American Dryer Corp. Gas/Electric/Steam ML-55HS User manual

ADCPartNo.113000
For replacement parts, contact the reseller from which the dryer
was purchased or
AmericanDryerCorporation
88CurrantRoad
FallRiverMA02720-4781
Telephone:[phone] / Fax:[phone]
e-mail:[e-mail]
www.amdry.com
WARNING: Foryoursafetythe
informationinthismanualmustbe
followedtominimizetheriskoffireor
explosionorto prevent property damage,
personalinjury ordeath.
Donot store or usegasolineorother flammable
vaporandliquidsinthevicinityofthisorany
otherappliance.
WHAT DOYOU DO IFYOU SMELL GAS
* Donot trytolightany appliance.
* Donottouch any electricalswitch;donotuse
anyphoneinyourbuilding.
* Clearthe room, buildingorareaof all
occupants.
* Immediatelycallyourgassupplierfroma
neighbor'sphone. Follow the gassupplier's
instructions.
* Ifyou cannot reachyourgas supplier, callthe
firedepartment.
Installationand servicemustbeperformed bya
qualifiedinstaller,serviceagencyorthegas
supplier.
AVERTISSEMENT: Assurez-vous debien
suivreles instructionsdonnées danscette
noticepourréduireauminimum lerisque
d’incendieou d’explosionoupour évitertout
dommagematériel, touteblessureou lamort.
Nepasentreposer niutiliser d’essence ni
d’autresvapeursouliquidesinflammablesdans
levoisinage decetappareiloudetoutautre
appareil.
QUEFAIRE SI VOUS SENTEZ UNEODEUR
DEGAZ:
* Nepastenter d’allumer d’appareil.
* Netouchezàaucuninterrupteur. Nepas
vousservirdes téléphones se trouvantdans
lebâtimentoùvousvoustrouvez.
* Évacuezla pièce,lebâtimentou lazone.
* Appelezimmédiatementvotrefournisseurde
gazdepuisunvoisin. Suivezlesinstructions
dufournisseur.
* Sivousnepouvez rejoindrelefournisseur
degaz,appelez le servicedesincendies.
L’installationetl’entretiendoivent êtreassurés
paruninstallateurouunservice d’entretien
qualifiéouparle fournisseurdegaz.
ML-55HS
Installation Manual
(Gas/Electric/Steam)

Retain This Manual In ASafe Place For Future Reference
American Dryer Corporation products embody advanced concepts in engineering, design, and safety. If this product is
properly maintained, it will provide many years of safe, efficient, and trouble-free operation.
ONLY qualified technicians should service this equipment.
OBSERVE ALL SAFETY PRECAUTIONS displayed on the equipment or specified in the installation manual included with
the dryer.
The following “FOR YOUR SAFETY” caution must be posted near the dryer in a prominent location.
ML-55HS
FORYOURSAFETY
Donotstore or use gasoline or
otherflammablevaporsor
liquidsinthevicinityofthisor
anyother appliance.
POURVOTRESÉCURITÉ
Nepasentreposer ni utiliser d’essence
nid’autresvapeursou liquides
inflammablesdanslevoisinagedecet
appareiloude yout autre appareil.
We have tried to make this manual as complete as possible and hope you will find it useful. ADC reserves the right to make
changes from time to time, without notice or obligation, in prices, specifications, colors, and material, and to change or
discontinue models.
Important
For your convenience, log the following information:
DATE OFPURCHASE ____________________________ MODELNO. __________________________________________
RESELLER’SNAME _______________________________________________________________________________________
Serial Number(s) ________________________________________________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
Replacement parts can be obtained from your reseller or the ADCfactory. Whenorderingreplacement parts from the factory,
you can FAX your order to ADC at [phone] or telephone your order directly to the ADC Parts Department at
[phone]. Please specify thedryermodelnumberand serialnumberinaddition tothedescriptionandpartnumber,so
that your order is processed accurately and promptly.
“IMPORTANTNOTETOPURCHASER”
Informationmustbeobtainedfromyourlocalgassupplierontheinstructions
tobe followed if theusersmellsgas. These instructions mustbepostedina
prominentlocationnearthedryer.

