Terry F. Brewer & Associates

619 Mercury Ave., Suite 108

Duncanville, Texas 75137

(972) 298-3525  Fax (972) 298-3521    

 

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Both or Right in Texas

If you Use a SEER 14*, A/C Unit and gas furnace or Heat pump unit .(1)

 

Trade off not allowed for eclectic heat and heat pumps with HSPF less than 7.0, R-8 Duct Work required.(1)

 

(1)Refer to System Lab HDD requirements, LINK.

 

Residential

TABLE 503.3.3.3

MINIMUM DUCT INSULATION a

IECC 2001 Supplement (as required by Texas law)

 

 

 ANNUAL HEATING

DEGREE DAYS

 

INSULATION R-VALUE (h . ft2 . F.)/Btud

Ducts in unconditioned attics or outside building

Ducts in unconditioned basements, crawl spaces, garages, and other unconditioned spacesc

Supply

Return

Supply

Returnb

Below 1,500

8

4

4

0

1,500 to 3,500 (Dallas Area)

8

4

6

2

3,501 to 7,500

8

4

8

2

Above 7,500

11

6

11

2

 

For SI: C= [(F)-32]/1.8, 1 (hft2F)/Btu= 0.176 (m2K)/W, 1 foot= 304.5 mm.

a.Insulation R-values shown are for the insulation as installed and do not include film resistance. The required minimum R-values do not consider water vapor transmission and condensation. Where control of condensation is required, additional insulation, vapor retarders or both shall be provided to limit vapor transmission and condensation. For ducts that are designed to convey both heated and cooled air, duct insulation shall be as required by the most restrictive condition. Where exterior walls are used as plenums, wall insulation shall be as required by the most restrictive condition of this section. 

b. Insulation on return ducts in basements is not required.

c.Unconditioned spaces include ventilated crawl spaces and framed cavities in those floors, wall and ceiling assemblies which separate conditioned space from unconditioned space or outside air, and are uninsulated on the side facing away from the condition space.

d. Insulation resistance measured on a horizontal plane in accordance with ASTM C 518, at a mean temperature of 75F.

Commercial

IECC 2001 Supplement (as required by Texas law)

 

803.2.8 Duct and plenum insulation and sealing. All supply and return air ducts and plenums shall be insulated with a minimum of R-5 insulation when located in unconditioned spaces and with a minimum of R-8 insulation when located outside the building. When located within a building envelope assembly, the duct or plenum shall be separated from the building exterior or unconditioned or exempt spaces by a minimum of R-8 insulation.

Exceptions:

1. When located within equipment.

2. When the design temperature difference between the interior and exterior of the duct or plenum does not exceed 15F (8C).

All 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, or tapes. Tapes and mastics used to seal ductwork shall be listed and labeled in accordance with UL 181A or UL 181B. Duct connections to flanges of air distribution system equipment shall be sealed and mechanically fastened. Unlisted duct tape is not permitted as a sealant on any metal ducts.

*Until Jan. 23 2006 Energy Systems Laboratory R-6 / SEER-12 Tradeoff Letter PDF Link

*After Jan 22, 2006 Energy System laboratory R-6/ Seer 14 Letter PDF Link