American Dryer Corp. ML-78 Phase 7 (DSI) User manual

ADC Part No. 113029
For replacement parts, contact the distributor from which the dryer
was purchased or
American Dryer Corporation
88 urrant Road
Fall River MA 02720-4781
Telephone: [phone] / Fax: [phone]
E-mail: [e-mail]
010998JEV/tf
WARNING: For your safety the
information in this manual must be
followed to minimize the risk of fire or
explosion or to prevent property dama e,
personal injury or death.
Do not store or use asoline 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 li ht any appliance.
* Do not touch any electrical switch; do not use
any phone in your buildin .
* Clear the room, buildin or area of all
occupants.
* Immediately call your as supplier from a
nei hbor's phone. Follow the as supplier's
instructions.
* If you cannot reach your as supplier, call the
fire department.
Installation and service must be performed by a
qualified installer, service a ency or the as
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
domma e matériel, toute blessure ou la mort.
Ne pas entreposer ni utiliser dessence ni
dautres vapeurs ou liquides inflammables dans
le voisina e 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
az depuis un voisin. Suivez les instructions
du fournisseur.
* Si vous ne pouvez rejoindre le fournisseur
de az, 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 az.
ML-78
Installation Manual
(Gas/Electric/Steam)

Retain This Manual In A Safe Place For Future Reference
Replacement parts can be obtained from your distributor or the ADC factory. When ordering replacement parts from the
factory, you can FAX your order to ADC at (508 678-9447 or telephone your orders 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.
DATE OF PURCHASE MODEL NO.
DISTRIBUTORS NAME
Serial Number(s)
ML-78
IMPORTANT NOTE TO PURCHASER
Information must be obtained from your local as supplier on the instructions
to be followed if the user smells as. These instructions must be posted in a
prominent location near the dryer.
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 PRECA TIONS displayed on the equipment or specified in the installation/operator's manual
included with the dryer.
The following FOR YO R SAFETY caution must be posted near the dryer in a prominent location.
FOR YOUR SAFETY
Do not store or use asoline 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 voisina e 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.
Important
For your convenience, log the following information:

IMPORTANT
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, ADJUST-
ING, INSTALLATION, or TESTING OF ANY E UIPMENT per OSHA (Occupational
Safety and Health Administration) STANDARDS.
CHILDREN SHOULD NOT BE ALLOWED TO PLAY ON OR NEAR THE DRYER(S).
WARNING
CHILDREN SHOULD BE SUPERVISED IF NEAR DRYERS IN OPERATION.
DRYERS SHOULD NE ER BE LEFT UNATTENDED WHILE IN OPERATION.
CAUTION
FOR YOUR SAFETY
DO NOT DRY MOP HEADS IN THE DRYER.
DO NOT USE DRYER IN THE PRESENCE OF DRY CLEANING FUMES.
WARNING
UNDER NO CIRCUMSTANCES should the door 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 ALL SAFETY PRECAUTIONS displayed on the equipment and/or
specified in the installation and operator's manual included with the dryer.
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.
DRYER MUST NEVER BE OPERATED WITHOUT THE LINT FILTER/SCREEN IN
PLACE, EVEN IF AN EXTERNAL LINT COLLECTION SYSTEM IS USED.
WARNING

Table of Contents
SECTION I
IMPORTANT INFORMATION ............................................................................... 3
A. Receivin and Handlin ............................................................................................................... 3
B. Safety Precautions ....................................................................................................................... 4
SECTION II
SPECIFICATIONS and DIMENSIONS ................................................................. 6
A. Specifications .............................................................................................................................. 6
B. Component Identification ............................................................................................................. 8
SECTION III
INSTALLATION REQUIREMENTS .................................................................... 10
A. Location Requirements .............................................................................................................. 10
B. Unpackin /Settin Up ............................................................................................................... 11
C. Dryer Enclosure requirements .................................................................................................... 12
D. Fresh Air Supply ....................................................................................................................... 13
E. Exhaust Requirements ............................................................................................................... 15
F. Electrical Information ................................................................................................................ 19
G. Gas Information ........................................................................................................................ 26
H. Steam Information ..................................................................................................................... 30
I. Preparation For Operation/Start-up .......................................................................................... 35
J. Preoperational Tests .................................................................................................................. 36
K. Preoperational Instructions ........................................................................................................ 38
L. Shut Down Instructions .............................................................................................................. 39
SECTION IV
SERVICE/PARTS INFORMATION ...................................................................... 40
A. Service ..................................................................................................................................... 40
B. Parts ......................................................................................................................................... 40

