American Dryer Corp. ML-122D User manual

For replacement parts, contact the reseller from which the dryer
was purchased or
American Dryer Corporation
88 Currant Road
Fall River MA 02720-4781
Telephone: [phone] / Fax: [phone]
E-mail: [e-mail]
www.amdry.com
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 death.
Do not store or use gasoline or other flammable
vapor and liquids in the vicinity of this or any
other appliance.
WHAT DO YOU DO IF YOU SMELL GAS
* Do not try to light any appliance.
* Do not touch any electrical switch; do not use
any phone in your building.
* Clear the room, building or area of all
occupants.
* 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.
Installation and service must be performed by a
qualified installer, service agency or the gas
supplier.
AVERTISSEMENT: Assurez-vous de bien
suivre les instructions données dans cette
notice pour réduire au minimum le risque
d’incendie ou d’explosion ou pour éviter tout
dommage matériel, toute blessure ou la mort.
Ne pas entreposer ni utiliser d’essence ni
d’autres vapeurs ou liquides inflammables dans
le voisinage de cet appareil ou de tout autre
appareil.
QUE FAIRE SI VOUS SENTEZ UNE ODEUR
DE GAZ:
* Ne pas tenter d’allumer d’appareil.
* Ne touchez à aucun interrupteur. Ne pas
vous servir des téléphones se trouvant dans
le bâtiment où vous vous trouvez.
* Évacuez la pièce, le bâtiment ou la zone.
* Appelez immédiatement votre fournisseur de
gaz depuis un voisin. Suivez les instructions
du fournisseur.
* Si vous ne pouvez rejoindre le fournisseur
de gaz, appelez le service des incendies.
L’installation et l’entretien doivent être assurés
par un installateur ou un service d’entretien
qualifié ou par le fournisseur de gaz.
020900RF/pb ADC Part No. 113126
ML-122D
(Gas & Steam)
Installation Manual

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.
“IMPORTANT NOTE TO PURCHASER”
Information must be obtained from your local gas supplier on the instructions
to be followed if the user smells gas. These instructions must be posted in a
prominent location near the dryer.
FOR YOUR SAFETY
Do not store or use gasoline or
other flammable vapors or
liquids in the vicinity of this or
any other appliance.
POUR VOTRE SÉCURITÉ
Ne pas entreposer ni utiliser d’essence
ni d’autres vapeurs ou liquides
inflammables dans le voisinage de cet
appareil ou de 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. The illustrations included in this manual may not depict your particular dryer exactly.
Important
For your convenience, log the following information:
DATE OF PURCHASE ________________________________ MODEL NO. __________________________________________
RESELLER’S NAME ________________________________________________________________________________________
Serial Number(s) ________________________________________________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
Replacement parts can be obtained from your reseller or the ADC factory. When ordering replacement parts from the factory,
you can FAX your order to ADC at [phone] or telephone your order directly to the ADC Parts Department at (508)
678-9000. Please specify the dryer model number and serial number in addition to the description and part number, so that
your order is processed accurately and promptly.
ML-122D

IMPORTANT
YOU MUST DISCONNECTAND LOCKOUT THE ELECTRIC SUPPLYAND 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 HealthAdministration) STANDARDS.
WARNING
CHILDREN SHOULD NOT BE ALLOWED TO PLAY ON OR NEAR THE DRYER(S).
CHILDREN SHOULD BE SUPERVISED IF NEAR DRYERS IN OPERATION.
CAUTION
DRYERS SHOULD NEVER BE LEFT UNATTENDEDWHILE IN OPERATION.
FOR YOUR SAFETY
DO NOT DRYMOPHEADS IN THE DRYER.
DO NOT USE DRYER IN THE PRESENCE OF DRY CLEANING FUMES.
WARNING
UNDER NO CIRCUMSTANCES should the door switch, lint drawer switch, or the
heat circuit devices ever be disabled.
“Caution: Label all wires prior to
disconnection when servicing controls. Wiring
errors can cause improper operation.”
«Attention: Lor des opérations d’entretien
des commandes étiqueter tous fils avant
de les déconnecter. Toute erreur de
câblage peut étre une source de danger et
de panne.»

