Trane GUNE-SVX001A-EN Installation and operating instructions

SAFETY WARNING
Only qualified personnel should install and service the equipment. The installation, starting up, and servicing of heating, ventilating, and air-
conditioning equipment can be hazardous and requires specific knowledge and training. Improperly installed, adjusted or altered equipment
by an unqualified person could result in death or serious injury. When working on the equipment, observe all precautions in the literature and
on the tags, stickers, and labels that are attached to the equipment.
Tubular Indoor Gas Fired Duct Furnace
Model Number
GUNE J30-09453
GUNE-SVX001A-EN
June 2014
Installation, Operation,
and Maintenance

© 2014 Trane All rights reserved GUNE-SVX001A-EN
Introduction
Readthismanualthoroughlybeforeoperatingorservicing
this unit.
Warnings, Cautions, and Notices
Safety advisories appear throughout this manual as
required.Yourpersonalsafetyandtheproperoperationof
this machine depend upon the strict observance of these
precautions.
The three types of advisories are defined as follows:
WARNING Indicates a potentially hazardous
situation which, if not avoided, could
result in death or serious injury.
CAUTIONsIndicates a potentially hazardous
situation which, if not avoided, could
result in minor or moderate injury. It
could also be used to alert against
unsafe practices.
NOTICE: Indicatesasituationthatcouldresultin
equipment or property-damage only
accidents.
WARNING
Proper Field Wiring and Grounding
Required!
Failure to follow code could result in death or serious
injury. All field wiring MUST be performed by qualified
personnel. Improperly installed and grounded field
wiring poses FIRE and ELECTROCUTION hazards. To
avoid these hazards, you MUST follow requirements for
field wiring installation and grounding as described in
NEC and your local/state electrical codes.
WARNING
Personal Protective Equipment (PPE)
Required!
Installing/servicing this unit could result in exposure to
electrical, mechanical and chemical hazards.
• Before installing/servicing this unit, technicians
MUST put on all PPE required for the work being
undertaken (Examples; cut resistant gloves/sleeves,
butyl gloves, safety glasses, hard hat/bump cap, fall
protection, electrical PPE and arc flash clothing).
ALWAYS refer to appropriate Material Safety Data
Sheets (MSDS)/Safety Data Sheets (SDS) and OSHA
guidelines for proper PPE.
• When working with or around hazardous chemicals,
ALWAYS refer to the appropriate MSDS/SDS and
OSHA/GHS (Global Harmonized System of
Classification and Labelling of Chemicals) guidelines
for information on allowable personal exposure
levels, proper respiratory protection and handling
instructions.
• If there is a risk of energized electrical contact, arc, or
flash, technicians MUST put on all PPE in accordance
with OSHA, NFPA 70E, or other country-specific
requirements for arc flash protection, PRIOR to
servicing the unit. NEVER PERFORM ANY
SWITCHING, DISCONNECTING, OR VOLTAGE
TESTING WITHOUT PROPER ELECTRICAL PPE AND
ARC FLASH CLOTHING. ENSURE ELECTRICAL
METERS AND EQUIPMENT ARE PROPERLY RATED
FOR INTENDED VOLTAGE.
Failure to follow instructions could result in death or
serious injury.

Introduction
GUNE-SVX001A-EN 3
For Your Safety
The use and storage of gasoline or other flammable
vapors and liquids in open containers in the vicinity
of this appliance is hazardous.
If you smell gas:
1. Open windows.
2. Don’t touch electrical switches.
3. Extinguish any open flame.
4. Immediately contact your gas supplier.
Approved for Use in California
Installer’s Responsibility
Installer Please Note: This equipment has been test
fired and inspected. It has been shipped free from defects
from our factory. However, shipment and installation
problems such as loose wires, leaks, and loose fasteners
may occur. It is the installer’s responsibility to inspect and
correct any problem that may be found.
Receiving Instructions
Inspect shipment immediately when received to
determine if any damage has occurred to the unit during
shipment. After the unit has been uncrated, check for any
visible damage to the unit. If any damage is found, the
consignee should sign the bill of lading indicating such
damage and immediately file claim for damage with the
transportation company.