SECTION V
WARRANTY INFORMATION .............................................................................. 41
A. Returnin Warranty Card(s) ...................................................................................................... 41
B. Parts ......................................................................................................................................... 41
C. Returnin Warranty Card(s) ...................................................................................................... 41
SECTION VI
ROUTINE MAINTENANCE .................................................................................. 43
A. Cleanin ................................................................................................................................... 43
B. Adjustments .............................................................................................................................. 44
SECTION VII
REVERSING TIMER SPIN/DWELL AD USTMENTS ....................................45
SECTION VIII
DATA LABEL LOCATION/INFORMATION ......................................................46
SECTION IX
PROCEDURE FOR FUNCTIONAL CHECK OF REPLACEMENT
COMPONENTS ........................................................................................................48

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. f 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
deliveringcarrier's freightterminal immediatelyand filea claim. Thefreight companyconsiders thisconcealed
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 ALL occupants.
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 machine, 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
COULDRESULT.
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 solvent 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 also may be a fire hazard.

5
7. A program should be established for the inspection and cleaning of lint in the burner area, exhaust
duct work, 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 duct work can create a potential
fire hazard.
8. For personal safety, the dryer must be electrically grounded in accordance with local codes
and/or the NAT ONAL ELECTR C CODE ANS /NFPA NO. 70-LATEST ED T ON.
NOTE: Failure to do so will VOID THE WARRANTY.
9. UNDER NO CIRCUMSTANCES should the dryer door switches, lint drawer switch, or 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 dryin and coolin cycles have been complete can
create a fire hazard.
12. READ and FOLLOW ALL CAUTION and DIRECTION LABELS ATTACHED TO THE DRYER.
WARNING: YOU MUST DISCONNECT nd LOCKOUT THE ELECTRIC SUPPLY nd
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
IMPORTANT: Steam dryers must be provided with a clean, dry, re ulated 80 PSI (+/- 10 PSI)
air supply.
NOTE:ADC reserves the ri ht to make chan es in specifications at any time, without notice or
obli ation.
Gas
Steam Electric
SECTION II
SPECIFICATIONS/COMPONENT IDENTIFICATION
A. SPECIFICATIONS
B ASKET (T UMBLER ) D IAMETER 44-1/2"
113 cm
B ASKET (T UMBLER ) D EPTH 24-7/8"
63.2 cm
B ASKET (T UMBLER ) M OTOR 1 HP *.746 kw
D OOR O PENING (D IAMETER ) 31-3/8" 79.7 cm
B ASKET (T UMBLER ) V OLUME 22.4 cu. ft.
.634 cu.m.
D RYERS P ER 20’/4 0’’ C ONTAINER 10/20
D
RYERS P ER 45’/48’T RUCK 24/24
V
OLTAGE A VAILABLE 120 / 208 / 240 / 480v / 1, 3ø/ 50/60Hz
A
PPROX . W EIGHT ( UNCRATED )895lbs. 407 kg
A PPROX . W EIGHT ( CRATED )950lbs. 432 kg
H EAT I NPUT 204,000 btu/hr
51,408 kcal/hr
A IRFLOW 1,200 cfm
33.98 cmm
Inlet Pipe Size 3/4" ** 1.91 cm
V OLTAGE A VAILABLE 120 / 208 / 240 / 480v / 1, 3ø/ 50/60Hz
A
PPROX . W EIGHT ( UNCRATED )895lbs.
407 kg
A PPROX . W EIGHT ( CRATED )950lbs.
432 kg
A IRFLOW 1,200 cfm
33.98 cmm
V OLTAGE A VAILABLE 120 / 208 / 240 / 480v / 1, 3ø/ 50/60Hz
A
PPROX . W EIGHT ( UNCRATED )980lbs 445 kg
A PPROX . W EIGHT ( CRATED )1,130lbs. 514 kg
A IRFLOW 1,200 cfm
33.98 cmm
C OMPRESSED A IR V OLUME .75 cfh
.02 cmh
C OMPRESSED A IR C ONNECTION 1/8" F.P.T. .318 cm
S TEAM C OMSUMPTION
B OILER HP
N
ORMAL L OAD
238.7 lbs/hr
108.3 kg/hr
7
O
PERATING S TEAM P RESSURE S TEAM S UPPLY S TEAM R ETURN
125 psi max
8.6 bar
1"
2.54 cm
1"
2.54 cm
Shaded areas are stated in metric equivalents.
*
For non-reversing models.
**
A minimum of 3/4" pipe must be supplied to the gas inlet for each dryer.

