Month: July 2010

Sound Reduction part 4 – Ducted Models

The final step on our journey of sound reduction brings us to ducted AirScape models. As you already know the ducted design of the 2.5 WHF, 2.5e WHF, 4.4e WHF, 4.5 WHF, and the Kohilo 2.8 allow for maximum airflow with a minimum of noise. Improper installation of these models can increase their sound levels. We touched on this subject earlier in the blog “4.5 Installation – Maximize Airflow, Minimize Noise.” There are a few things you need to consider when installing a ducted model.

90 DEGREE BEND –  The 90 degree bend should be as smooth as possible to maintain the 20″ diameter of the ductwork. Kinking the ductwork will increase the sound level and reduce airflow because the air does not have a smooth path to the fan.

EXTENSION –  It is important to extend the ductwork as far as possible away from the damper box. This needs to be done without distorting the 90 degree bend in the ductwork. Extending the ductwork fully moves the sound source (the fan) to the farthest point from the living space.

D-RINGS –  The 2.5, 2.5e, and 4.4e fans have D-rings which are used to hang the fan from the attic rafters. Only 4 of the 8 D-rings are used in the installation. The unused D-rings should be taped down to avoid excess rattling.

PART 1 / PART 2 / PART 3 / PART 4

Sound Reduction part 3 – Raised Frame w/ Ductboard

The next logical step for sound reduction is to combine the raised frame concept and add the duct board mentioned in part 1. In the following steps we’ll show you how to do this type of install.

STEP 1:  First we created two frames with inside dimensions of 14.5″x22.5″ using 2×4’s.

STEP 2:  Next we made a box using the two frames from step 1 and 3/8″ plywood. For this example we made our raised frame 17″ tall using (2) 25.5″ x 17″ and (2) 18.25″x17″ pieces of plywood. The vertical clearance of your attic will determine how tall of a box you can create. The picture shown is with one side removed.

STEP 3:  Position the box over the framed opening and secure. Caulk all of the seams and gaps of the newly constructed raised frame. Attach the provided gasket to the upper frame of the box. Line the box between the 2×4 frames with duct board. In this example we used (2) 24″x10.75″ and (2) 16″x10.75″ sections of duct board. We decided to go with a friction fit, but adhesive or screws with flat washers would work as well.

STEP 4:  Position the unit on top of the raised frame (1.7 shown). Secure using the provided screws. From the living space caulk all the gaps between the unit and the framing. You can now follow the remaining steps in the installation and operation manual to finish your install.

PART 1 / PART 2 / PART 3

New Rebates!

We are excited to find that a few utility companies outside of California are now offering rebates for whole house fans. It’s nice to see some forward thinking by these companies. After all, energy savings can come from more than just replacing appliances or installing new windows.

Fort Collins Utility in Colorado is now offering a $250 rebate for the installation of a whole house fan

Pennsylvania is the first East Coast state with utilities offering rebates on whole house fans. PECO and Duquesne Light offer $90 and $130 rebates respectively

If you are a builder in Utah you can receive a $200 rebate on a WHF from Rocky Mountain Power when building a new energy efficient home

The table below lists all of the rebates that we are aware of for whole house fans and solar attic fans (your solar attic fan already qualifies for a 30% federal tax credit). Please refer to the utility rebate website for specific details on qualifications, $$$, and application forms.

STATE UTILITY WHF* SAF*
CA LOS ANGELES DEPARTMENT OF WATER & POWER $200
CA LODI ELECTRIC UTILITY $100 $40
CA RIVERSIDE PUBLIC UTILITIES $200
CA SILICON VALLEY POWER $200 $100
CA GLENDALE WATER & POWER $100-$125
CA BURBANK WATER & POWER $50-$100 $200
CA ANAHEIM PUBLIC UTILITIES $100 $30
CA PASADENA WATER & POWER $100
CA SOUTHERN CALIFORNIA EDISON $50
CA SAN DIEGO GAS & ELECTRIC $50
CA REDDING ELECTRIC UTILITY $150
CA TURLOCK IRRIGATION DISTRICT WATER & POWER $75
CA SACRAMENTO MUNICIPAL UTILITY DISTRICT $100
CA MODESTO IRRIGATION DISTRICT WATER & POWER $100 $50-$100
CO BOULDER COUNTY $500
CO FORT COLLINS UTILITIES $250
PA DUQUESNE LIGHT $130
PA PECO $90
TX GUADALUPE VALLEY ELECTRIC COOPERATIVE $50
UT ROCKY MOUNTAIN POWER $200
*Please refer to utility for rebate details

Trains and coal strange bedfellows

We love railroads. Who can’t love their efficiency. BUT… They like coal. They really like coal. According to this report 44% of railroad car traffic is coal. And coal is dirty. It’s dirty in terms of carbon emissions. It’s dirty (but can be cleaned) in terms of particulate emissions. It’s not all that wonderful in terms of mercury dispersal either.

So, which way do you think railroads will lobby (they are corporate “citizens” after all).  Will they throw their weight towards laws which reward efficiency => win for rail transportation. Or will they throw their weight behind more coal burning => still good for railroads.?

Sound Reduction part 2 – Raised Frame

You may consider a raised frame for your 1.0 or 1.7 WHF for additional sound reduction. The raised frame increases the distance between the fan and living space. Like our ducted models, making the fan slightly more remote from the living space will decrease the overall sound level. The height of the frame will depend on the total vertical clearance of your attic. The construction is very simple and will add a few additional steps to your installation.

STEP 1: We made a raised frame using some scrap 2×4’s. The inside dimension is 14.5”x22.5” matching the framed opening. Secure the raised frame to the attic floor.

STEP 2:  Caulk all of the frame gaps and joints. Place the provided foam rubber gasket on top of the raised frame.

STEP 3: Secure the unit to the framing (1.7 WHF shown). From the living space caulk all gaps between the unit and the framing.

STEP 4: It’s not a bad idea to add some insulation around the raised frame. You can now follow the remaining steps in the installation and operation manual to finish your install.

PART 1 / PART 2


Sound Reduction part 1 – Duct Board

Your AirScape is already the quietest whole house fan on the market, but there are a few install techniques to make it even quieter. We’ve decided to dedicate a few blog entries to some techniques that will help with sound reduction.

We’ll start with a simple installation step that works with all AirScape models. You can easily line the inside of the framed opening (between the unit and grille) with duct board. Duct board is a resin bonded fiberglass board that has acoustic and insulative properties. The fibrous mat surface of the duct board helps absorb sound and allows for the smooth passage of air. The fiberglass body of this material usually has an insulation value of R-4. The duct board can easily be installed in new or existing installations using either adhesive or screws and flat washers. In fact, we love this material so much we lined one wall of our new office with it (our lead engineer’s rants on energy efficiency, life, and politics are a little more muffled now).

Duct board resources:

http://www.specjm.com/products/ductboard/enviroaire.asp

http://www.owenscorningcommercial.com/data/products/product.aspx?id=271

http://www.certainteed.com/products/insulation/hvac-mechanical/317382

PART 1 / PART 2