Lennox LF24 User manual

E N G I N E E R I N G D A T A
G A S U N I T H E A T E R S / D U C T F U R N A C E S
LF24
UNIT HEATERS
Horizontal − 60 HZ
Bulletin No. 210000
July 2007
Supersedes June 2007
Steady State Efficiency − up to 80.5%
Input − 100,000 to 400,000 Btuh
Front View Back View
Tubular Heat Exchanger
MODEL NUMBER IDENTIFICATION
Nominal Gas Heat Input
100 = 100,000 Btuh
115 = 115,000 Btuh
145 = 145,000 Btuh
175 = 175,000 Btuh
200 = 200,000 Btuh
230 = 230,000 Btuh
250 = 250,000 Btuh
300 = 300,000 Btuh
345 = 345,000 Btuh
400 = 390,000 Btuh
A24
Series
LF
Unit Type
LF − Lennox Unit Heater
Heat Exchanger Type
A = Aluminized Steel Heat Exchanger
S = Stainless Steel Heat Exchanger
200−
FEATURES
CONTENTS
Dimensions Pages 4−5. . . . . . . . . . . . . . . . . . . . . . . . . . .
Features Pages 1−2. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Guide Specifications Pages 8−11. . . . . . . . . . . . . . . . . .
High Altitude Information Page 5. . . . . . . . . . . . . . . . . .
Installation Clearances Page 5. . . . . . . . . . . . . . . . . . . .
Model Number Identification Page 1. . . . . . . . . . . . . . .
Mounting Height Page 5. . . . . . . . . . . . . . . . . . . . . . . . . .
Optional Accessories Page 3−4. . . . . . . . . . . . . . . . . . .
Specifications Page 3−4. . . . . . . . . . . . . . . . . . . . . . . . . .
Throw Data Page 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maximum Horizontal Vent Lengths Page 5. . . . . . . . . .
EQUIPMENT Warranty
Heat exchanger − stainless steel − fifteen year limited
warranty, aluminized steel − ten year limited warranty.
All other covered components − one year limited warranty.
Refer to Lennox Equipment Limited Warranty certificate
included with equipment for details.

LF24 − 100,000 to 400,000 Btuh / Page 2
FEATURES
Applications
Lennox LF24 gas−fired, horizontal unit heaters are
compact in design and easy to install.
Units feature steady−state heating efficiencies of up to
80.5%.
LF24 unit heaters are ideal for economical commercial
heating systems.
Units are shipped completely assembled with controls
factory installed and wired.
In addition, each unit is test operated at the factory to
ensure proper operation and dependability.
Installer has only to locate unit, make unit gas supply, flue,
electrical connections and mount thermostat to complete
the installation.
Units may be vented horizontally or vertically.
Approvals
Units certified by CSA International.
Listed by the California Energy Commission (CEC).
Units are certified for natural or LPG/Propane gas.
ISO 9001 Registered Manufacturing Quality System.
HEATING SYSTEM
24 volt redundant combination gas control valve
combines a manual main shutoff valve, pressure
regulation and automatic electric valve (dual) into one
compact combination control.
Solid−state electronic direct spark ignition control provides
positive and safe main burner ignition.
Spark is intermittent and occurs only when required.
Separate electronic flame sensor control assures safe
and reliable operation.
Should loss of flame occur, flame sensor controls will
initiate 3 attempts at re−ignition before locking out unit
operation.
Combustion air inducer prepurges heat exchanger and
safely vents flue products.
Pressure switch proves combustion air inducer operation
before allowing gas valve to open.
Combustion air inducer operates only during heating
cycle.
Tubular Aluminized or Stainless Steel Heat
Exchanger
Tubular heat exchanger is constructed of aluminized or
stainless steel for superior resistance to corrosion and
oxidation.
Curving design allows complete exposure of heating
surfaces to supply air stream.
Round surfaces create minimum air resistance and allow
air to surround all surfaces for excellent heat transfer.
Compact design reduces space requirements in unit
cabinet.
Heat exchanger has been laboratory life cycle tested.
Inshot Burners
Aluminized steel inshot burners provide efficient trouble
free operation.
Burner venturi mixes air and gas in correct proportion for
proper combustion.
Burner assembly is removeable from the unit as a single
component for ease of service. Each burner may be
removed individually.
