subch. IV of ch. SPS 323 Subchapter IV — Delivery Systems
SPS 323.07 SPS 323.07Air distribution systems.
SPS 323.07(1) (1)Sizing. All air distribution systems shall be sized using the velocities and static pressure losses listed in Table 323.07.
TABLE 323.07
DUCT VELOCITIES - See PDF for table PDF
SPS 323.07(2) (2)System sizing. The distribution system, including the evaporator coil, air filters (installed external to the heating unit), ducts, fittings, grilles and registers, shall be sized so that the total external static pressure shall not exceed the static pressure capacity of the fan at the system rated air flow.
SPS 323.07(3) (3)Changes in duct size. Where duct sizes are changed, the slope angle of the transition duct shall not exceed 45°.
SPS 323.07 History History: Cr. Register, November, 1979, No. 287 eff. 6-1-80; correction in (1) made under s. 13.92 (4) (b) 7., Stats., Register December 2011 No. 672.
SPS 323.08 SPS 323.08Ductwork.
SPS 323.08(1) (1)Duct use. Ducts designed for the transmission of air shall be used for no other purpose.
SPS 323.08(2) (2)Interior ducts. All interior ducts shall be constructed in accordance with the following:
SPS 323.08(2)(a) (a) Supply and return air ducts. Supply and return air ducts shall comply with this paragraph except that ducts attached to appliances may be constructed of materials specified in the appliance listing.
SPS 323.08(2)(a)1. 1. Kitchen exhaust ducts and ducts for air exceeding 250° F shall be constructed of sheet metal or lined with sheet metal or constructed of other noncombustible noncorrugated materials.
SPS 323.08(2)(a)2. 2. Ducts connected to furnaces shall be constructed of sheet metal for at least 6 feet from the furnace.
SPS 323.08(2)(a)3. 3. Spaces formed by unlined wood joists, studs or wood I-joists with solid webs may be used as return air ducts. Spaces used as return air ducts shall be cut off from all remaining unused portions of the space by tight-fitting stops of sheet metal or of wood joist material. Bridging shall be removed from the joist space.
SPS 323.08(2)(b) (b) Under-floor plenums. An under-floor space may be used as a plenum in a single dwelling unit in accordance with this section.
SPS 323.08(2)(b)1. 1. The use of the under-floor space shall be limited to buildings not more than 2 stories in height. Except for the floor immediately above the under-floor plenum, supply ducts shall be provided extending from the plenum to registers or other floor levels.
SPS 323.08(2)(b)2. 2. The under-floor spaces shall not be used for storage, shall be cleaned of all loose scrap material and shall be tightly and substantially enclosed.
SPS 323.08(2)(b)3. 3. The enclosing material of the under-floor space, including the side wall insulation and vapor barriers, shall not be more flammable than one-inch (nominal) wood boards (flame spread classification of 200).
SPS 323.08(2)(b)4. 4. Access shall be through an opening in the floor which shall be 18 inches by 24 inches.
SPS 323.08(2)(b)5. 5. The furnace supplying warm air to the under-floor space shall be equipped with an automatic control which will start the air circulating fan when the air in the furnace bonnet reaches a temperature not higher than 150° F. Such control shall be one that cannot be set higher than 150° F.
SPS 323.08(2)(b)6. 6. The furnace supplying warm air to the under-floor space shall be equipped with an approved temperature limit control that will limit outlet air temperature to 200° F.
SPS 323.08(2)(b)7. 7. A noncombustible receptacle shall be placed below each floor opening into the air chamber. The receptacle shall be securely suspended from the floor members and shall be not more than 18 inches below the floor opening. The area of the receptacle shall extend 3 inches beyond the opening on all sides. The perimeter of the receptacle shall have a vertical lip at least one inch high at the open sides if it is at the level of the bottom of the joist, or 3 inches high if the receptacle is suspended.
SPS 323.08(2)(b)8. 8. Floor registers shall be designed for easy removal to permit access for cleaning the receptacles.
SPS 323.08(2)(b)9. 9. Exterior walls and interior stud partitions shall be firestopped at the floor.
SPS 323.08(2)(b)10. 10. Each wall register shall be connected to the air chamber by a register box or boot.
SPS 323.08(2)(b)11. 11. A duct conforming to par. (a) shall extend from the furnace supply outlet at least 6 inches below combustible framing.
SPS 323.08(2)(b)12. 12. The entire ground surface and enclosing exterior walls of the under-floor space shall be covered with a vapor barrier having a vapor permeability rating of one perm or less and a flame spread rating of 200 or less.
SPS 323.08(2)(b)13. 13. Fuel gas lines may not be located within the under-floor space.
SPS 323.08(2)(b)14. 14. A smoke detector shall be placed in the under-floor space. The alarm and low-battery signal of the smoke detector shall be audible in the occupied areas of the dwelling, when actuated.