CHILDRENSHOULDNOTBEALLOWEDTOPLAYONORNEARTHEDRYERS.
WARNING
CHILDRENSHOULDBESUPERVISEDIFNEARDRYERSINOPERATION.
DRYERSSHOULDNEVERBELEFTUNATTENDEDWHILEINOPERATION.
CAUTION
FORYOURSAFETY
DONOTDRYMOPHEADSINTHE DRYER.
DONOTUSEDRYERINTHEPRESENCEOFDRYCLEANINGFUMES.
“Caution: Label all wires prior to
disconnection when servicing controls.Wiring
errors can cause improper operation.”
«Attention: Lordes opérationsd’entretien
des commandes étiqueter tous fils avant
de les déconnecter. Toute erreur de
câblage peut étre une source de danger et
depanne.»
WARNING
UNDER NO CIRCUMSTANCESshouldthedryerdoorswitches, lint doorswitch, heat
safety circuit ever be disabled.
IMPORTANT
YOUMUSTDISCONNECTandLOCKOUTTHEELECTRICSUPPLYandTHEGAS
SUPPLYBEFOREANYCOVERSorGUARDSAREREMOVEDFROMTHEMACHINE
TOALLOWACCESS FORCLEANING,ADJUSTING,INSTALLATION,orTESTING
OF ANY EQUIPMENT per OSHA (Occupational Safety and Health Administration)
STANDARDS.

WARNING
The dryer must never be operated with any of the back guards, outer tops, or service
panelsremoved. PERSONALINJURYorFIRECOULDRESULT.
IMPORTANT
PLEASE OBSERVE ALL SAFETY PRECAUTIONS displayed on the equipment or
specified in the installation manual included with the dryer.
Dryersmust not beinstalled or stored in an area where it will be exposed to water or weather.
The wiring diagram for the dryer is located in the front electrical control box area.
DRYERMUSTNEVERBEOPERATEDWITHOUTTHELINTFILTER(SCREEN)IN
PLACE,EVENIFANEXTERNALLINTCOLLECTIONSYSTEMISUSED.
WARNING

Table of Contents
SECTION I
IMPORTANT INFORMATION............................................................................... 3
A. ReceivingandHandling ............................................................................................................... 3
B. SafetyPrecaution ........................................................................................................................ 4
SECTION II
SPECIFICATIONS/COMPONENT IDENTIFICATION ....................................6
A. Specifications.............................................................................................................................. 6
B. ComponentIdentification............................................................................................................. 8
SECTION III
INSTALLATION PROCEDURES .........................................................................10
A. LocationRequirements.............................................................................................................. 10
B. Unpacking/SettingUp ............................................................................................................... 11
C. DryerEnclosureRequirements .................................................................................................. 12
D. FreshAir Requirements ............................................................................................................. 13
E. ExhaustRequirements................................................................................................................ 14
F. ElectricalInformation ................................................................................................................ 18
G. GasInformation......................................................................................................................... 25
H. SteamInformation..................................................................................................................... 28
I. PreparationFor Operation/Start-Up .......................................................................................... 34
J. PreoperationalTests ................................................................................................................... 35
K.Preoperational Instructions ......................................................................................................... 37
L. ShutDown Instructions.............................................................................................................. 38
SECTION IV
SERVICE/PARTS INFORMATION......................................................................39
A.Service ...................................................................................................................................... 39
B. Parts .......................................................................................................................................... 39
SECTION V
WARRANTY INFORMATION ..............................................................................40
A. ReturningWarrantyCard(s) ...................................................................................................... 40
B. Warranty................................................................................................................................... 40
C. ReturningWarranty Part(s) ........................................................................................................ 40