General Safety Information
• The tubular duct furnace design is certified by ETL for
use with natural and propane (LP) gases. ANSI and
NFPAStandardsaswellasCanadianinstallationcodes
referred to in this manual are the ones that were
applicable at the time the design was certified. In
addition, the tubular duct furnace may be installed on
thedownstreamsideofacoolingunit,withoutneedof
a bypass duct.
• Installation must be made in accordance with local
codes, or in absence of local codes, with the latest
edition of the National Fuel Gas Code, ANSI
Standard Z223.1 (NFPA 54).
All of the ANSI and NFPA Standards referred to in
these installation instructions are those that were
applicable at the time the design of this appliance
was certified. The ANSI Standards are available from
the CSA Information Services, [phone], as well
as at www.ansi.org. The NFPA Standards are
available from the National Fire Protection
Association, 1 Batterymarch Park, Quincy, MA 02169,
as well as at www.nfpa.org. These duct furnaces are
designed for use in airplane hangars when installed
in accordance with current ANSI/NFPA No. 409 and in
public garages when installed in accordance with
current NFPA No. 88A and NFPA No. 88B.
If installed in Canada, the installation must conform
with local building codes, or in absence of local
building codes, with CSA-B149.1 “Installation Codes
for Natural Gas Burning Appliances and Equipment”
or CSA-B149.2 “Installation Codes for Propane Gas
Burning Appliances and Equipment.” These indoor
duct furnaces have been designed and certified to
comply with CSA 2.6. Also refer to “Aircraft Hangars,”
p. 10 and “Public Garages,” p. 10.
• Do not alter the duct furnace in any way or damage to
the unit and/or severe personal injury or death could
occur!
• This product must be installed by a licensed plumber
orgasfitterwheninstalledwithintheCommonwealth
of Massachusetts.
• Turn off the gas supply and disconnect all electric
power, including remote disconnects before servicing
unit. Follow proper lockout/tagout procedures to
ensure the power can not be inadvertently energized
andthegascan notbeinadvertentlyturnedon.Failure
to turn off gas or disconnect power before servicing
could result in death or serious injury.
WARNING
Safety Alert!
You MUST follow all instructions below. Failure to do so
could result in death or serious injury.
WARNING
Hazardous Gases and Flammable Vapors!
Failure to observe following instructions could result in
death or serious injury. Exposure to hazardous gases
from fuel substances have been shown to cause cancer,
birth defects or other reproductive harm. Improper
installation, adjustment, alteration, service or use of
this product could cause flammable mixtures or lead to
excessive carbon monoxide. To avoid hazardous gases
and flammable vapors follow proper installation and
set up of this product and all warnings as provided in
this manual.
WARNING
Toxic Hazard!
Install, operate, and maintain unit in accordance with
the manufacturer’s instructions to avoid exposure to
fuel substances, or substances from incomplete
combustion, which can cause death or serious illness.
The state of California has determined that these
substances may cause cancer, birth defects, or other
reproductive harm.
WARNING
Safety Alert!
You MUST follow all instructions below. Failure to do so
could result in death or serious injury.

Introduction
4GUNE-SVX001A-EN
• Follow installation instructions CAREFULLY to avoid
creating unsafe conditions. All wiring should be done
and checked by a qualified electrician, using copper
wire only. All external wiring must conform to
applicable local codes, and to the latest edition of the
National Electric Code
ANSI/NFPA No. 70.
• Allgasconnectionsshouldbemadeandleak-testedby
a suitable qualified individual, per instructions in this
manual. Also follow procedures listed in “Gas
Equipment Start-Up,” p. 30.
• Use only the fuel for which the duct furnace is
designed (see rating plate). Using LP gas in a heater
that requires natural gas, or vice versa, will create the
risk of gas leaks, carbon monoxide poisoning and
explosion.
Important: Do not attempt to convert the duct
furnace for use with a fuel other than
the one intended. Such conversion is
dangerous, as it could create the risks
listed previously.