Limit Control
Factory installed and accurately located.
Limit control has fixed temperature setting and protects
heating system from abnormal operating conditions.
Combustion Air Inducer
Combustion air inducer prepurges heat exchanger and
safely vents combustion products.
Blower motor has sleeve bearings and is thermally
protected.
Pressure switch prevents unit operation in case of
blockage of combustion air inlet or flue outlet.
Combustion air inducer on LF24−100, −115, −125, −145
units may be rotated 90_to left or right of vertical to
facilitate installation.
Venting
Units may be vented horizontally or vertically.
LF24 units are approved for installation with single wall
and type B−1 double wall vent pipe.
OPTIONS
LPG/Propane Conversion Kit
Conversion kit is required for field changeover from
natural gas.
Kit is not furnished and must be ordered extra.
Controls
Includes: 24 volt main gas valve with 100% safety shutoff,
main shutoff valve, gas pressure regulation (natural &
LPG/propane gas models), limit control, transformer and
combination ignition/fan timer control board.
Combination Direct Spark Ignition/Fan Timer Control
Solid−state control board contains all necessary controls
and relays to operate unit.
Includes: Fan timer control − fan on 45 seconds (fixed), fan
off 150 seconds (fixed), terminal strip for thermostat
connections, diagnostic LED for troubleshooting,
continuous fan operation.
Transformer
120V/24V transformer furnished as standard.
OPTIONS
Thermostat
See Thermostat bulletins in Controls section and Lennox
Price Book for a complete list of thermostats.
Direct Drive Fan
All models are equipped with efficient and quiet operating
direct drive fan.
Cabinet
Constructed of heavy gauge painted steel.
Inside cabinet insulation keeps outer cabinet surface
temperatures low.
Adjustable louvers are furnished on cabinet for control of
air flow direction.
Wiring junction box is conveniently located on outside of
cabinet for easy access. Box contains all electrical and
safety controls.
Terminal strip provided for thermostat connections.
3/8  x 16 rivetnuts are located on the top of cabinet for
suspending unit. See dimension drawing.
OPTIONS
Discharge Nozzles
To direct discharge air from unit heater.
Available in 30_, 45_, 60_and 90_style.
Fully assembled from heavy−gauge steel.
Paint finish matches unit heater.
See Dimension Drawings.
Hanging Bracket Kit
Used to suspend unit heaters on two pipe hangers.
Kit contains two brackets and all necessary hardware.
Pipe hangers (3/4 in.) are not furnished and must be field
provided.

LF24 − 100,000 to 400,000 Btuh / Page 3
SPECIFICATIONS − LF24−100 to LF24−200
Gas
Heating
Performance
Model No. − Stainless Steel LF24−100S LF24−115S LF24−145S LF24−175S LF24−200S
Model No. − Aluminized Steel LF24−100A LF24−115A LF24−145A LF24−175A LF24−200A
Heating Capacity Input − Btuh 100,000 115,000 145,000 172,500 195,000
Output − Natural − Btuh 80,500 92,000 116,000 138,000 156,000
Steady State Efficiency − Natural 80.5% 80.0% 80.0% 80.0% 80.0%
Connections Flue size − in. (round) 1414142525
Gas Piping Size 1/2 1/2 1/2 1/2 1/2
Fan Data Air Volume − cfm 1900 1900 1900 2200 2200
Number of Fans 1 1 1 1 1
Diameter − in. 16 16 16 16 16
Number of blades 4 4 5 5 5
Number of Motors 1 1 1 1 1
Motor Output − hp 1/8 1/8 1/8 1/8 1/8
RPM 1075 1075 1075 1075 1075
Weight Data Net Weight − lbs. 125 125 130 145 145
Shipping Weight − lbs. 140 140 150 165 165
ELECTRICAL DATA
Line voltage data − 60hz 115 volts − 1 phase
Motor amps 2.1 2.1 2.1 2.1 2.1
Total unit amps 6.0 6.0 6.0 6.0 6.0
Optional Accessories − Must Be Ordered Extra
Discharge
Nozzle
30_− 94K94 SS S
94K95 S S
94K96
45_− 95K98 S S S
95K99 S S
95K00
60_− 16L28 S S S
16L29 S S
16L30
90_− 15L96 S S S
15L97 S S
15L98
Hanging Bracket Kit 87277 S S S S S
3High Altitude
Pressure Switch Kit 10K73 S S S S − − −
LPG/Propane Kit
45L85 S
63J56 S S S
20L07 S
63J57
12−1/8 x 4 in. diameter adaptor is furnished with unit for flue connection.