SECTION VI
ROUTINE MAINTENANCE..................................................................................42
A. Cleaning ................................................................................................................................... 42
B. Adjustments .............................................................................................................................. 43
C. Lubrication ............................................................................................................................... 43
SECTION VII
PROCEDURE FOR FUNCTIONAL CHECK OF REPLACEMENT
COMPONENTS .......................................................................................................44
SECTION VIII
REVERSING TIMER SPIN/DWELL ADJUSTMENTS ....................................47
SECTION IX
DATA LABEL INFORMATION.............................................................................48
A. DataLabel................................................................................................................................ 48
SECTION X
BURNER and BASKET (TUMBLER)/LINT CHAMBER MANUAL RESET
HI-LIMIT INSTRUCTIONS...................................................................................50
Gas ................................................................................................................................................ 50
Electricor Steam ............................................................................................................................ 51

3
SECTION I
IMPORTANT INFORMATION
A. RECEIVING and HANDLING
The dryer is shipped in a protective stretch wrap cover with protective cardboard corners and top cover (or
optional box) as a means of preventing damage in transit. Upon delivery, the dryer and/or packaging, and wooden
skid should be visually inspected for shipping damage. If any damage whatsoever is noticed, inspect further
before delivering carrier leaves.
Dryers damaged in shipment:
1. ALL dryers should be inspected upon receipt and before they are signed for.
2. If there is suspected damage or actual damage, the trucker's receipt should be so noted.
3. If the dryer is damaged beyond repair, it should be refused. Those dryers which were not damaged in a
damaged shipment should be accepted, but the number received and the number refused must be noted
on the receipt.
4. If you determine that the dryer was damaged after the trucker has left your location, you should call the
delivering carrier's freight terminal immediately and file a claim. The freight company considers this concealed
damage. This type of freight claim is very difficult to get paid and becomes extremely difficult when more
than a day or two passes after the freight was delivered. It is your responsibility to file freight claims.
Dryer/parts damaged in transit cannot be claimed under warranty.
5. Freight claims are the responsibility of the consignee, and ALL claims must be filed at the receiving end.
ADC assumes no responsibility for freight claims or damages.
6. If you need assistance in handling the situation, please contact theADC Traffic Manager at [phone].
IMPORTANT:The basket (tumbler) section of the dryer must be transported and handled in an
upright position at ALLtimes.

4
B. SAFETY PRECAUTIONS
WARNING:For your safety, the information in this manual must be followed to minimize the risk of
fire or explosion or to prevent property damage, personal injury, or loss of life.
WARNING: The dryer must never be operated with any of the back guards, outer tops, or
service panels removed. PERSONAL INJURY or FIRE COULD RESULT.
1. DO NOT store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other
appliance.
2. Purchaser/user should consult the local gas supplier for proper instructions to be followed in the event the
user smells gas. The instructions should be posted in a prominent location.
3. WHAT TO DO IF YOU SMELL GAS...
a. DO NOT try to light any appliance.
b. DO NOT touch any electrical switch.
c. DO NOT use any phone in your building.
d. Clear the room, building, or area of ALLoccupants.
e. Immediately call your gas supplier from a neighbor's phone. Follow the gas supplier's instructions.
f. If you cannot reach your gas supplier, call the fire department.
4. Installation and service must be performed by a qualified installer, service agency, or gas supplier.
5. Dryer(s) must be exhausted to the outdoors.
6. Although ADC produces a very versatile dryer, there are some articles that, due to fabric composition or
cleaning method, should not be dried in it.
WARNING:Dry only water washed fabrics. DO NOT dry articles spotted or washed in dry
cleaning solvents, a combustible detergent, or "ALL purpose" cleaner.
EXPLOSION COULD RESULT.
WARNING:DO NOT dry rags or articles coated or contaminated with gasoline, kerosene, oil, paint,
or wax.
EXPLOSION COULD RESULT.
WARNING:DO NOT dry mop heads. Contamination by wax or flammable solvents will create a
fire hazard.
WARNING:DO NOT use heat for drying articles that contain plastic, foam, sponge rubber, or
similarly textured rubber materials. Drying in a heated basket (tumbler) may damage
plastics or rubber and also may be a fire hazard.

