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September 26, 2018 The reason that QuietCool still shows 2 performance levels is now clear – in 2017 the California Energy Commission forced QuietCool to agree to posting the true HVI-916 test results for each of their models. All the suppliers including QuietCool changed their web sites to comply with that. But QuietCool still insists on showing a higher number along with the HVI-916 number. They say the higher number is    “*Listed airflow specs are tested via a device that is calibrated to NIST standards.” which is meaningless because NIST does not have a standard for testing like the HVI-916 has.

July 30 2018 You might have noticed the new data being presented by suppliers of whole house fans that show two performance levels of air flow in CFM. One level is higher, the other, called “HVI-916” is lower. The reason is not yet clear but will be explained here soon.

July 23 2018 This blog is about performance. Every whole house fan company says they have the best performance – or the best price – or the best quality. And there is a huge new brouhaha over CFM ratings. We think that performance should be simply the amount of air flow and the amount of electric power needed to move the air. We would appreciate your input on that to Performance@thorwaldsonwholehousefans.com

July 16 2018 This blog is about true air flow measurement. In the past most sources used air flow measurements that were largely undefined. HVI-916 was an attempt to define a test setup and procedure for an industry standard. It is our opinion that the best air flow measurement is one where the fan is in an attic and pulls air from a tightly closed house with just one window open- a 2 foot high window open 6 inches. The opening is therefore exactly one square foot. It happens that the air flow in feet per second is exactly the same as the flow in cubic feet per second. This test is ideal for both initial product testing and for final acceptance tests in a home. So, as an example, you can see a window with the drapes flying here- http://thorwaldsonwholehousefans.com/testimonials/case-studies/gearard-in-california-2012/