Solar Attic Fan

US Sunlight Model 1010 TRS An attractive $250 at Costco.

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Solar Attic Fan

The roof cut is a clean 14” hole through shingles and sheathing.

Seal with a heavy bead of elastomeric polyurethane sealant*, oozed into each layer of shingles, buttered down with trowel.

Lift tabs and pull staples in this zone. Lift as a group, and drop onto sealing collar.

*BASF Sonolastic TX 1. From LightBenders. I have not found a local supplier in color black.

28 gage galvanized steel, 24” square. 14” male collar 2.5” tall. A 1.5” collar would have been better, avoiding interference of fan braces.

Roof Cut and Sealing Collar Plan Metric Three-Tab Composition Roofing Scale 1:16

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Solar Attic Fan

IMG_3782 9/12/2011, 1:15 PM

Shingles are cut in sweeps of deck screws, set in a 16” length of 2x2 lumber. A 3” #10 screw forms the pivot. Cutting is with symmetrical 2” #9 deck screws.

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Solar Attic Fan

IMG_3783 9/12/2011, 1:26 PM

This is the only revealing of the 15/32” thickness plywood roof sheathing. Felt paper outboard of the circle will not be disturbed more than by the removal of shingle staples.

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Solar Attic Fan

IMG_3784 9/12/2011, 3:24 PM

The hole was cut with a corded Sawzall. I wanted to tilt the saw to not grab shingle edges, working from above. See sawdust on right. With insecure footing, it was easier to complete the cut from the attic. With a pilot hole and the shingle cutter/ scribe, the circle could be marked both above and below.

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Solar Attic Fan

IMG_3785 9/12/2011, 3:38 PM

The freed array of shingles easily lifted over the inserting adapter plate and collar. The plate is retained by reset roofing nails. The 2 1/2” rim height will interfere wth braces in the fan. Zones in red will be folded-in.

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Solar Attic Fan

IMG_3788 9/12/2011, 3:56 PM

Looking at annulus LHS. The sealant is well buttered into the annulus and between involved shingle layers. This is a high-quality sealant, that will remain resilient. It will not hurt that the bead will be protected from weather and sunlight, by the fan body.

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Solar Attic Fan

IMG_3790 9/12/2011, 4:39 PM

Four 2” deck screws tightly bind top and bottom of the fan base. Top screws are about 1” hidden under a shingle course, I might have tarred the revealed screws. The solar collector may be tilted toward vertical, but this angle matches that of the roof and of the photovoltaic arrays below.

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Solar Attic Fan

IMG_3792 9/12/2011, 4:40 PM

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Solar Attic Fan

IMG_3793 9/12/2011, 4:40 PM

The fan grabs some more sun. In Summer, there will be no shadowing by the gas B-vent, which is perhaps now idle, and might be converted to an atticilluminating skylight or other solar collector.

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Solar Attic Fan

19”

2x4 on flat

2x4 upright

22”

IMG_3794 9/12/2011, 5:10 PM

Four pieces of 2x4@22 5/8” were preset to accept 2” deck screws (in red), retaining the fan body. Screws on left align with a roof joist, needlessly. The 2x4 blocks catch right-hand screws, and support the plywood sheathing, which is weakened by the 14” cutout.

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Solar Attic Fan

IMG_3795 9/12/2011, 5:10 PM

The fan could not have been much nearer the roof peak. Note a separation line between roof sheathing that would have been challenged by cutout and by the fan weight. The 2x4 blocks will be mandatory, even where there is not an unlucky sheathing array. One must not trust fan attachment to sheathing only.

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Solar Attic Fan

IMG_3805 9/16/2011, 10:49 AM

The fan creates small vacuum in the attic, drawing from everywhere, including the here-open attic ladder. A fan might draw from stored solar power to draw down house temperature for an hour or so, on a cool summer evening. A partially-dropped ladder would pull some from the interior space, blowing against any light-seeking attic critters. Such night-time cooling would work by stack effect, even without fan power. Manually turning on a solar fan for a time might be daunting.

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Solar Attic Fan

IMG_3805 9/16/2011, 10:50 AM

Solar fan in context with ladder, lights and decking. An attic should not be a dark and dangerous place. It should not be a garbage pit for roof innovation and maintenance. Access allows the applied sheathing reinforcement for the fan, with 2x material for engagement of fan-mounting screws. It was easy to pick and vacuum cut debris from this storage deck.

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Solar Attic Fan

W

S

IMG_3811 9/16/2011, 12:44 PM

Add another solar fan, facing West. Convert B-Vent to Attic-illumination dome.

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