5
7. A program should be established for the inspection and cleaning of lint in the heating unit area, exhaust
ductwork, and inside the dryer. The frequency of inspection and cleaning can best be determined from
experience at each location.
WARNING:The collection of lint in the burner area and exhaust ductwork can create a potential
fire hazard.
8. For personal safety, the dryer must be electrically grounded in accordance with local codes and/or the
National Electrical Code ANSI/NFPA NO. 70-LATEST EDITION, or in Canada, the Canadian Electrical
Codes Parts 1 & 2 CSA C22.1-1990 or LATEST EDITION.
NOTE:Failure to do so will VOID THE WARRANTY.
9. UNDER NO CIRCUMSTANCES should the dryer door switches, lint door switch, heat safety circuit
ever be disabled.
WARNING: PERSONAL INJURY or FIRE COULD RESULT.
10. This dryer is not to be used in the presence of dry cleaning solvents or fumes.
11. Remove articles from the dryer as soon as the drying cycle has been completed.
WARNING:Articles left in the dryer after the drying and cooling cycles have been completed can
create a fire hazard.
12. DO NOT operate steam dryers with more than 125 PSI (8.6 bars) steam pressure. Excessive steam
pressure can cause damage to the steam coil and/or harm personnel.
13. Replace leaking flexible hoses or other steam fixtures immediately. DO NOT operate the dryer with
leaking flexible hoses. PERSONAL INJURY MAY RESULT.
14. The normal PH level for copper type steam coils must be maintained between a value of 8.5 to 9.5. For
steel type steam coils the PH level must be maintained between a value of 9.5 to 10.5. These limits are set
to limit the acid attack of the steam coils.
IMPORTANT:Coil failure due to improper PH level will VOID THE WARRANTY.
15. READ and FOLLOWALLCAUTIONandDIRECTIONLABELSATTACHEDTOTHEDRYER.
16. For safety, proper operation, and optimum performance, the dryer must not be operated with a load less
than sixty-six percent (66%), 36 pounds (16 kg) of its rated capacity.
WARNING: YOU MUST DISCONNECT and LOCKOUT THE ELECTRIC SUPPLY and
THE GAS SUPPLY or THE STEAM SUPPLY BEFORE ANY COVERS or
GUARDS ARE REMOVED FROM THE MACHINE TO ALLOW ACCESS
FOR CLEANING, ADJUSTING, INSTALLATION, or TESTING OF ANY
EQUIPMENT per OSHA (Occupational Safety and Health Administration)
STANDARDS.

6
SECTION II
SPECIFICATIONS/COMPONENT IDENTIFICATION
A. SPECIFICATIONS
NOTE:ADCreserves the right to make changes in specifications at any time without notice or
obligation.
IMPORTANT:Steam dryers must be provided with clean, dry, regulated 80 PSI ± 10 PSI
(5.52 bars ± 0.68 bars) air supply.
AMPS
WITHOUT HEAT RECLAIMER
WITH
HEAT RECLAIMER
MAXIMUM CAPACITY (DRY WEIGHT) 55 lbs 25 kg
BASKET (TUMBLER) DIAMETER 37" 94 cm
BASKET (TUMBLER) DEPTH 30" 76.2 cm
BASKET (TUMBLER) VOLUME 18.67 cu. ft. 0.528 cu. m.
MOTOR (HORSEPOWER) 3/4 HP 0.56 kw
DOOR OPENING 31-3/8" 79.7 cm
APPROX. WEIGHT (UNCRATED) 585 lbs 265 kg 630 lbs 286 kg
APPROX. WEIGHT (CRATED) 645 lbs 293 kg 690 lbs 313 kg
GAS
AIRFLOW 600 cfm 17 cmm 375 cfm 10.6 cmm
HEAT INPUT 160,000 btu/hr 40,320 kcal/hr 140,000 btu/hr 35,280 kcal/hr
GAS INLET 1/2" 1/2"
VOLTAGE AVAILABLE 120 VOLTS OR230 VOLTS
ELECTRIC
AIRFLOW 600 cfm 17 cmm
OVEN SIZE APPLIED VOLTAGE/PHASE
Kw btu/hr kcal/hr 208/1ø 240/1ø 208/3ø 240/3ø 380/3ø 416/3ø 460/3ø
60 Hz 50 Hz 60 Hz 50 Hz 60 Hz 50 Hz 60 Hz 50 Hz 60 Hz 50 Hz 60 Hz 50 Hz 60 Hz 50 Hz 60 Hz 50 Hz
20 68,260 17,200 103 --- 90 --- --- --- --- --- --- 33 --- --- --- ---
24 81,910 20,640 --- --- --- --- 70 --- 62 62 --- --- --- 36 31 ---
30 102,390 25,800 --- --- --- --- 86 --- 75 75 --- --- --- 44 38 ---
STEAM*†
AIRFLOW 600 cfm 17 cmm
STEAM CONSUMPTION BOILER HP
NORMAL LOAD OPERATING STEAM PRESSURE STEAM SUPPLY STEAM RETURN
144.7 lb/hr 65.7 kg/hr 4.2 125 psi 8.6 bar 1" 1"
Shaded areas are stated in metric equivalents
*Specify Air-Operated Steam Damper system or Electromechanical Steam Damper system when ordering.
†Air-Operated Steam Damper system must be provided with a clean, dry, regulated 80 psi ± 10 psi (5.52 bars ± 0.68 bars).
Air connection is 1/8" N.P.T. Air volume requirement is 0.75 cfh (0.02cmh).