• Use only the fuel for which the heater is designed (see
rating plate). Using LP gas in a heater that requires
natural gas, or vice versa, will create the risk of gas
leaks, carbon monoxide poisoning and explosion.
• Make certain that the power source conforms to the
electrical requirements of the heater.
• Do not depend upon a thermostat or other switch as
a sole means of disconnecting power when installing
or servicing heater. Always disconnect power at main
circuit breaker as described above. Failure to do so
could result in fatal electric shock.
• Special attention must be given to any grounding
information pertaining to this heater. To prevent the
risk of electrocution, the heater must be securely and
adequatelygrounded.Thisshouldbeaccomplishedby
connecting a grounded conductor between the
service panel and the heater. To ensure a proper
ground, the grounding means must be tested by a
qualified technician.
• Do not insert fingers or foreign objects into the heater
or its combustion air moving device. Do not block or
tamper with the heater in any manner while in
operation or just after it has turned off, as some parts
may be hot enough to cause injury.
• This heater is intended for general heating
applications ONLY. It must NOT be used in potentially
dangerous locations such as flammable, explosive,
chemical-laden or wet atmospheres.
• In cases in which property damage may result from
malfunction of the heater, a backup system or a
temperature sensitive alarm should be used.
• Theopenendofgaspipingsystemsbeingpurgedshall
not be discharged into areas where there are sources
of ignition or into confined spaces UNLESS
precautions are taken as follows: 1) by ventilation of
the space, 2) by control of purging rate, 3) by
elimination of all hazardous conditions. All
precautionsmustbetakentoperformthisoperationin
a safe manner!
Unless otherwise specified, the following conversions
may be used for calculating SI unit measurements:
Copyright
Thisdocumentandtheinformationinitarethepropertyof
Trane, and may not be used or reproduced in whole or in
part without written permission. Trane reserves the right
torevisethispublicationatanytime,andtomakechanges
to its content without obligation to notify any person of
such revision or change.
Trademarks
All trademarks referenced in this document are the
trademarks of their respective owners.
Revision History
GUNE-SVX001A-EN (16 Jun 2014)
• First version of this literature
1 foot = 0.305 m 1 inch = 25.4 mm
1 gallon = 3.785 L 1 pound = 0.453 kg
1 psig = 6.894 kPa 1 cubic foot = 0.028m3
1000 BTU per hour = 0.293 kW 1 inch water column = 0.249 kPa
1000 BTU/Cu.Ft. = 37.5 MJ/m3 Liter/second = CFM x 0.472
Meter/second = FPM ÷ 196.8

GUNE-SVX001A-EN 5
Table of Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Warnings, Cautions, and Notices . . . . . . . . 2
General Safety Information . . . . . . . . . . . . . 3
Copyright . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Model Number Description . . . . . . . . . . . . . . . 6
General Information . . . . . . . . . . . . . . . . . . . . . 7
Dimensional Data and Weights . . . . . . . . . . . 8
Performance Data . . . . . . . . . . . . . . . . . . . . . . . 9
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Locating Units . . . . . . . . . . . . . . . . . . . . . . . . 10
Clearances . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Accessibility Clearance . . . . . . . . . . . . . . 10
Atmospheric Considerations . . . . . . . . . . 10
Aircraft Hangars . . . . . . . . . . . . . . . . . . . . 10
Public Garages . . . . . . . . . . . . . . . . . . . . . 10
Ductwork . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Air Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Combustion Inlet Air Ventilation . . . . . . . 11
