ratios as shown in the venting
figures must be followed if 45
_ elbows are used.
5 - The longest length of flexible vent pipe available is 48
inches, measured when in its compressed form. Flex-
ible vent pipe may not be applicable in every venting
configuration depicted in figures 23, 24, 25, 27, and
28, depending on the total vent length required.
IMPORTANT
Under no circumstances, may separate sections of
concentric flexible vent pipe be joined together.

Page 17
DT/DTH HORIZONTAL VENTING FIGURES
HORIZONTAL VENTING USING ONE 90 _ ELBOW
(DT/DTH - Top Vent Units)
VH
*1 ft. min. 3ft.max.
2ft.min. 4ft.max.
3ft.min. 6ft.max.
4ft.min. 8ft.max.
5 ft. min. 17 ft. max.
20 ft. max. 17 ft. max.
V
H
Firestop/Spacer must be used any
time vent pipe passes through
combustible floor or ceiling or wall.
**NOTE: THE LONGEST LENGTH OF FLEX AVAILABLE
IS 48 INCHES OF COMPRESSED FLEX.
* 10-1/2 in. min. for flexible vent pipe.
RIGID VENT PIPE SHOWN; **FLEXIBLE VENT
PIPE MAY ALSO BE USED.
Rectangular termination shown;
round termination may also be used.
FIGURE 23
HORIZONTAL VENTING USING TWO 90 _ ELBOWS
(DT/DTH - Top Vent Units)
V1
*1 ft. min.
2ft.min.
3ft.min.
4ft.min.
5ft.min.
H1 + H2
3ft.max.
6ft.max.
9ft.max.
12 ft. max.
15 ft. max.
V1
H1
H2
6ft.min. 17 ft. max.
20 ft. max. 17 ft. max.
Firestop/Spacer must be used any
time vent pipe passes through
combustible floor or ceiling or wall.
RIGID VENT PIPE SHOWN; **FLEXIBLE VENT
PIPE MAY ALSO BE USED.
* 10-1/2 in. min. for flexible vent pipe.
**NOTE: THE LONGEST LENGTH OF FLEX AVAILABLE
IS 48 INCHES OF COMPRESSED FLEX.
Rectangular termination shown;
round termination may also be used.
FIGURE 24
HORIZONTAL VENTING USING THREE 90 _ ELBOWS
(DT/DTH - Top Vent Units)
V1 + V2
2ft.min.
3ft.min.
4ft.min.
5ft.min.
6ft.min.
H1 + H2
4ft.max.
6ft.max.
8ft.max.
15 ft. max.
17 ft. max.
V1
H1
H2
V2
20 ft. max. 17 ft. max.
Firestop/Spacer must be used any
time vent pipe passes through
combustible floor or ceiling or wall.
RIGID VENT PIPE SHOWN; *FLEXIBLE VENT
PIPE MAY ALSO BE USED.
*NOTE: THE LONGEST LENGTH OF FLEX AVAILABLE
IS 48 INCHES OF COMPRESSED FLEX.
Rectangular termination shown;
round termination may also be used.
FIGURE 25

Page 18
DR/DRH HORIZONTAL VENTING FIGURES
HORIZONTAL VENTING WITHOUT ELBOWS
(DR/DRH - Rear Vent Units)
**H
ONLY THE RECTANGULAR TERMINATION MAY BE USED.
Firestop/Spacer must be used any
time vent pipe passes through
combustible floor or ceiling or wall.
RIGID VENT PIPE SHOWN; FLEXIBLE VENT PIPE
MAYALSOBEUSED.
7in.
**For 4540 models
H = 18 in. (457 mm) Maximum.
**For 3025, 3530, and 4035 models
H = 28 in. (711 mm) Maximum.
FIGURE 26
HORIZONTAL VENTING USING TWO 90 _ ELBOWS
(DR/DRH - Rear Vent Units)
VH1
2ft.min. 4ft.max.
3ft.min. 6ft.max.
4ft.min. 8ft.max.
5ft.min. 8ft.max.
6ft.min. 8ft.max.
H1 + H2
6ft.max.
9ft.max.
12 ft. max.
15 ft. max.
17 ft. max.
1ft.min. 2ft.max. 3ft.max.
H2
V
H1
20 ft. max. 8 ft. max. 17 ft. max.
Firestop/Spacer must be used any
time vent pipe passes through
combustible floor or ceiling or wall.
RIGID VENT PIPE SHOWN; *FLEXIBLE VENT
PIPE MAY ALSO BE USED.
*NOTE: THE LONGEST LENGTH OF FLEX AVAILABLE
IS 48 INCHES OF COMPRESSED FLEX.
Rectangular termination shown;
round termination may also be used.
FIGURE 27
HORIZONTAL VENTING USING THREE 90 _ ELBOWS
(DR/DRH - Rear Vent Units)
VH1
2ft.min. 4ft.max.
3ft.min. 6ft.max.
4ft.min. 8ft.max.
5ft.min. 8ft.max.
20 ft. max. 8 ft. max.
H1 + H2 + H3
6ft.max.
9ft.max.
12 ft. max.
15 ft. max.
17 ft. max.
V
H3
H2
H1
1ft.min. 2ft.max. 3ft.max.
6 ft. min. 8 ft. max. 17 ft. max. Firestop/Spacer must be used any
time vent pipe passes through
combustible floor or ceiling or wall.
RIGID VENT PIPE SHOWN; *FLEXIBLE VENT
PIPE MAY ALSO BE USED.
Rectangular termination shown;
round termination may also be used.
*NOTE: THE LONGEST LENGTH OF FLEX AVAILABLE
IS 48 INCHES OF COMPRESSED FLEX.
FIGURE 28