7
Specifications
MLG-55HS
MLE-55
MLS-55
NOTE:ADCreserves the right to make changes in specifications at any time without notice or
obligation.

8
B. COMPONENT IDENTIFICATION
1. Dryer Front View
Illus. No. Description
1Controls
2Control (top access) Door Assembly
3Main Door Assembly
4Lint Compartment Area (lint screen located behind door)
5Data Label and Installation Label (located on the backside of the upper control door).

9
2. Dryer Rear View
Illus. No. Description
1Heating Unit
21/8" Compressed Air Supply Inlet
(located behind the electric service relay box on steam models ONLY)
3* Electric Service Relay Box
4Basket (Tumbler) Bearing Mount Assembly
5Idler Bearing Mount Assembly
6Blower Motor Assembly (Reversing Models ONLY)
7Leveling Leg (rear)
8Basket (Drive) Motor Assembly
9Dryer Exhaust
* Electric service connections for gas and steam models are made in this box.
NOTE:1/8-inch compressed air supply inlet (for steam models only) is located behind the electric
service relay box.

10
SECTION III
INSTALLATION PROCEDURES
Installation should be performed by competent technicians in accordance with local and state codes. In the
absence of these codes, the installation must conform toapplicable American National Standards: ANSI Z223.1-
LATEST EDITION (National Fuel Gas Code) or ANSI/NFPA NO. 70-LATEST EDITION (National Electrical
Code) or in Canada, the installation must conform to applicable Canadian Standards: CAN/CGA-B149.1-M91
(Natural Gas) or CAN/CGA-B149.2-M91 (Liquid Propane [L.P.] Gas) or LATEST EDITION (for General
Installation and Gas Plumbing) or Canadian Electrical Codes Parts 1 & 2 CSA C22.1-1990 or LATEST EDITION
(for Electrical Connections).
A. LOCATION REQUIREMENTS
Before installing the dryer, be sure the location conforms to local codes and ordinances. In the absence of such
codesor ordinancesthe locationmust conform withtheNational FuelGasCodeANSI.Z223.1 LATESTEDITION,
or in Canada, the installation must conform to applicable Canadian Standards: CAN/CGA-B149.1-M91 (Natural
Gas) or CAN/CGA-B149.2-M91 (L.P. Gas) or LATEST EDITION (for General Installation and Gas Plumbing).
1. The dryer must be installed on a sound level floor capable of supporting its weight. Carpeting must be
removed from the floor area that the dryer is to rest on.
IMPORTANT: “The dryer must be installed on noncombustible floors only.”
2. The dryer must not be installed or stored in an area where it will be exposed to water and/or weather.
3. The dryer is for use in noncombustible locations.
4. Provisions for adequate air supply must be provided as noted in this manual (refer to Fresh Air
Requirements in Section D).
5. Clearance provisions must be made from combustible construction as noted in this manual (refer to Dryer
Enclosure Requirements in Section C).
6. Provisions must be made for adequate clearances for servicing and for operation as noted in this manual
(refer to Dryer Enclosure Requirements in Section C).
7. Dryer must be exhausted to the outdoors as noted in this manual (refer to Exhaust Requirements in
Section E).
8. Dryer must be located in an area where correct exhaust venting can be achieved as noted in the manual
(refer to Exhaust Requirements in Section E).
IMPORTANT:Dryer should be located where a minimum amount of exhaust duct will be necessary.

