Ohio Admin. Code 4101:8-16-01 - Duct systems
SECTION
1601
1601.1
Duct
design.
Duct systems serving heating,
cooling and ventilation equipment shall be installed in accordance with the
provisions of this section and ACCA Manual D, the appliance manufacturer's
installation instructions or other approved methods.
1601.1.1
Above-ground duct systems.
Above-ground duct systems shall conform to the
following:
1.
Equipment connected to duct systems shall be designed to
limit discharge air temperature to not greater than 250°F
(121°C).
2.
Factory-made ducts shall be listed and labeled in
accordance with UL 181 and installed in accordance with the manufacturer's
instructions.
3.
Fibrous glass duct construction shall conform to the
SMACNA Fibrous Glass Duct Construction Standards or NAIMA Fibrous Glass Duct
Construction Standards.
4.
Field-fabricated and shop-fabricated metal and flexible
duct constructions shall conform to the SMACNA HVAC Duct Construction
Standards-Metal and Flexible except as allowed by Table M1601.1.1. Galvanized
steel shall conform to ASTM A653.
5.
The use of gypsum
products to construct return air ducts or plenums is permitted, provided that
the air temperature does not exceed 125°F (52°C) and exposed surfaces
are not subject to condensation.
6.
Duct systems shall
be constructed of materials having a flame spread index of not greater than
200.
7.
Stud wall cavities and the spaces between solid floor
joists to be used as air plenums shall comply with the following
conditions:
7.1.
These cavities or spaces shall not be used as a plenum for
supply air.
7.2.
These cavities or spaces shall not be part of a
required fire-resistance-rated assembly.
7.3.
Stud wall
cavities shall not convey air from more than one floor level.
7.4.
Stud wall
cavities and joist-space plenums shall be isolated from adjacent concealed
spaces by tight-fitting fireblocking in accordance with Section
602.8.
7.5.
Stud wall cavities in the outside walls of building
envelope assemblies shall not be utilized as air
plenums.
8.
Volume dampers, equipment and other means of supply,
return and exhaust air adjustment used in system balancing shall be provided
with access.
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a.
1601.1.2
Underground duct systems.
Underground duct systems shall be constructed of approved
concrete, clay, metal or plastic. The maximum design temperature for systems
utilizing plastic duct and fittings shall be 150°F (66°C). Metal ducts
shall be protected from corrosion in an approved manner or shall be completely
encased in concrete not less than 2 inches (51 mm) thick. Nonmetallic ducts
shall be installed in accordance with the manufacturer's instructions. Plastic
pipe and fitting materials shall conform to cell classification 12454-B of ASTM
D1248 or ASTM D1784 and external loading properties of ASTM D2412. Ducts shall
slope to a drainage point that has access. Ducts shall be sealed, secured and
tested prior to encasing the ducts in concrete or direct burial. Duct tightness
shall be verified as required by Section 1103.3. Metallic ducts having an
approved protective coating and nonmetallic ducts shall be installed in
accordance with the manufacturer's instructions.
1601.2
Vibration isolators.
Vibration isolators installed between mechanical equipment
and metal ducts shall be fabricated from approved materials and shall not
exceed 10 inches (254 mm) in length.
1601.3
Duct
insulation materials.
Duct insulation
materials shall conform to the following requirements:
1.
Duct coverings and
linings, including adhesives where used, shall have a flame spread index not
higher than 25, and a smoke-developed index not over 50 when tested in
accordance with ASTM E84 or UL 723, using the specimen preparation and mounting
procedures of ASTM E2231.
1.
The flame spread
index is not greater than 25 and the smoke-developed index is not greater than
450 at the specified installed thickness.
2.
The foam plastic
is protected in accordance with the ignition barrier requirements of Sections
316.5.3 and 316.5.4.
3.
The foam plastic complies with the requirements of
Section 316.
2.
Duct coverings and linings shall not flame, glow,
smolder or smoke when tested in accordance with ASTM C411 at the temperature to
which they are exposed in service. The test temperature shall not fall below
250°F (121°C). Coverings and linings shall be listed and
labeled.
3.
External reflective duct insulation shall be legibly
printed or identified at intervals not greater than 36 inches (914 mm) with the
name of the manufacturer, the product R-value at the specified installed
thickness and the flame spread and smoke-developed indices. The installed
thickness of the external duct insulation shall include the enclosed air
space(s). The product R-value for external reflective duct insulation shall be
determined in accordance with ASTM C1668.