22−1/4 x 2−3/4 in. rectangular to 5 in. round adaptor is furnished with unit for flue connection.
3Required for proper unit operation at altitudes over 5501 feet above sea level.

LF24 − 100,000 to 400,000 Btuh / Page 4
SPECIFICATIONS − LF24−230 to LF24−400
Gas
Heating
Performance
Model No. − Stainless Steel LF24−230S LF24−250S LF24−300S LF24−345S LF24−400S
Model No. − Aluminized Steel LF24−230A LF24−250A LF24−300A LF24−345A LF24−400A
Heating Capacity Input − Btuh 230,000 250,000 300,000 345,000 390,000
Output − Natural − Btuh 184,000 201,250 241,500 276,000 312,000
Steady State Efficiency − Natural 80.0% 80.5% 80.5% 80.0% 80.0%
Connections Flue size − in. (round) 1515152626
Gas Piping Size 3/4 3/4 3/4 3/4 3/4
Fan Data Air Volume − cfm 4400 4400 4400 4400 4400
Number of Fans 2 2222
Diameter − in. 16 16 16 16 16
Number of blades 5 5555
Number of Motors 2 2222
Motor Output − hp 1/8 1/8 1/8 1/8 1/8
RPM 1075 1075 1075 1075 1075
Weight Data
Net Weight − lbs. 225 270 280 285 285
Shipping Weight − lbs. 270 285 305 310 310
ELECTRICAL DATA
Line voltage data − 60hz 115 volts − 1 phase
Motor amps 2.1 (4.2) 2.1 (4.2) 2.1 (4.2) 2.1 (4.2) 2.1 (4.2)
Total unit amps 9.0 9.0 9.0 9.0 9.0
Optional Accessories − Must Be Ordered Extra
Discharge
Nozzle
30_− 94K96 S S S S S
45_− 95K00 S S S S S
60_− 16L30 S S S S S
90_− 15L98 S S S S S
Hanging Bracket Kit 87277 S S S S S
LPG/Propane Kit 45L88 S S
63J57 S S
20L06 S
12−1/4 x 2−3/4 in. rectangular to 5 in. round adaptor is furnished with unit for flue connection.
22−1/4 x 2−3/4 in. rectangular to 6 in. round adaptor is furnished with unit for flue connection.

LF24 − 100,000 to 400,000 Btuh / Page 5
HIGH ALTITUDE DERATE
Unit may be fired at full input up to 2000 feet above sea level. Above 2000 feet, manifold pressure must be adjusted on
some units. Adjust pressure regulator to pressure shown in tables. If unit is installed at an altitude greater than 7500 ft.
unit must be derated by 4 percent for each additional 1000 ft. above 7500 ft. In Canada, certification for installation at alti-
tudes over 4500 feet above sea level is the jurisdiction of the local authorities.
NOTE − This is the only permissible derate for the units.
Model
No.
Natural Gas Manifold Pressure − in. w.c.
0−2000 ft. 2000−2500 ft. 2500−3500 ft. 3500−4500 ft. 4500−5500 ft. 5500−6500 ft. 6500−7500 ft.
LF24−100
LF24−115
LF24−300
No
adjustment
No
adjustment
No
adjustment
No
adjustment 3.4 3.3 3.2
LF24−145 No
adjustment 3.4 3.3 3.2 3.1 3.0 2.9
LF24−175
LF24−230
No
adjustment
No
adjustment
1No
adjustment
1No
adjustment
1No
adjustment
1No
adjustment
1No
adjustment
LF24−200
LF24−250
LF24−345
LF24−400
No
adjustment
No
adjustment
No
adjustment 3.4 3.3 3.2 3.1
1LF24−175 Combustion air inducer pressure switch must be replaced at altitudes from 2500−7500 ft. Order 10K73 pressure switch.
Model
No.
LPG/Propane Manifold Pressure − in. w.c.
0−2000 ft. 2000−2500 ft. 2500−3500 ft. 3500−4500 ft. 4500−5500 ft. 5500−6500 ft. 6500−7500 ft.