11
B. UNPACKING/SETTING UP
Remove protective shipping material (i.e., plastic wrap, and/or optional shipping box) from dryer.
IMPORTANT:Dryer must be transported and handled in an upright position at ALL times.
The dryer can be moved to its final location while still attached to the skid or with the skid removed. To un-skid
the dryer, locate and remove the four (4) bolts securing the base of the dryer to the wooden skid. Two (2) are at
the rear base (remove the back panel for access), and two (2) are located in the bottom of the lint chamber. To
remove the two (2) bolts located in the lint chamber area, remove the lint door.
With the skid removed, to make it easier to slide the dryer into its final position, slightly lower ALL four (4)
leveling legs, so that the dryer will slide on the legs instead of the base frame.
To increase bearing life and improve efficiency, the dryer should be tilted slightly to the rear.
The basket (tumbler) is supported during shipping by a wooden block. REMOVE THIS BLOCK BEFORE
STARTING THE DRYER.
IMPORTANT: For microprocessor controller (computer) or (computer) models, this wooden
block must be removed before connecting power to the dryer or irreparable
damage to the basket (tumbler) will result.
The lint coops of ALL ML-55 dryers are supported during shipping by a bracket. REMOVE THIS BRACKET
BEFORE STARTING THE DRYER.
1. Leveling Dryer
The dryer is equipped with four (4) leveling legs, one (1) at each corner of the base. Two (2) are located at
the rear of the dryer base, and two (2) are located in the lint chamber (coop). To increase bearing life and
improve efficiency, the dryer should be tilted slightly to the rear.

12
C. DRYER ENCLOSURE REQUIREMENTS
Bulkheads and partitions should be made of noncombustible materials and must be located a minimum of
12-inches (30.48 cm), 18-inches (45.72 cm) or more is recommended for ease of installation, maintenance, and
service, above the dryer outer top, except along the front of the dryer which may be partially closed in if desired.
The clearance between the bulkhead header and the dryer must bea minimum of 4-inches (10.16 cm) and must
not extend more than 4-inches (10.16 cm) to the rear of the front. The bulkhead facing must not be closed in
ALL the way to the top of the dryer. A 1-inch (2.54 cm) clearance is required.
NOTE:Allowances must be made for opening the control door.
Dryers may be positioned sidewall to sidewall. However, a 1/16-inch (1.58 mm) minimum allowance must be
made for opening and closing of the control door and the lint door. It is suggested that the dryer be positioned
about 2 feet (0.61 meters) away from the nearest obstruction for ease of installation, maintenance, and service
(to be measured from the back guard.) Refer to the illustration above for details.
NOTE:Air considerations are important for proper and efficient operation.
IMPORTANT:Even though a minimum of only 12-inches (30.48 cm) is required, 18-inches (45.72
cm) or more is suggested. The additional clearance is advantageous for ease of
installation and service.
IMPORTANT:When fire sprinkler systems are located above the dryers, a minimum of 18-inches
(45.72 cm) above the dryer console (module) is required. Dryers may be positioned
sidewall to sidewall however, a 1/16-inch (1.58 mm) minimum allowance is required
between dryers (or wall) for ease of installation and maintenance. Allowances must be
made for the opening and closings of the control door and the lint door.