Bypass . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Suspension . . . . . . . . . . . . . . . . . . . . . . . . 12
Conversion of access side . . . . . . . . . . . . 12
Gas Pipe Sizing . . . . . . . . . . . . . . . . . . . . . 13
Pipe Sizing . . . . . . . . . . . . . . . . . . . . . . . . 13
Pipe Installation . . . . . . . . . . . . . . . . . . . . 14
Venting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Venting for Power Vented Duct Furnaces
(Category III) . . . . . . . . . . . . . . . . . . . . . . . 16
Vertically Vented Duct Furnaces (Category III)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Horizontally Vented Duct Furnaces
(Category III) . . . . . . . . . . . . . . . . . . . . . . . 17
Combustion Air . . . . . . . . . . . . . . . . . . . . 20
Exhaust Venting . . . . . . . . . . . . . . . . . . . . 21
Electrical Connections . . . . . . . . . . . . . . . . . . . 25
Thermostat Wiring and Location . . . . . . 25
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Tubular Duct Furnace Direct Spark Ignition 27
Explanation of Controls . . . . . . . . . . . . . . 27
Start-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Shut Down . . . . . . . . . . . . . . . . . . . . . . . . .27
Gas Input Rate . . . . . . . . . . . . . . . . . . . . . .28
Tubular Duct Furnace—High Altitude Dera-
tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Gas Equipment Start-Up . . . . . . . . . . . . . . . . .30
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Periodic Service . . . . . . . . . . . . . . . . . . . . . . .31
Identification of Parts Tubular Duct Furnace
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
How To Order Replacement Parts . . . . . . . .33
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . .34
Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38

6GUNE-SVX001A-EN
Model Number Description
Digit 1 — Gas Heating
Equipment
G = Gas Heating Equipment
Digit 2 — Product Type
U = Tubular Duct Furnace
Digit 3 — Fuel Type
N=NaturalGas
P = Propane Gas (LP)
Digit 4 — Developmental
Sequence
E = Current Developmental
Sequence
Digits 5, 6, 7 — Input Capacity
(MBh)
010 = 100
015 = 150
020= 200
025= 250
030= 300
035= 350
040= 400
Digit 8 — Main Power Supply
A = 115/60/1
B = 230/60/1
C = 208/60/3
D = 230/60/3
E = 460/60/3
F = 575/60/3
G = 208/60/1
Digit 9 — Gas Control Option
H = Electronic Modulating w/Room
Sensing
J = Electronic Modulating w/Duct
Thermostat
L = Electronic Modulation
w/External 4–20 mA Input
M = Electronic Modulation
w/External 0–10 Vdc Input
T = Single-Stage, Direct Spark
Ignition
V = Two-Stage, Direct Spark Ignition
W = Electronic Modulation w/Duct
Thermostat/Room Override Stat
Digit 10 — Design Sequence
A=FirstDesign
Digit 11 — Heat Exchanger
Material
1 = Standard (Aluminized Steel)
2 = 409 Stainless Steel
Digit 12, 13, 14 — Reserved for
Future Use
0=NotUsed
Digit 15 — Miscellaneous
0=None
B = Air Pressure Switch for Above
5,000 Feet
G = Horizontal and Vertical Louvers
W = Stainless Steel Drain Pan
12345678910111213141516
GUNE020AHA10000B

GUNE-SVX001A-EN 7
General Information
Important: It is theequipment owners responsibilityto
provide any scaffolding or other apparatus
required to perform emergency service or
annual/periodic maintenance to this
equipment
The Tubular Indoor Gas-Fired Duct Furnace is a factory
assembled, power vented, and low static pressure type
duct furnace with a low profile cabinet. The duct furnace
can also be easily field converted to separated
combustion. The design is certified by ETL as providing a
minimum of 82 percent thermal efficiency, and approved
for use in California. Do not alter these units inany way. If
you have any questionsafter readingthis manual,contact
the manufacturer.