LF24−100
LF24−115
LF24−300
No
adjustment
No
adjustment
No
adjustment
No
adjustment 8.7 8.4 8.1
LF24−145 No
adjustment 8.7 8.4 8.1 7.8 7.5 7.2
LF24−175
LF24−230
No
adjustment
No
adjustment
1No
adjustment
1No
adjustment
1No
adjustment
1No
adjustment
1No
adjustment
LF24−200
LF24−250
LF24−345
LF24−400
No
adjustment
No
adjustment
No
adjustment 9.2 8.9 8.6 8.3
1LF24−175 Combustion air inducer pressure switch must be replaced at altitudes from 2500−7500 ft. Order 10K73 pressure switch.
THROW DATA
Model No. Air Volume 1Effective Throw
cfm feet
LF24−100, LF24−115,
LF24−145 1900 60
LF24−175, LF24−200 2200 65
LF24−230, LF24−250,
LF24−300, LF24−345,
LF24−400
4400 80
NOTE − Adjustable horizontal louvers on unit allow a variation in throw and spread.
1Throw terminates where velocity reaches 50 ft.per minute.
1RECOMMENDED MOUNTING HEIGHT
Model No. Feet
LF24−100, LF24−115 16
LF24−145, LF24−175,
LF24−200 20
LF24−230, LF24−250,
LF24−300, LF24−345,
LF24−400
30
1Recommended maximum mounting height from floor to bottom of unit. At heights
greater than shown air throw distance and air temperature at floor level is affected.
INSTALLATION cLEARANCES
Top 6 inches
Sides 6 inches
Rear 18 inches
Bottom 0 inches
Flue 6 inches
NOTE − Provide adequate clearance for servicing.
See Installation Instructions for further installation considerations.
MAXIMUM HORIZONTAL VENT LENGTHS
No. of
Elbows
LF24−100
−115−145
−175−200
LF24−230
−250
−300
LF24−345 LF24−400
1 25 35 31 21
2 20 30 22 12
3 15 25 13 3
4 10 20 4 − − −
5 5 15 − − − − − −
6− − − 10 − − − − − −
7− − − 5− − − − − −

LF24 − 100,000 to 400,000 Btuh / Page 6
DIMENSIONS − INCHES (MM)
1/2
(13)
TOP VIEW
SIDE VIEW
ADJUSTABLE
LOUVERS
GAS
VALVE
HEAT
EXCHANGER
DIRECT
DRIVE FAN
FLUE
OUTLET
ELECTRICAL INLETS
3/8−16 RIVETNUTS
FOR UNIT SUSPENSION
AIR
FLOW
COMBUSTION AIR
INDUCER
FRONT VIEW
A
C
D
E
1NOTE − Two rivetnuts are furnished on
LF24−100−115 −145,−175 and −200 models.
− Four rivetnuts are furnished on
LF24−230−250−300−345 and −400 models.
B
*7−5/8
(194) 1/2
(13)
1Furnished on
LF24−230,
LF24−250,
LF24−300,
LF24−345 and
LF24−400
Models Only.
F
NOTE − Single fan model shown, LF24−100−115−145−175 and −200.
LF24−230−250−300−345 and −400 models have two fans.
32−3/16
(817)
31−5/16
(795)
Model
No.
A B C D E F
in. mm in. mm in. mm in. mm in. mm in. mm
LF24−100
LF24−115
LF24−145
20−3/16 512 11−1/2 292 19−1/16 484 11−3/4 298 3−1/4 83 7−7/8 200
LF24−175
LF24−200 23−1/8 588 11−1/2 292 22−1/16 560 8−1/2 337 3−1/4 83 8−11/16 220
LF24−230
LF24−250
LF24−300
41−1/8 1045 3−11/16 97 40 1016 17−3/4 451 3−1/2 89 8−11/16 220
LF24−345
LF24−400 41−1/8 1045 3−11/16 97 40 1016 17−1/2 445 3−1/2 89 9−13/16 248

LF24 − 100,000 to 400,000 Btuh / Page 7
ACCESSORY DIMENSIONS − INCHES (MM)
60 deg
A
23−1/2
(597)
28−3/4
(730)
A
30−7/8
(784)
31−3/4(
806)
30 deg
A
25−3/16
(640)
18−1/4
(464)
27−7/8
(708)
45 deg
A
28−1/8
(714)
30_Discharge Nozzle
90_Discharge Nozzle60_Discharge Nozzle
45_Discharge Nozzle
25−3/16
(640)
18
(457)
25−3/16
(640)
25−3/16
(640)
Model Usage A
in. mm
LF24−100
LF24−115 18−1/4 464
LF24−145
LF24−175
LF24−200
21−1/4 540
LF24−230
LF24−250
LF24−300
LF24−345
LF24−400
39−1/4 997

GUIDE SPECIFICATIONS
T−Class Packaged Gas / Electric 7.5 to 12.5 tons / Page 8
This specification specifies [Lennox Industries LF24] gas−fired unit heaters. Revise specification section
number and title below to suit project requirements, specification practices and section content. Refer to CSI
MasterFormat for other section numbers and titles.