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.
IMPORTANT
PLEASE OBSERVE ALLSAFETY PRECAUTIONS displayed on the equipment and/or
specified in the installation manual included with the dryer.
WARNING
DRYER MUST NEVER BE OPERATED WITHOUT THE LINT FILTER/SCREEN IN
PLACE, EVEN IFAN EXTERNALLINT COLLECTION SYSTEM IS USED.
Dryers must not be installed 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.

Table of Contents
SECTION I
IMPORTANT INFORMATION ............................................................................... 3
A. Receiving and Handling ............................................................................................................... 3
B. Safety Precautions ...................................................................................................................... 4
SECTION II
SPECIFICATIONS/COMPONENT IDENTIFICATION..................................... 6
A. Specifications (Gas and Steam) ................................................................................................... 6
B. Component Identification ............................................................................................................ 8
SECTION III
INSTALLATION PROCEDURES ......................................................................... 10
A. Location Requirements ............................................................................................................. 10
B. Unpacking/Setting Up ............................................................................................................... 11
C. Dryer Enclosure Requirements .................................................................................................. 13
D. FreshAir Supply Requirements ................................................................................................. 14
E. Exhaust Requirements ............................................................................................................... 15
F. Electrical Information ................................................................................................................ 20
G. Gas Information ........................................................................................................................ 23
H. Steam Information .................................................................................................................... 27
I. CompressedAir ....................................................................................................................... 31
J. Preparation For Operation/Start-Up ......................................................................................... 31
K. Preoperational Tests ................................................................................................................. 32
L. Operating Instructions ............................................................................................................... 35
M. Shut Down Instructions ............................................................................................................. 36
SECTION IV
SERVICE/PARTS INFORMATION ...................................................................... 37
A. Service ..................................................................................................................................... 37
B. Parts ........................................................................................................................................ 37
SECTION V
WARRANTY INFORMATION............................................................................... 38
A. Returning Warranty Cards ......................................................................................................... 38
B. Warranty .................................................................................................................................. 38
C. Returning Warranty Parts .......................................................................................................... 38

SECTION VI
ROUTINE MAINTENANCE .................................................................................. 40
A. Cleaning ................................................................................................................................... 40
B. Adjustments ............................................................................................................................. 42
C. Lubrication ............................................................................................................................... 42
SECTION VII
REVERSING TIMER SPIN/DWELL ADJUSTMENTS..................................... 43
SECTION VIII
PROCEDURE FOR FUNCTIONAL CHECK OF REPLACEMENT
COMPONENTS........................................................................................................ 44
SECTION IX
DATA LABEL INFORMATION ............................................................................. 48
A. Data Label ............................................................................................................................... 48
SECTION X
BURNER AND BASKET (TUMBLER)/LINT CHAMBER MANUAL RESET
HI-LIMIT INSTRUCTIONS ................................................................................... 50

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 the ADC Traffic Manager at (508)
678-9000.
IMPORTANT: The dryer must be transported and handled in an upright position at ALL times.

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.

5
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 rubberlike materials. Drying in a heated basket (tumbler) may damage
plastics or rubber and may be a fire hazard.
7. A program should be established for the inspection and cleaning of lint in the burner area, exhaust ductwork,
and area around the back of 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 switch, lint drawer switch, or the heat circuit
devices 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. READ AND FOLLOW ALL CAUTION AND DIRECTION LABELS ATTACHED TO THE
DRYER.
13. For safety, proper operation, and optimum performance, the dryer must not be operated with a load less
than sixty-six percent (66%), 79 lbs (35.83 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
GasSteam
SECTION II
SPECIFICATIONS/COMPONENT IDENTIFICATION
A. SPECIFICATIONS (GAS AND STEAM)
NOTE: Contact manufacturer for electric model specifications.
IMPORTANT: Dryers must be provided with a clean, dry, regulated 80 PSI +/- 10 PSI (5.51 bars
+/- 0.69 bars) air supply.
NOTE: ADCreserves the right to make changes in specifications at any time without notice or
obligation.
MAXIMUM CAPACITY (DRY WEIGHT) 120 lbs 54.43 kg
BASKET (TUMBLER) DIAMETER 44-1/2” 113 cm
BASKET (TUMBLER) DEPTH 42-1/2” 108 cm
BASKET (TUMBLER) MOTOR 1 HP 0.746 kw
BLOWER MOTOR 3 HP 2.238 kw
DOOR OPENING (DIAMETER) 31-3/8” 79.7 cm
BASKET (TUMBLER) VOLUME 38.2 cu. ft. 1.08 cu. m.
DRYERS PER 20’/40’ CONTAINER 3/7
DRYERS PER 45’/48’ TRUCK 9/9
VOLTAGE AVAILABLE 208-460v 3ø 3, 4w 50/60 Hz
HEAT INPUT 415,000 btu/hr 104,580 kcal/hr
APPROX. WEIGHT (UNCRATED) 1,500 lbs 680.4 kg
APPROX. WEIGHT (CRATED) 1,725 lbs 782.5 kg
AIRFLOW 2,800 cfm 79.29 cmm
INLET PIPE SIZE 1” 2.54 cm
COMPRESSED AIR @ 80 PSI (5.51 BARS) 2.5 cfh 0.07 cmh
VOLTAGE AVAILABLE 208-460v 3ø 3, 4w 50/60 Hz
APPROX. WEIGHT (UNCRATED) 1,650 lbs 748.4 kg
APPROX. WEIGHT (CRATED) 1,875 lbs 850.5 kg
HEAT INPUT 13 Bhp
STEAM CONSUMPTION 450 lbs/hr 200.2 kg/hr
AIRFLOW 2,800 cfm 79.29 cmm
INLET PIPE SIZE 1-1/4”
COMPRESSED AIR @ 80 PSI (5.51 BARS) 3.25 cfh 0.09 cmh
Shaded areas are stated in metric equivalents