Figure 1. Front
Figure 2. Back

8GUNE-SVX001A-EN
Dimensional Data and Weights
Table 1. Dimensional data and weights—tubular duct furnace dimensions, inches (mm)
Unit Capacity 100 150 200 250 300 350 400
“A” Overall Unit Height 10.3 13.7 17 20.2 23.5 26.7 30
(262) (348) (432) (513) (597) (678) (762)
“B” Height to Centerline Flue 7.6 10.5 11.9 6.8 8.4 10 11.6
(193) (267) (302) (173) (213) (254) (295)
“C” Height to Gas Connection 2.5 3.7 5.3 7 7 8.7 10.3
(64) (94) (135) (178) (178) (221) (262)
“D” Opening Height, Front & Rear 8.5 11.7 15 18.2 21.5 24.7 28
(216) (297) (381) (462) (546) (627) (711)
“E” Overall Unit Depth 32.7 32.7 32.7 33.5 33.5 33.5 33.5
(831) (831) (831) (851) (851) (851) (851)
“F” Flue Size Diameter 5556666
(127) (127) (127) (152) (152) (152) (152)
“G” Air Inlet Size Diameter 5556666
(127) (127) (127) (152) (152) (152) (152)
Gas Inlet, Natural Gas, inches 1/2 1/2 1/2 3/4 3/4 3/4 3/4
Gas Inlet, Natural Gas, inches 1/2 1/2 1/2 3/4 3/4 3/4 3/4
Approximate Unit Weight, lb (kg) 160 221 250 270 296 321 355
(73) (100) (113) (122) (134) (146) (161)
Approximate Ship Weight, lb (kg) 270 331 360 403 429 454 488
(122) (150) (163) (183) (195) (206) (221)
Figure 3. Tubular duct furnace dimensions
65.500
16.5
HANGING
LOCATION
48.7
OPENING
FRONT & REAR
D
OPENING
FRONT & REAR
E
47.50
15.251
30.500 27.50
1.50
C
4
7.197
G
D9362
10.3
1.5
1.5
GAS
CONNECTION
1.000
32.5
PEEP
HOLE
A
F
REAR VIEW
TOP VIEW
SIDE VIEW
B
POWER
CONNECTION
ACCESS PANEL

GUNE-SVX001A-EN 9
Performance Data
Table 2. Tubular duct furnace performance data
Unit Size
Input
Output
MBh (kW) Min CFM (m3/s) Temp rise °F (°C) P.D. in. wc (kPa) Max CFM (m3/s) Temp rise °F (°C) P.D. in. wc (kPa)
(Max) MBh
(kW) (Min) MBh (kW)
100 100 50 82 758 100 0.07 2528 30 0.65
(29.3) (14.6) (24.0) (0.357) (56) (0.017) (1.193) (17) (0.16)
150 150 75 123 1137 100 0.03 3792 30 0.44
(43.9) (21.9) (36.0) (0.536) (56) (0.007) (1.789) (17) (0.11)
200 200 100 164 1517 100 0.04 5057 30 0.54
(58.6) (29.3) (48.0) (0.715) (56) (0.009) (2.386) (17) (0.13)
250 250 125 205 1896 100 0.08 6321 30 0.76
(73.2) (36.6) (60.0) (0.894) (56) (0.019) (2.983) (17) (0.19)
300 300 150 246 2275 100 0.03 7585 30 0.69
(87.8) (43.9) (72.0) (1.074) (56) (0.007) (3.579) (17) (0.16)
350 350 175 287 2654 100 0.07 8849 30 0.76
(102.5) (51.2) (84.1) (1.252) (56) (0.017) (4.176) (17) (0.19)
400 400 200 328 3034 100 0.08 10,114 30 0.70
(117.1) (58.6) (96.1) (1.431) (56) (0.019) (4.773) (17) (0.17)
Notes:
1. Ratings are shown for unit installations at elevations between 0 and 2,000 feet (610m).
2. For unit installations in U.S.A. above 2,000 feet (610 m), the unit input must be field derated 4 percent for each 1,000 feet (305 m) above sea level;
refer to local codes, or in absence of local codes, refer to the latest edition of the National Fuel Gas Code, ANSI Standard Z223.1 (NFPA 54).
3. For installations in Canada, any references to deration at altitudes in excess of 2,000 feet (610 m) are to be ignored. At altitudes of 2,000 to
4,500 feet (610 to 1372 m), the unit must be field derated and be so marked in accordance with the ETL certification.
4. See Table 10 and Table 11, p. 29 for U.S.A. and Canadian field deration information.
Figure 4. Temperature rise and pressure drop graph
Size 200
Size 250
Size 300
Size 350
Size 400
Size 150
Size 100
0
25
50
75
100
125
150
175
200
225
250
275
300
012345
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Pa
m3/s
Pressure Drop, inches W.C.