13
To compensate for the use of registers or louvers used over the openings, this make-up airmust beincreased by
approximately thirty-three percent (33%). Make-up air openings should not be located in an area directly near
where exhaust vents exit the building.
It is not necessary to have a separate make-up air opening for each dryer. Common make-up air openings are
acceptable. However, they must be set up in such a manner that the make-up air is distributed equally to ALL
the dryers.
EXAMPLE: For a bank of (4) dryers, two (2) unrestricted openings measuring 2 feet by 1-1/4 feet
(0.61 meters by 0.38 meters), 5 square feet (0.47 square meters) is acceptable
Allowances must be made for remote or constricting passageways or where dryers are located at excessive
altitudes or predominantly low pressure areas.
IMPORTANT:Make-up air must be provided from a source free of dry cleaning solvent fumes.
Make-up air that is contaminated by dry cleaning solvent fumes will result in
irreparable damage to the motors and other dryer components.
NOTE:Component failure due to dry cleaning solvent fumes will VOID THE WARRANTY.
D. FRESH AIR REQUIREMENTS
When the dryer is operating, it draws in room air, heats it, passes this air through the basket (tumbler), and
exhausts it out of the building. Therefore, the room airmust be continually replenished from the outdoors. If the
make-up air is inadequate, drying time and drying efficiency will be adversely affected. Ignition problems and sail
switch "fluttering" problems may result, as well as premature motor failure from overheating.
Air supply (make-up air) must be given careful consideration to assure proper performance of each dryer. An
unrestricted source of air is necessary for each dryer. An airflow of 600 cfm (cubic feet per minute) - 17 cmm
(cubic meters per minute) must be supplied to each gas, electric, and steam dryer. As a general rule, an
unrestricted air entrance from the outdoors (atmosphere) of a minimum of 1-1/4 square foot (0.12 square meters)
is required for each dryer.

14
E. EXHAUST REQUIREMENTS
1. General Exhaust Ductwork Information
Exhaust ductwork should be designed and installed by a qualified professional. Improperly sized ductwork
will create excessive back pressure which results in slow drying, increased use of energy, overheating of the
dryer, and shutdown of the burner by the airflow (sail) switches, burner hi-limits, or basket (tumbler) hi-heat
thermostats.
CAUTION:DRYER MUST BE EXHAUSTED TO THE OUTDOORS.
CAUTION:IMPROPERLY SIZED orINSTALLED EXHAUST DUCTWORKCAN
CREATE APOTENTIALFIREHAZARD.
The ductwork should be laid out in such a way that the ductwork travels as directly as possible to the
outdoors with as few turns as possible. Single or independent dryer venting is recommended.
Horizontal Venting:
When single dryer venting is used, the length of ductwork from the dryer to the outside exhaust outlet, must
not exceed15 feet (4.6 meters). The minimum diameter of this ductwork must be at least 8-inches (20.32
cm). In the case of multiple (common) dryer venting, the distance from the last dryer to the outside exhaust
outlet must not exceed15 feet (4.6 meters). The shape of the ductwork is not critical so long as the
minimum cross-sectional area is provided. It is suggested that the use of 90° turnsbe avoided; use 30° and/
or 45° angles instead. The radius of the elbowsshould preferably be 1-1/2 times the diameter of the duct.
Including basket (tumbler)/dryer elbow connections or elbows used for outside protection from the weather,
no more than two (2) elbowsshould be used in the exhaust duct run. If more than two (2) elbows are used,
the cross-sectional area of the ductwork must be increased. ALL ductwork should be smooth inside with
no projections from sheet metal screws or other obstructions, which will collect lint. When adding ducts, the
duct to be added should overlap the duct to which it is to be connected. ALL ductwork jointsmust be taped
to prevent moisture and lint from escaping into the building. Inspection doorsshould be installed at strategic
points in the exhaust ductwork for periodic inspection and cleaning of lint from the ductwork.
Vertical Venting:
When single dryer venting is used, the length of the ductwork from the dryer to the outside exhaust outlet
must not exceed 15 feet (4.6 meters). The minimum diameter of this ductworkmust be at least 8-inches
(20.32 cm). In the case of multiple (common) dryer venting, the distance from the last dryer to the outside
exhaust outlet must not exceed15 feet (4.6 meters). The shape of the ductwork is not critical so long as
the minimum cross-sectional area is provided. It is suggested that the use of 90º turns be avoided; use 30º
and/or 45º angle instead. The radius of the elbows should preferably be 1-1/2 times the diameter of the
duct. ALL ductwork should be smooth inside with no projections from sheet metal screws or other
obstructions, which will collect lint. When adding ducts, the duct to be added should overlap the duct to
which it is to be connected. ALL ductwork jointsmust be taped to prevent moisture and lint from escaping
into the building. Inspection doors should be installed at strategic points in the exhaust ductwork for
periodic inspection and cleaning of lint from the ductwork.
IMPORTANT:Exhaust back pressure measured by a manometer in the exhaust duct must not
exceed 0.3 inches (0.74 mb) of water column (W.C.).
IMPORTANT:Minimum ductwork diameter for horizontal venting is 8-inches (20.32 cm) and for
vertical venting the minimum is 8-inches (20.32 cm).