SPS 323.08(2)(b)15. 15. The exterior walls of the under-floor spaces shall be insulated in accordance with subch. IV of ch. SPS 322. The insulation may not be omitted under the provisions of s. SPS 322.21 or subch. VII of ch. SPS 322.
SPS 323.08 Note Note: Subch. VII of ch. SPS 322 was repealed.
SPS 323.08(2)(b)16. 16. Electrical wiring installed in the plenum shall be in conformance with the Wisconsin Administrative Electrical Code Volume 2.
SPS 323.08(3) (3)Exterior ducts.
SPS 323.08(3)(a)(a) General. Except as provided in par. (b), ducts, which are located in garages, storage attics and similar spaces susceptible to physical damage, shall be constructed of galvanized steel or corrosion-resistive metal.
SPS 323.08(3)(b) (b) Exception. Plastic may be used for bath fan or air-to-air heat exchanger exhaust runs located in spaces outside the dwelling.
SPS 323.08(4) (4)Underground ducts. Ducts, plenums and fittings constructed of metal encased in concrete or ceramic, or other approved materials, may be installed in the ground. Encasement of underground supply air ducts shall be moistureproof.
SPS 323.08 Note Note: See s. SPS 322.42 for insulation requirements for underground ducts.
SPS 323.08(5) (5)Duct construction. Ductwork shall be constructed and installed in accordance with any one of the appropriate following standards:
SPS 323.08(5)(a) (a) ASHRAE Handbook HVAC Systems and Equipment.
SPS 323.08(5)(b) (b) SMACNA, Residential Comfort System Installation Standards Manual
SPS 323.08(5)(c) (c) SMACNA, HVAC Duct Construction Standards-Metal and Flexible.
SPS 323.08(5)(d) (d) SMACNA Fibrous Glass Duct Construction Standards.
SPS 323.08(5)(e) (e) ASHRAE HVAC Applications Handbook.
SPS 323.08(5)(f) (f) NAIMA Fibrous Glass Duct Construction Standards. 
SPS 323.08(6) (6)Thickness. Sheet metal ducts shall conform to the minimum thicknesses listed in Table 323.08-A.
SPS 323.08(7) (7)Duct support. Rigid metal ductwork shall be supported in accordance with Table 323.08-B.
TABLE 323.08-A
DUCT CONSTRUCTION MINIMUM
SHEET METAL GAUGES - See PDF for table PDF
TABLE 323.08-B
DUCT SUPPORT FOR RIGID DUCTS —
16 GAGE MAXIMUM THICKNESS - See PDF for table PDF
1   These hangers are the minimum required to support the weight of the duct off of the joist, stud or similar structure. The band, wire or strap cradling the duct shall not cause any deformation of the duct.
2   “Pair" means that there are 2 vertical legs. One continuous strap can form both vertical legs.
SPS 323.08 Note Note: This table does not prohibit nailing for duct support.
SPS 323.08(8) (8)Joints and seams. All joints and seams shall be securely fastened or locked. Round pipe slip joints shall be lapped at least one inch.
SPS 323.08(9) (9)Vibration control. When used, vibration isolation connectors shall be installed at the joint between the duct and fan or heating equipment. Vibration isolation connectors shall not be used where the air temperature is in excess of 250° F.
SPS 323.08(10) (10)Air passageways of envelope dwellings. The air passageways of envelope type dwellings shall comply with this subsection.
SPS 323.08(10)(a) (a) No heating equipment shall be placed in the air passageways.
SPS 323.08(10)(b) (b) Wood exposed to the air passageways shall be of at least 2 inches nominal thickness.
SPS 323.08(10)(c) (c) Finishes and insulation exposed to the air passageway shall have a flame spread rating of 25 or less and a smoke development rating of 50 or less.
SPS 323.08(10)(d) (d) A vapor barrier shall be installed on the warm side of insulation which forms a part of the thermal envelope of the dwelling. In the roof-ceiling air passageway, a vapor barrier for the insulation of the ceiling may be omitted if heated air is circulated on both sides of the ceiling insulation. The insulation on the roof side of the air passageway shall be provided with a vapor barrier on the warm side of the insulation. Any vapor barrier exposed to circulating air shall have a flame spread rating of 25 or less and a smoke development rating of 50 or less.
SPS 323.08 History History: Cr. Register, November, 1979, No. 287, eff. 6-1-80; cr. (2) (b) and (10), Register, January, 1989, No. 397, eff. 2-1-89; r. and recr. (2) (a), am. (3) and (6), Register, March, 1992, No. 435, eff. 4-1-92; am. (2) (a) 3., (2) (b) 15., (3) (a), and (4), Register, November, 1995, No. 479, eff. 12-1-95; r. and recr. (2) (b) 15. and (5), Register, January, 1999, No. 517, eff. 2-1-99; CR 08-043: r. and recr. (7) and Table 23.08-B Register March 2009 No. 639, eff. 4-1-09; correction in (2) (b) 15. made under s. 13.92 (4) (b) 7., Stats., Register March 2009 No. 639; CR 09-104: am. (4) Register December 2010 No. 660, eff. 1-1-11; correction in (2) (b) 15., (6), (7) made under s. 13.92 (4) (b) 7., Stats., Register December 2011 No. 672.
