§ 29.04.260. Section 704 amended.

Section 704 of the Guidelines for Solar Energy Installations, 1984 Edition, is hereby amended to read as follows:

"Duct Insulation. The air-distribution system ducts shall be insulated to a minimum of R-6, using material having a perm rating not exceeding 0.5 perm. All joints shall be sealed with an appropriate sealer. All duct insulation shall be in accordance with Table 704."

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"Table No. 704 INSULATION OF DUCTS

Duct Location	Insulation Types Mechanically Cooled	Insulation Types Heating Only
On Roof, On Exterior of Building	C, V* and W	B and W
Attics, Garages and Crawl Space	A and V*	A
In Walls**, Within Floor Ceiling Spaces**	A and V*	A
Within the Conditioned Space or in Basements; Return Ducts and Plenums	None Required	None Required
Cement Slab or Within Ground	None Required	None Required

 

NOTE: Where ducts are used for both heating and cooling, the minimum insulation shall be as required for the most restrictive condition. These requirements based on 4501 to 8000 D.D.

*

Vapor barriers shall be installed on conditioned air supply ducts in spaces vented to the outside in geographic areas where the average July, August and September mean dew point temperature exceeds 60°F.

**

Insulation may be omitted on that portion of a duct which is located within a wall-or a floor-ceiling space where:

a.

Both sides of the space are exposed to conditioned air.

b.

The space is not ventilated.

c.

The space is not used as a return plenum.

d.

The space is not exposed to unconditioned air.

Ceilings which form plenums need not be insulated.

INSULATION TYPES:

A.

1-inch, 0.60 lb./cu.ft. mineral fiber blankets and felt, rock, slab or glass.

½-inch, 1.5 to 3 lb./cu.ft. blanket duct liner, rock, slag or glass.

½ inch, 3 to 10 lb./cu.ft. board mineral fiber, rock, slag or glass or equivalent to provide an installed conductance = 0.48.

B.

2-inch, 0.60 lb./cu.ft. mineral fiber blanket

1-inch, 1.5 to 3 lb./cu.ft. board, mineral blanket (duct liner)

1-inch, 3 to 10 lb./cu.ft. mineral fiber board or equivalent to provide an installed conductance = 0.24

C.

3-inch, 0.60 lb./cu.ft. mineral fiber blanket

1 ½-inch, 1.5 to 3 lb./cu.ft. mineral blanket (duct liner)

1 ½-inch, 3 to 10 lb./cu.ft. mineral fiberboard or equivalent to provide an installed conductance = 0.16

V.

Vapor Barrier: Material with a perm rating not exceeding 0.5 perm. All joints to be sealed.

W.

Approved weatherproof barrier."

(Ord. No. 39-287 (part))