This specification utilizes the Construction Specifications Institute (CSI) Manual of Practice, including
MasterFormatt, SectionFormattand PageFormatt. Optional text and text requiring a decision is indicated
by bold brackets[ ] and proprietary information is indicated by bold italic brackets[ ]; delete text not required
in final copy of specification. Specifier Notes typically precede specification text; delete notes in final copy of
specification. Trade/brand names with appropriate symbols typically are used in Specifier Notes; symbols are
not used in specification text. Metric conversion, where used, is soft metric conversion.
SECTION 23 55 33
FUEL−FIRED UNIT HEATERS
PART 1 GENERAL
1.1 SUMMARY
A. Section Includes: Gas−Fired unit heaters
Specifier Note: Revise paragraph below to suit project requirements. Add section numbers and titles per CSI
MasterFormat and specifier’s practice.
B. Related Sections:
Specifier Note: Article below may be omitted when specifying manufacturer’s proprietary products and recommended
installation. Retain Reference Article when specifying products and installation by an industry reference standard. If
retained, list standard(s) referenced in this section. Indicate issuing authority name, acronym, standard designation and
title. Establish policy for indicating edition date of standard referenced. Conditions of the Contract or Division 1
References Section may establish the edition date of standards. This article does not require compliance with standard,
but is merely a listing of references used. Article below should list only those industry standards referenced in this
section. Retain only those reference standards to be used within the text of this Section. Add and delete as required for
specific project.
1.02 REFERENCES
A. Certifications:
1. CSA International
2. For use with natural or LPG/propane gas
3. California Energy Commission (CEC)
B. ISO 9001, units manufactured to quality standard
Specifier Note: Article below should be restricted to statements describing design or performance requirements and
functional (not dimensional) tolerances of a complete system. Limit descriptions to composite and operational properties
required to link components of a system together and to interface with other systems.
1.03 SYSTEM DESCRIPTION
A. Electrical Requirements:
1. 60 Hz.
2. 115 V
3. Single phase
4. 115V/24V or 120V/24V transformer
B. Fuel Requirements: [Natural gas] [and][/][or] [LPG/propane]
Specifier Note: Article below includes submittal of relevant data to be furnished by Contractor before, during or after
construction. Coordinate this article with Architect’s and Contractor’s duties and responsibilities in Conditions of the
Contract and Division 1 Submittal Procedures Section.
1.04 SUBMITTALS
A. General: Submit listed submittals in accordance with Conditions of the Contract and Division 1 Submittal Procedures.
B. Product Data: Submit product data for specified products.
C. Shop Drawings:
1. Submit shop drawings in accordance with Section [01330 − Submittal Procedures].
2. Indicate:
a. Equipment, piping and connections, together with valves, strainers, control assemblies, thermostatic
controls, auxiliaries and hardware and recommended ancillaries which are mounted, wired and piped
ready for final connection to building system, its size and recommended bypass connections.
b. Piping, valves and fittings shipped loose showing final location in assembly.
c. Control equipment shipped loose, showing final location in assembly.
d. Field wiring diagrams.
e. Dimensions, internal and external construction details, installation clearances, recommended method of
installation, sizes and location of mounting bolt holes.
f. Detailed composite wiring diagrams for control systems showing factory installed wiring and equipment
on packaged equipment or required for controlling devices or ancillaries, accessories, controllers.

GUIDE SPECIFICATIONS
T−Class Packaged Gas / Electric 7.5 to 12.5 tons / Page 9
D. Quality Assurance:
1. Test Reports: Certified test reports showing compliance with specified performance characteristics and physical
properties.