Page 19
Horizontal Vent Terminations
In the United States, refer to local codes, ANSI Z223.1, and
the vent clearances chart indicated infigure 31for horizontal
vent termination requirements. In Canada, refer to local
codes, CAN / CGA B149.1 or .2, and the vent clearances
chart indicated in figure 31.
Both round (figure 29) and rectangular (figure 30)
vent terminations are available for use in horizontal
applications. However, the rectangular termination
detailed in figure 30 is the only one approved for use
inapplicationswithoutelbowsasdetailedinfigure26
or in corner installations as shown in figure 4.
ROUND HORIZONTAL VENT TERMINATION
1 in. (25mm) SPACER INTEGRAL TO VENT
TERMINATION AT BOTTOM AND SIDES
OUTSIDE
WALL SURFACE
3 in. (76mm) SPACER INTEGRAL
TO VENT TERMINATION AT TOP
3 in. (76mm)
1in.
(25mm)
FIRESTOP / SPACER
AT INSIDE WALL SURFACE
FACEPLATE INTEGRAL
TO VENT TERMINATION
VENT TERMINATION
The termination faceplate shall not be recessed into a
wall or siding.
Note -
FIGURE 29
Therectangular ventterminationmay beinstalleddirectly
on the fireplace vent collar. The termination can be ad-
justed to accommodate wall thicknesses from 5 in.
(127mm) to 9 in. (229mm). In applications with wall thick-
nessesrangingfrom9in.(229mm)to13in.(330mm),use
extension JVEXT4 (Catalog Number 12L01) between
fireplace vent collar and termination.
RECTANGULAR VENT TERMINATION
(Shown with rigid vent pipe)
7
(178)
5-1/8
(130)
10-1/2
(267)
12-1/8
(308)
CENTER OF VENT
TERMINATION
BASE
(See Note 2)
HORIZONTAL VENT
FIRESTOP / SPACER
(See Note 1)
FRAMING
INCHES (mm)
1 - The firestop/spacer may be installed on either side
of the vent framing (interior or exterior side).
HEAT DEFLECTOR
Notes -
2 - The termination base shall not be recessed into a
wall or siding.
FIGURE 30

Page 20
EXTERIOR HORIZONTAL VENT TERMINATION CLEARANCES
A - Clearance above grade, veranda, porch, deck, or balcony
-- *12 in. (305mm) minimum.
B - Clearance to openable window or door -- *12 in. (305mm)
minimum.
C - Clearance to permanently closed window -- minimum 9 in.
(228mm)intheUnitedStatesand12in.(305mm)inCanada
recommended to prevent condensation on window.
D - Vertical clearance to ventilated soffit located above the ter-
minalwithinahorizontaldistanceof18in.(457mm)fromthe
center line of the terminal -- 18 in. (457mm) minimum.
E - Clearance to unventilated soffit -- 12 in. (305mm) minimum.
F - Clearance to outside corner -- 5 in. (127mm) minimum.
G - Clearance to inside corner -- 6 in. (152mm) minimum).
H - *Nottobeinstalledaboveameter/regulatorassemblywith-
in3ft.(.9m)horizontallyfromthecenterlineoftheregulator.
I - Clearance to service regulator vent outlet -- 3 ft. (915mm)
in the United States and *6 ft. (1.8m) in Canada minimum.
J - Clearance to non-mechanical air supply inlet to building or
the combustion air inlet to any other appliance -- 9 in.
(228mm)intheUnitedStatesand*12in.(305mm)inCana-
da minimum.
K - Clearance to mechanical air supply inlet -- 3 ft. (915mm) in
the United States and *6 ft. (1.8m) in Canada minimum.
L - †Clearance above paved sidewalk or a paved driveway lo-
cated on public property -- *7 ft. (2.1m) minimum.
M - ‡Clearanceunderveranda,porch,deck,orbalcony--12in.
(305mm) minimum.
N - Vent termination must not be located in a recessed area.
†A vent shall not terminate directly above a sidewalk or paved driveway which is located between two
single family dwellings and serves both dwellings.*
‡Only permitted if veranda, porch, deck, or balcony is fully open on a minimum of two sides beneath
the floor.*
*As specified in CAN/CGA B149 Installation Codes.
NOTE - Local codes or regulations may require different clearances.
FIGURE 31