15
NOTE:When the exhaust ductwork passes through a wall, ceiling, or roof made of combustible
materials, the opening must be 2-inches (5.08 cm) larger than the duct (ALL the way around).
The duct must be centered within this opening.
a. Outside Ductwork Protection
1) To protect the outside end of horizontal ductwork from the weather, a 90° elbow bent downward
should be installed where the exhaust exits the building. If the ductwork travels vertically up
through the roof, it should be protected from the weather by using a 180° turn to point the opening
downward. In either case, allow at least twice the diameter of the duct between the duct opening
and the nearest obstruction.
IMPORTANT:DO NOT use screens, louvers, or caps on the outside opening of the exhaust
ductwork.
2. Single Dryer Venting
Where possible, it is suggested to provide a separate exhaust duct for each dryer. The exhaust duct should
be laid out in such a way that the ductwork travels as directly as possible to the outdoors with as few turns
as possible. It is suggested that the use of 90° turns in the ducting be avoided; use 30° and/or 45° angles
instead. The shape of the exhaust ductwork is not critical so long as the minimum cross section area is
provided.
IMPORTANT:Minimum duct size for a dryer that is vented horizontally is 8-inches (20.32 cm) for a
round duct or an equivalent of 54 square inches (348.4 square centimeters). THE
DUCT SIZE MUST NOT BE REDUCED ANYWHEREDOWNSTREAM
OF THE DRYER.
IMPORTANT:Exhaust back pressure measured by a manometer at each basket (tumbler) exhaust
duct area must not exceed 0.3 inches (0.74 mb) of water column (W.C.).
IMPORTANT:Minimum duct size for a dryer that is vented vertically is 8-inches (20.32 cm) for a
round duct or an equivalent of 54 square inches (348.4 square centimeters). THE
DUCT SIZE MUST NOT BE REDUCED ANYWHEREDOWNSTREAM
OF THE DRYER.

16
IMPORTANT:For extended ductwork runs, the cross section area of the ductwork can only be
increased to an extent. When the ductwork approaches the maximum limits noted in
this manual, a professional heating, venting, and air conditioning (HVAC) firm should
be consulted for proper venting information.
ALL ductwork should be smooth inside with no projections from sheet metal screws or other obstructions,
which will collect lint. When adding ducts, the duct to be added should overlap the duct to which it is to be
connected. ALL ductwork jointsmust be taped to prevent moisture and lint from escaping into the building.
Inspection doors should be installed at strategic points in the exhaust ductwork for periodic inspection and
cleaning of lint from the ductwork.
NOTE:When the exhaust ductwork passes through a wall, ceiling, or roof made of combustible
materials, the opening must be 2-inches (5.08 cm) larger than the duct (ALL the way around).
The duct must be centered within this opening.
a. Outside Ductwork Protection
1) To protect the outside end of horizontal ductwork from the weather, a 90° elbow bent downward
should be installed where the exhaust exits the building. If the ductwork travels vertically up
through the roof, it should be protected from the weather by using a 180° turn to point the opening
downward. In either case, allow at least twice the diameter of the duct between the duct opening
and the nearest obstruction.
IMPORTANT:DO NOT use screens, louvers, or caps on the outside opening of the exhaust
ductwork.