2. Certificates: Product certificates signed by manufacturer certifying materials comply with specified performance
characteristics and criteria and physical requirements.
3. Manufacturer’s Instructions: Manufacturer’s installation instructions.
Specifier Note: Coordinate paragraph below with Part 3 Field Quality Requirements Article herein. Retain or delete as
applicable.
E. Manufacturer’s Field Reports: Manufacturer’s field reports specified herein.
F. Closeout Submittals: Submit the following:
1. Warranty: Warranty documents specified herein.
2. Operation and Maintenance Data: Operation and maintenance data for installed products in accordance with
Division 1 Closeout Submittals (Maintenance Data and Operation Data) Section. Include methods for maintaining
installed products and precautions against cleaning materials and methods detrimental to finishes and
performance. Include names and addresses of spare part suppliers.
3. Provide brief description of unit, with details of function, operation, control and component service.
4. Commissioning Report: Submit commissioning reports, report forms and schematics in accordance with Section
01810 − Commissioning.
1.05 QUALITY ASSURANCE
A. Qualifications:
1. Installer experienced in performing work of this section who has specialized in installation of work similar to that
required for this project.
1.06 DELIVERY, STORAGE & HANDLING
A. General: Comply with Division 1 Product Requirements.
B. Ordering: Comply with manufacturer’s ordering instructions and lead−time requirements to avoid construction delays.
C. Packing, Shipping, Handling and Delivery:
1. Deliver materials in manufacturer’s original, unopened, undamaged containers with identification labels intact.
2. Ship, handle and unload units according to manufacturer’s instructions.
D. Storage and Protection:
1. Store materials protected from exposure to harmful weather conditions.
2. Factory shipping covers to remain in place until installation.
Specifier Note: Coordinate article below with Conditions of the Contract and Division 1 Closeout Submittals (Warranty).
1.07 WARRANTY
A. Project Warranty: Refer to Conditions of the Contract for project warranty provisions.
B. Manufacturer’s Warranty: Submit, for Owner’s acceptance, manufacturer’s standard warranty document executed by
authorized company official. Manufacturer’s warranty is in addition to, and not a limitation of, other rights Owner may have
under Contract Documents.
Specifier Note: Coordinate paragraph below with manufacturer’s warranty requirements.
C. Warranty: Commencing on Date of Installation.
Specifier Note: Refer to Lennox Equipment Limited Warranty certificate included with equipment for details.
1. Heat Exchanger:
a. Aluminized Steel: 10 years, limited (non−residential applications)
b. Stainless Steel: 15 years, limited (non−residential applications)
2. Solid−State Ignition Module: 1 year, limited (non−residential applications)
3. All other components: 1 year limited

GUIDE SPECIFICATIONS
T−Class Packaged Gas / Electric 7.5 to 12.5 tons / Page 10
PART 2 PRODUCTS
Specifier Note: Retain article below for proprietary method specification. Add product attributes, performance
characteristics, material standards and descriptions as applicable. Use of such phrases as or equal" or or approved
equal" or similar phrases may cause ambiguity in specifications. Such phrases require verification (procedural, legal and
regulatory) and assignment of responsibility for determining or equal" products.
2.01 [Lennox LF24] GAS−FIRED UNIT HEATERS
A. Manufacturer:[ Lennox Industries]
1. Contact: [2100 Lake Park Blvd., Richardson, TX 75080; Telephone: (800) 453−6669; Web site:
www.lennox.com]
B. General:
1. Air−Flow: Horizontal
2. Venting
a. Horizontal
b. Vertical
3. All units to be shipped completely assembled at the factory
4. Hanging brackets to be supplied by manufacturer for field mounting of unit heater
5. Controls to be factory installed and wired
6. All units must pass a factory run−test before shipping
7. Installer to:
a. Make unit gas supply connections
b. Make electrical connections
c. Mount thermostat
d. Make flue connections
Specifier Note: LF24 models with BTUH requirements: 030 (30,000 Btuh), 045 (45,000 Btuh), 060 (60,000 Btuh), 075 (75,000
Btuh), 100 (100,000 Btuh), 115 (115,000 Btuh), 145 (145,000 Btuh), 175 (175,000 Btuh), 200 (200,000 Btuh), 230 (230,000 Btuh),
250 (250,000 Btuh), 300 (300,000 Btuh), 345 (345,000 Btuh), and 400 (400,000 Btuh).