Size 150 Size 200 Size 250 Size 300 Size 350 Size 400
Size 100
6
11
16
21
26
31
36
41
46
51
56
10
20
30
40
50
60
70
80
90
100
0 2000 4000 6000 8000 10000
°C
Temperature Rise, °F
Airflow (CFM)

10 GUNE-SVX001A-EN
Installation
Locating Units
Important: Locationofunitheatersisrelateddirectlyto
the selection of sizes. Basic rules are as
follows,
Clearances
Maintain adequate clearances around air openings into
the combustion chamber:
Accessibility Clearance
Theductfurnacemusthave18 inches(457 mm)clearance
onthecontrolcabinetend.Provisionshouldalsobemade
to assure accessibility for recurrent maintenance
purposes.
Atmospheric Considerations
Atmospheres containing commercial solvents or
chlorinated hydrocarbons will produce corrosive acids
when coming in contact with the flames. This will greatly
reduce the life of the gas duct furnace and may void the
warranty. Avoid such areas.
Important: If the gas duct furnace is to be used in a
building classified as having a hazardous
atmosphere, the installation must comply
with the standards set by the National
Board of Fire Underwriters. Consult the
authorities having jurisdiction before
starting the job.
The duct furnace must be installed on the positive
pressure side of the air circulation blower.
Aircraft Hangars
In aircraft hangars, duct furnaces must be at least 10 feet
(3.05 m) above the upper surface of wings or engine
enclosuresofthehighestaircrafttobestoredinthehangar
and 8 feet (2.4 m) above the floor in shops, offices, and
other sections of the hangar where aircraft are not stored
and housed. Refer to current ANSI/NFPA No. 409,Aircraft
Hangars. In Canada, installation is suitable in aircraft
hangars when acceptable to the enforcing authorities.
Public Garages
In repair garages, duct furnaces must be installed in a
detached buildingor room separated from repair areas as
specifiedinthelatesteditionofNFPA 88B,RepairGarages.
In parking structures, duct furnaces must be installed so
thattheburnerflamesarelocateda minimumof18 inches
(457 mm) above the floor or protected by a partition not
less than 18 inches (457 mm) high. Refer to the latest
edition of NFPA 88A, Parking Structures.
In Canada, installation must be in accordance with the
latest edition of CSA B149 “Installation Codes for Gas
Burning Appliances and Equipment.”
Important:
•The duct furnace must be installed such that the gas
ignitioncontrolsystemisnotdirectlyexposedtowater
spray, rain, or dripping water.
•Duct furnaces should not be installed to maintain low
temperatures and/or freeze protection of buildings. A
minimum of 50°F (10°C) thermostat setting must be
maintained.
If duct furnaces are operated to maintain lower than 50°F
(10°C),hotfluegasesare cooledinsidetheheatexchanger
to the point where water vapor (a flue gas by-product)
condenses onto the heat exchanger walls. The result is a
mildly corrosive acid that prematurely corrodes the
aluminized steel heat exchanger and can actually drip
water down from the duct furnace onto the floor surface
below. Additional duct furnaces should be installed if a
minimum 50°F (10°C) thermostat setting cannot be
maintained.
NOTICE:
Equipment Damage!
Do not install unit heaters in corrosive of flammable
atmospheres! Premature failure of, or severe damage to
the unit will result!
NOTICE:
Equipment Damage!
Avoid locations where extreme drafts can affect burner
operation. Duct furnaces must not be installed in
locations where air for combustion would contain
chlorinated, halogenated or acidic vapors. If located in
such an environment, premature failure of the unit will
occur!
WARNING
Combustible Materials!
Failure to maintain proper clearance between the unit
heat exchanger, vent surfaces and combustible
materials could cause a fire which could result in death
or serious injury or property damage. Refer to Table 3
for proper clearances.
Table 3. Minimum safety clearances(a)
(a) When clearances required for accessibility are greater than the mini-
mum safety clearances, the accessibility clearances take precedence.
Sides 6 inches (152 millimeters)
Top 6 inches (152 millimeters)
Bottom 6 inches (152 millimeters)
Flue 6 inches (152 millimeters)