4.
External duct
insulation and factory-insulated flexible ducts shall be legibly printed or
identified at intervals not longer than 36 inches (914 mm) with the name of the
manufacturer, the thermal resistance R-value at the specified installed
thickness and the flame spread and smoke-developed indices of the composite
materials. Spray polyurethane foam manufacturers shall provide the same product
information and properties, at the nominal installed thickness, to the customer
in writing at the time of foam application. Nonreflective duct insulation
product R-values shall be based on insulation only, excluding air films, vapor
retarders or other duct components, and shall be based on tested C-values at
75°F (24°C) mean temperature at the installed thickness, in accordance
with recognized industry procedures. The installed thickness of duct insulation
used to determine its R-value shall be determined as follows:
4.1.
For duct board,
duct liner and factory-made rigid ducts not normally subjected to compression,
the nominal insulation thickness shall be used.
4.2.
For ductwrap,
the installed thickness shall be assumed to be 75 percent (25-percent
compression) of nominal thickness.
4.3.
For factory-made
flexible air ducts, the installed thickness shall be determined by dividing the
difference between the actual outside diameter and nominal inside diameter by
two.
4.4.
For spray polyurethane foam, the aged R-value per inch
measured in accordance with recognized industry standards shall be provided to
the customer in writing at the time of foam application. In addition, the total
R-value for the nominal application thickness shall be provided.
1601.4
Installation.
Duct installation shall comply with Sections 1601.4.1
through 1601.4.10.
1601.4.1
Joints,
seams and connections.
Longitudinal and
transverse joints, seams and connections in metallic and nonmetallic ducts
shall be constructed as specified in SMACNA HVAC Duct Construction
Standards-Metal and Flexible and NAIMA Fibrous Glass Duct Construction
Standards. Joints, longitudinal and transverse seams, and connections in
ductwork shall be securely fastened and sealed with welds, gaskets, mastics
(adhesives), mastic-plus-embedded-fabric systems, liquid sealants or tapes.
Tapes and mastics used to seal fibrous glass ductwork shall be listed and
labeled in accordance with UL 181A and shall be marked "181A-P" for
pressure-sensitive tape, "181 A-M" for mastic or "181 A-H" for heat-sensitive
tape.
1.
Spray polyurethane
foam shall be permitted to be applied without additional joint
seals.
2.
Where a duct connection is made that is partially
without access, three screws or rivets shall be equally spaced on the exposed
portion of the joint so as to prevent a hinge effect.
3.
For ducts having a
static pressure classification of less than 2 inches of water column (500 Pa),
additional closure systems shall not be required for continuously welded joints
and seams and locking-type joints and seams. This exception shall not apply to
snap-lock and button-lock type joints and seams that are located outside of
conditioned spaces.
1601.4.2
Duct
lap.
Crimp joints for round and oval metal
ducts shall be lapped not less than 1 inch (25 mm) and the male end of the duct
shall extend into the adjoining duct in the direction of
airflow.
1601.4.3
Plastic duct joints.
Joints between plastic ducts and plastic fittings shall be
made in accordance with the manufacturer's installation
instructions.
1601.4.4
Support.
Factory-made ducts listed in accordance with UL 181 shall be
supported in accordance with the manufacturer's installation instructions.
Field- and shop-fabricated fibrous glass ducts shall be supported in accordance
with the SMACNA Fibrous Glass Duct Construction Standards or the NAIMA Fibrous
Glass Duct Construction Standards. Field- and shop-fabricated metal and
flexible ducts shall be supported in accordance with the SMACNA HVAC Duct
Construction Standards- Metal and Flexible.
1601.4.5
Fireblocking.
Duct
installations shall be fireblocked in accordance with Section
602.8.
1601.4.6
Duct insulation.
Duct
insulation shall be installed in accordance with the following
requirements:
1.
A vapor retarder having a permeance of not greater than 0.05
perm [ 2.87 ng/(s * m2 * Pa)] in accordance with
ASTM E96, or aluminum foil with a thickness of not less than 2 mils ( 0.05 mm),
shall be installed on the exterior of insulation on cooling supply ducts that
pass through unconditioned spaces conducive to condensation except where the
insulation is spray polyurethane foam with a water vapor permeance of not
greater than 3 perms per inch [1722 ng/(s * m2 *
Pa)] at the installed thickness.
2.
Outdoor duct
systems shall be protected against the elements.
3.