8. See schedule for Btuh of unit required
C. [Proprietary] Products/Systems: [LF24] Gas−fired unit heaters includes the following:
1. Cabinet:
a. Pre−painted
b. Heavy gauge galvanized steel construction
c. Internally insulated cabinet
d. Adjustable louvers
e. Contains all electrical and safety controls
Specifier Note: Wiring Junction box located inside the cabinet on LF24 models 030, 045, 060 and 075. Wiring Junction box
mounted on the exterior of the cabinet on LF24 models 100, 115, 145, 175, 200, 230, 250, 300, 345, and 400.
f. Wiring Junction box mounted inside cabinet or on the exterior of the cabinet
2. Heating System:
a. Combination gas control valve
1. 24 volt
2. Manual shutoff valve
3. Dual Valve:
a. Pressure regulator
b. Automatic electric valve
b. Solid−state igniter
1. Direct−spark
2. Intermittent spark
c. Electronic flame sensor
d. Combustion air inducer
1. Pre−purge heat exchanger
2. Pressure switch to prove operation
3. Operates only during heating
4. Blower motor is thermally protected
e. Heat Exchanger:
1. Tubular
Specifier Note: Aluminized Steel heat exchanger is available on all LF24 models. Stainless Steel heat exchanger is only
available on the LF24 models 100, 115, 145, 175, 200, 230, 250, 300, 345, and 400.
2. [Aluminized Steel] [and][/][or] [Stainless steel]
3. Curving design
4. Laboratory lifecycle tested
f. Inshot burners:

GUIDE SPECIFICATIONS
T−Class Packaged Gas / Electric 7.5 to 12.5 tons / Page 11
1. Aluminized steel
2. Venturi to mix gas and air for proper combustion
3. Assembly to be removable as a single component
4. Individual burner removable from assembly
g. Limit Control:
1. Factory installed
2. Fixed temperature setting
3. Protect heating system from abnormal operating conditions
3. Solid state control board
a. Fan timer control
b. Diagnostic LED for trouble shooting
c. Continuous fan operation
4. Low voltage terminal strip
5. Supply fan:
a. Motor:
1. Direct drive
2. Permanently lubricated
b. Propeller type fan blade
6. [Optional Accessories]:
a. [Thermostat]
Specifier Note: Air Flow Nozzles are only available on the LF24 models 100, 115, 145, 175, 200, 230, 250, 300, 345, and 400.
b.[Airflow Nozzles:]
1. [30°from horizontal]
2. [45°from horizontal]
3. [60°from horizontal]
4. [90°from horizontal]
Specifier Note: the High Altitude Pressure Switch Kit is only available on the LF24 models 100, 115, 145, and 175.
c. [High Altitude Pressure Switch Kit]
2.02 PRODUCT SUBSTITUTIONS
A. Substitutions: No substitutions permitted.
PART 3 EXECUTION
3.01 MANUFACTURER’S INSTRUCTIONS
Specifier Note: Article below is an addition to the CSI SectionFormat. Revise article below to suit project requirements and
specifier’s practice.
A. Compliance: Comply with manufacturer’s written data, including product technical bulletins, product catalog installation
instructions and product carton installation instructions.
3.02 EXAMINATION
A. Site Verification of Conditions: Verify substrate conditions, which have been previously installed under other sections, are
acceptable for product installation in accordance with manufacturer’s instructions.
3.03 INSTALLATION
A. Install [Lennox LF24] gas fired unit heaters in accordance with manufacture’s instructions and regulations of authorities
having jurisdiction.
END OF SECTION

REVISIONS
Sections Description of Change
Specifications LF24−300 − Changed flue diameter to 5 in.
Visit us at www.lennox.com
For the latest technical information, www.lennoxcommercial.com
Contact us at 1−800−4−LENNOX
NOTE − Due to Lennox’ ongoing committment to quality, Specifications, Ratings and Dimensions subject to change without notice and without incurring liability.
Improper installation, adjustment, alteration, service or maintenance can cause property damage or personal injury.
Installation and service must be performed by a qualified installer and servicing agency. ©2007 Lennox Industries Inc.