SPS 323.09 SPS 323.09Dampers, registers and grilles.
SPS 323.09(1) (1)Volume and backdraft dampers.
SPS 323.09(1)(a)(a) Volume duct dampers shall be provided to permit balancing of the system.
SPS 323.09(1)(b) (b) Volume dampers shall be provided with access.
SPS 323.09 Note Note: Acceptable means of access include a manufactured access panel, an air grille used as a cover, a plastic ceiling cap or a damper accessible through an air diffuser or grille.
SPS 323.09(1)(c) (c) Supply ducts may not terminate in a garage unless a backdraft damper is provided.
SPS 323.09(2) (2)Air registers and grilles.
SPS 323.09(2)(a)(a) Supply air registers. All supply air outlets shall be provided with registers or devices which will provide a uniform distribution of air.
SPS 323.09(2)(b) (b) Return air grilles. Return air grilles shall not be located in bathrooms, kitchens, garages, utility spaces or a confined space in which a draft diverter or draft regulator is located. All other habitable spaces shall have permanent openings to a return air grille equal in area to the supply outlet serving those areas. At least one return air opening shall be provided for each floor.
SPS 323.09 History History: Cr. Register, November, 1979, No. 287, eff. 6-1-80; CR 08-043: renum. (1) to (1) (a), cr. (1) (b) Register March 2009 No. 639, eff. 4-1-09.
SPS 323.10 SPS 323.10Piping.
SPS 323.10(1) (1)Pipe sizes and arrangement. All steam and hot water supply and return piping, air-line piping and auxiliary equipment shall be of appropriate sizes, elevations and arrangements to accomplish the calculated results without stress or other detriment.
SPS 323.10 Note Note: The sizes of pipe to be used for mains and risers may be selected from the ASHRAE Guide and Data Book, published by the American Society of Heating, Refrigerating and Air Conditioning Engineers; or the manuals published by the Institute of Boiler and Radiator Manufacturers or the Mechanical Contractors Association of America.
SPS 323.10(2) (2)Expansion and contraction. The piping for the heating system shall be equipped with anchors, expansion swings or joints, supports and similar devices to relieve stress and strain caused by temperature change of the pipe material.
SPS 323.10(3) (3)Pipe insulation. Unguarded steam, hot water supply and return piping shall be covered with insulating material where the pipes pass through occupied areas and the surface temperature exceeds 180° F.
SPS 323.10(4) (4)Steam and hot water pipes. No pipe carrying hot water or steam at a surface temperature exceeding 250° F shall be placed within one inch of any combustible material, pass through a combustible floor, ceiling or partition unless the pipe is protected by a metal sleeve one inch larger in diameter than the pipe or with approved pipe covering.
SPS 323.10(5) (5)Balancing. Balancing cocks shall be provided in each circuit of a hot water distribution system.
SPS 323.10 History History: Cr. Register, November, 1979, No. 287, eff. 6-1-80.
subch. V of ch. SPS 323 Subchapter V — Chimneys and Vents
SPS 323.11 SPS 323.11General requirements.
SPS 323.11(1) (1)Types of chimneys and vents. All heating appliances using solid, liquid or gas fuels shall be vented to the outside by an all-fuel factory-built, masonry chimney or other listed venting system designed to remove the products of combustion.
SPS 323.11(2) (2)Termination.
SPS 323.11(2)(a)(a) Chimneys. All listed factory manufactured chimneys depending on a principle of gravity for the removal of the products of combustion shall terminate at the location specified in the product listing. For masonry chimneys or where termination location is not specified as a part of the listing, the chimney shall extend at least 3 feet above the highest point where the chimney passes through the roof of the building, and at least 2 feet higher than any ridge, peak, wall, or roof within 10 feet horizontally of the chimney.
SPS 323.11(2)(b) (b) Vents. Gas and oil appliance vents shall terminate in locations specified in their listings.
SPS 323.11(3) (3)Sizing. Vents for new or replacement equipment shall be sized to adequately exhaust combustion products from the dwelling.
SPS 323.11 Note Note: The department recommends vent sizing in accordance with NFPA 54, National Fuel Gas Code or its appendix.
SPS 323.11 History History: Cr. Register, November, 1979, No. 287, eff. 6-1-80; renum. (intro) to (2) to be (1) to (3) and am. (1), Register, February, 1985, No. 350, eff. 3-1-85; r. (3), Register, January, 1989, No. 397, eff. 2-1-89; am. (2), Register, March, 1992, No. 435, eff. 4-1-92; cr. (3), Register, November, 1995, No. 479, eff. 12-1-95.
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Published under s. 35.93, Stats. Updated on the first day of each month. Entire code is always current. The Register date on each page is the date the chapter was last published.