7
Specifications*
MLG-78 (Gas)
MLS-78 (Steam)
NOTE:ADC reserves the ri ht to make chan es in specifications at any time, without notice or
obli ation.
*Specifications for the MLS-78 (steam model) were not available at time of printing...for information
contact the factory.

8
B. COMPONENT IDENTIFICATION
1. Dryer Front View
llus. No. Description
1 Controls
2 Control (top access) Door Assembly
3 Main Door Assembly
4 Lint Compartment Area (lint screen located behind door)
5 Data Label and nstallation Label (located behind control [service] door)

9
2. Dryer Rear View
Illus. No. Description
1 Heating Unit
2 1/8" Compressed Air Supply Inlet
(behind Electric Service Relay Box for Steam Models ONLY)
3* Electric Service Relay Box
4 Tumbler Bearing Mount Assembly
5 Idler Bearing Mount Assembly
6 Basket (Drive) Motor Assembly (for Reversing Models ONLY)
7 Blower Motor Assembly
8 Dryer Exhaust
* Electric service connections for Gas Models and Steam Models are made in this 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 to applicable American National Standards: National
Fuel Gas CodeANSI.Z223.1-LATEST EDITION and/or National Electric Code ANSI/NFPA NO. 70-LATEST
EDITION.
A. LOCATION REQUIREMENTS
Before installing the dryer, be sure the location conforms to local codes and ordinances. In the absence of such
codes or ordinances the location must conform with the National Fuel Gas Code ANSI.Z223.1-LATEST
EDITION.
1. The dryer must be installed on a sound level floor capable of supporting its weight. It is recommended that
carpeting be removed from the floor area that the dryer is to rest on.
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 FreshAir Supply 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 (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.
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 (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-78 dryers are supported during shipping by a bracket. REMOVE THIS
BRACKET BEFORE STARTING THE DRYER.

12
NOTE: Allowances must be made for opening the control door.
Dryers may positioned side wall to side wall. However, a 1/16" 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 two (2) feet
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.
C. DRYER ENCLOSURE REQUIREMENTS
Bulkheads and partitions should be made of noncombustible materials and must be located a minimum of
twelve (12) inches (18-inches 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 be a minimum of four (4) inches and must not extend more
than four (4) inches to the rear of the front. The bulkhead facing must not be closed in all the way to the top of
the dryer. A one (1) inch clearance is required.

13
IMPORTANT: Even though a minimum of only 12-inches is required, 18-inches 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 above the dryer console (module) is required. Dryers may be
positioned side wall to side wall however, a 1/16" 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.
D. FRESH AIR SUPPLY
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 air must 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 air flow of 1,200 cfm (cubic feet per minute) must be
supplied to each gas and electric dryer and 1,350 cfm (cubic feet per minute) must be supplied to each steam
dryer. As a general rule, an unrestricted air entrance from the outdoors (atmosphere) of a minimum of 1-1/2
square feet is required for each dryer.