7
NOTE: ADCreserves the right to make changes in specifications at any time without notice or
obligation.
Specifications
MLG-122 (Gas)
MLS-122 (Steam)

8
B. COMPONENT IDENTIFICATION
1. Dryer Front View
Illus. No. Description
1Microprocessor Control/Keyboard (Touch Pad) Panel Assembly (Controls)
2Control (Top Access) Door Assembly
3Main Door Assembly
4Lint Panel Assembly
5Lint Drawer
6Wire Diagram (Located Behind Control Door)
7Top Console (Module) Assembly

9
2. Dryer Rear View
Illus. No. Description
1Electrical Service Connections
2Top Console
3Heating Unit
4Relay/Wiring Box
5Data Label and Installation Label
6Air Connection

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 NationalStandards: 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
codesorordinances the locationmust conform withtheNationalFuelGasCodeANSI.Z223.1LATESTEDITION,
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. Clearance provisions must be made from combustible construction as noted in this manual (refer to Dryer
Enclosure Requirements in Section C).
5. 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).
6. Provisions for adequate air supply must be provided as noted in this manual (refer to Fresh Air Supply
Requirements in Section D).
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 this manual
(refer to Exhaust Requirements in Section E).
IMPORTANT: Dryer should be located where a minimum amount of exhaust duct will be necessary.
9. The dryer must be installed with a proper exhaust duct connection to the outside.

11
10. The dryer must be installed with provisions for adequate combustion and make-up air supply.
CAUTION: This dryer produces combustible lint and must be exhausted to the outdoors. Every 6
months, inspect the exhaust ducting and remove any lint build up.
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 ALLtimes.
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) lag bolts securing the base of the dryer to the wooden skid. Two (2) are
at the rear base, and two (2) are located in the bottom of the lint chamber. To remove the two (2) lag bolts
located in the lint chamber area, remove the lint drawer and the three (3) Phillips head screws securing the lint
door in place.
1. Leveling Dryer
a. To level the dryer, place 4-inch (10.16 cm) square metal shims (refer to the illustration above) or
other suitable material under the base pads. It is suggested that the dryer be tilted slightly to the rear.

12
2. If more headroom is needed when moving dryer into position, the top console (module) may be removed.
a. To Remove Top Console (Module)
1) Disconnect the ground wire (A) at the rear of dryer.
2) Remove the six (6) sets of nuts and washers (B) holding the console (module) to base. (Located
within control boxes.)
3) Open control door and control panel then disconnect the following:
a) On the right side box, disconnect the 4-pin plug as well as the 4-pin and 2-pin plug located on the
microprocessor controller (computer). Additionally, remove the air connection at the union, and
the two (2) ground wires connected to the dryer base.
b) On the left side box, disconnect the drive and blower motor wires, along with the 2-pin plug and
the three (3) ground wires (two [2] that go to the panel and one [1] that goes to the dryer base).
4) Lift the console (module) off the dryer base (C).
IMPORTANT: The dryer must be transported and handled in an upright position at ALL times.