Duct coverings
shall not penetrate a fireblocked wall or floor.
1601.4.7
Factory-made air ducts.
Factory-made air ducts shall not be installed in or on the
ground, in tile or metal pipe, or within masonry or concrete.
1601.4.8
Duct
separation.
Ducts shall be installed with
not less than 4 inches (102 mm) separation from earth except where they meet
the requirements of Section 1601.1.2.
1601.4.9
Ducts
located in garages.
Ducts in garages shall
comply with the requirements of Section 302.5.2.
1601.4.10
Flood
hazard areas.
In flood hazard areas as
established by Table 301.2(1), duct systems shall be located or installed in
accordance with Section 322.1.6.
1601.5
Under-floor plenums.
Under-floor plenums shall be prohibited in new structures.
Modification or repairs to under-floor plenums in existing structures shall
conform to the requirements of this section.
1601.5.1
General.
The space
shall be cleaned of loose combustible materials and scrap, and shall be tightly
enclosed. The ground surface of the space shall be covered with a moisture
barrier having a thickness of not less than 4 mils ( 0.1 mm). Plumbing waste
cleanouts shall not be located within the space.
1601.5.2
Materials.
The under-floor space, including the sidewall insulation,
shall be formed by materials having flame spread index values not greater than
200 when tested in accordance with ASTM E84 or UL 723.
1601.5.3
Furnace connections.
A
duct shall extend from the furnace supply outlet to not less than 6 inches (152
mm) below the combustible framing. This duct shall comply with the provisions
of Section 1601.1. A noncombustible receptacle shall be installed below any
floor opening into the plenum in accordance with the following
requirements:
1.
The receptacle shall be securely suspended from the floor
members and shall be not more than 18 inches (457 mm) below the floor
opening.
2.
The area of the receptacle shall extend 3 inches (76
mm) beyond the opening on all sides.
3.
The perimeter of
the receptacle shall have a vertical lip not less than 1 inch (25 mm) in height
at the open sides.
1601.5.4
Access.
Access to an
under-floor plenum shall be provided through an opening in the floor with
minimum dimensions of 18 inches by 24 inches (457 mm by 610
mm).
1601.5.5
Furnace controls.
The
furnace shall be equipped with an automatic control that will start the
air-circulating fan when the air in the furnace bonnet reaches a temperature
not higher than 150°F (66°C). The furnace shall additionally be
equipped with an approved automatic control that limits the outlet air
temperature to 200°F (93°C).
1601.6
Independent garage HVAC systems.
Furnaces and air-handling systems that supply air to living
spaces shall not supply air to or return air from a garage.
SECTION 1602
1602.1
Outdoor
air openings.
Outdoor intake openings
shall be located in accordance with Section 303.5.1. Opening protection shall
be in accordance with Section 303.6
1602.2
Return
air openings.
Return air openings for
heating, ventilation and air-conditioning systems shall comply with all of the
following:
1.
Openings shall not be located less than 10 feet (3048 mm)
measured in any direction from an open combustion chamber or draft hood of
another appliance located in the same room or space.
2.
The amount of
return air taken from any room or space shall be not greater than the flow rate
of supply air delivered to such room or space.
3.
Return and
transfer openings shall be sized in accordance with the appliance or equipment
manufacturer's installation instructions, Manual D or the design of the
registered design professional.
4.
Return air shall
not be taken from a closet, bathroom, toilet room, kitchen, garage, mechanical
room, boiler room, furnace room or unconditioned attic.
1.
Taking return air
from a kitchen is not prohibited where such return air openings serve the
kitchen only, and are located not less than 10 feet (3048 mm) from the cooking
appliances.
2.
Dedicated forced-air systems serving only the garage
shall not be prohibited from obtaining return air from the
garage.
5.
For other than dedicated HVAC systems, return air shall
not be taken from indoor swimming pool enclosures and associated deck areas
except where the air in such spaces is dehumidified,
6.
Taking return air
from an unconditioned crawl space shall not be accomplished through a direct
connection to the return side of a forced-air furnace. Transfer openings in the
crawl space enclosure shall not be prohibited.
7.
Return air from
one dwelling unit shall not be discharged into another dwelling unit.
Replaces: 4101:8-16-01
Notes
Promulgated Under: 119.03
Statutory Authority: 3781.10(A)(1)
Rule Amplifies: 3781.01, 4740.14, 3791.04, 3781.11, 3781.10, 3781.06
Prior Effective Dates: 01/01/2013
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