14
To compensate for the use of registers or louvers used over the openings, this make-up air must be increased 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 four (4) dryers, two (2) unrestricted openings measuring 2 feet by 1-1/2 feet
(6 square feet) 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 solvents
fumes. Make-up air that is contaminated by dry cleaning solvent fumes will
result in irreparable damage the motors and other dryer components.
NOTE: Component failure due to dry cleaning solvent fumes will VOID THE WARRANTY.

15
E. EXHAUST REQUIREMENTS
1. General Exhaust Duct Work Information
Exhaust duct work should be designed and installed by a qualified professional. Improperly sized duct
work 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 BEEXHAUSTEDTOTHE OUTDOORS.
CAUTION: IMPROPERLYSIZED ORINSTALLED EXHAUSTDUCTWORK CAN
CREATEAPOTENTIALFIREHAZARD.
The duct work should be laid out in such a way that the duct work travels as directly as possible to the out-
doors with as few turns as possible. Single or independent dryer venting is recommended.
HorizontalVenting:
When single drying venting is used the length of duct work from the dryer to the outside exhaust outlet
should not exceed fifteen (15) feet. The minimum diameter of this duct work must be at least 10-inches.
In the case of multiple (common) dryer venting, the distance from the last dryer to the outside exhaust outlet
should not exceed (15) feet. The shape of the duct work is not critical so long as the minimum cross-
sectional area is provided. It is suggested that the use of 90°turns be avoided; use 30°and/or 45°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, no more
than two (2) elbows should be used in the exhaust duct run. If more than two (2) elbows are used, the cross
sectional area of the duct work must be increased. ALL duct work 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 duct work joints must be taped to
prevent moisture and lint from escaping into the building. Inspection door should be installed at strategic
points in the exhaust duct work for periodic inspection and clean-out of lint from the duct work.
Vertical Venting:
When single dryer venting is used the length of the duct work from the dryer to the outside exhaust outlet
should not exceed twenty (20) feet. The minimum diameter of this duct work must be at least 12- inches.
In the case of multiple (common) dryer venting, the distance from the last dryer to the outside exhaust outlet
should not exceed twenty (20) feet. The shape of the duct work is not so critical so long as the minimum
cross sectional area is provided. It is suggested that the use of 90ºturns be avoided; use 30ºand/or 45ºbends
instead. The radius of the elbows should preferably be 1-1/2 times the diameter of the duct. ALL duct
work 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.
ALLduct work joints mustbetaped to prevent moisture and lint from escaping into the building. Inspection
door should be installed at strategic points in the exhaust duct work for periodic inspection and clean-out of
lint from the duct work.
IMPORTANT: Exhaust back pressure measured byamanometerintheexhaustduct should
notexceed0.3inches of water column.

16
IMPORTANT: Minimum duct work diameter for horizontal venting is 10-inches and for vertical
venting the minimum is 12-inches.
NOTE: Where the exhaust duct work passes through a wall, ceiling, or roof made of combustible
materials, the opening must be 2-inches larger (all the way around) than the duct. The
duct must be centered within this opening.
a. Outside Duct Work Protection
1) To protect the outside end of horizontal duct work from the weather, a 90°elbow bent downward
should be installed where the exhaust exits the building. If the duct work 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 or caps on the outside of opening of exhaust duct work.
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 duct work 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 duct work 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 10-inches for a
round duct or an equivalent of 80 square inches. THE DUCT SIZE MUST
NOT BE REDUCED ANYWHERE DOWN STREAM OF THE DRYER.
IMPORTANT: Exhaust back pressure measured by a manometer at each basket (tumbler)
exhaust duct area should not exceed 0.3 inches of water column.