13
C. DRYER ENCLOSURE REQUIREMENTS
Even though a 30-inch (76.2 cm) clearance is acceptable, it is recommended that the rear of the dryer be
positioned approximately 3 feet (0.91 meters) from nearest obstruction (i.e. wall) for ease of installation,
maintenance, and service. Bulkheads and partitions should be made from noncombustible materials. The
clearance between the bulkhead header and the dryer must be a minimum of 4-inches (10.2 cm) and must not
extend more than 4-inches (10.2 cm) to the rear of the dryer front. The bulkhead facing must not be closed in
ALL the way to the top of the dryer. A 2-inch (5.08 cm) clearance is required.
NOTE: Bulkhead facing should not be installed until after dryer is in place. Ceiling area must be
located a minimum of 12-inches (31 cm) above the top of the dryer.
NOTE: When fire sprinkler systems are located above the dryers, a minimum of 18-inches (46 cm)
above the dryer console (module) is suggested. Dryers may be positioned sidewall to sidewall
however, 1 or 2-inches (2.54 or 5.08 cm) is suggested between dryers (or wall) for ease of
installation and maintenance. Allowances must be made for the opening and closing of the
control and lint doors.

14
D. FRESH AIR SUPPLYREQUIREMENTS
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. The dryer
must be installed with provisions for adequate combustion and make-up air supply.
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 2,800 cfm (cubic feet per minute), (79.29
cmm [cubic meters per minute])must be supplied to each dryer. As a general rule, an unrestricted air entrance
from the outdoors (atmosphere) of a minimum of 3 square feet (0.279 square meters) is required for each dryer.
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 openingsshould 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 six (6) dryers, two (2) unrestricted openings measuring 3 feet by 3 feet (0.91 meters
by 0.91 meters), (18 square feet [1.67 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.

15
NOTE: Component failure due to dry cleaning solvent fumes will VOID THE WARRANTY.
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, over heating of
the dryer, and shutdown of the burner by the airflow (sail) switches, burner hi-limits, or basket (tumbler)
hi-heat thermostats. The dryer must be installed with a proper exhaust duct connection to the outside.
CAUTION: This dryer produces combustible lint and must be exhausted to the outdoors.
CAUTION: DRYER MUST BE EXHAUSTED TO THE OUTDOORS.
CAUTION: IMPROPERLY SIZED OR INSTALLED EXHAUSTDUCTWORKCAN
CREATE APOTENTIALFIREHAZARD.
NOTE: When a dryer is exhausted separately, it is recommendedthat a back draft damper be
installed.
NOTE: When dryers are exhausted into a multiple (common) exhaust line, each dryer must be
supplied with a back draft damper.
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.
When single dryer venting is used, for horizontal ducting the minimum duct size is 16-inches (40.64 cm) in
diameter, the duct run should not have more than one (1) elbow (including outside protection), and must
not exceed 40 feet (12.2 meters) in total length. With single dryer vertical ducting, the minimum duct size
is 18-inches (45.72 cm) in diameter, and the duct run should not have more than three (3) elbows (including
outside protection), and must not exceed 20 feet (6.1 meters) in total length.
In the case of multiple (common) dryer venting, the distance from the last dryer to the outside exhaust duct
outlet must not exceed 20 feet (6.1 meters), and have no more than one (1) elbow (including outside
protection).
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 bends/angles instead. The radius of the
elbows should 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, the limits noted above must be
observed. If more elbows are used, the cross-sectional area of the ductwork must be increased in proportion
to the number of elbows used.
IMPORTANT: When the ductwork approaches the maximum limits noted in this manual, a
professional heating, venting, and air conditioning (HVAC) firm must be consulted for
proper venting information.

16
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 joints must 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 be no less
than 0 and must not exceed 0.3 inches (0.74 mb) of water column (W.C.).
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 the horizontal ductwork from the weather, a 90° elbow bent downward
should be installed where the exhaust exits the building. If the exhaust 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 ductshould
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 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 is 16-inches (40.64 cm) for a round duct or 14-1/2” by
14-1/2” (36.83 cm by 36.83 cm) for a square duct. THE DUCT SIZE MUST
NOT BE REDUCEDANYWHERE DOWNSTREAM OF THE DRYER.