Here are the top sources – all telling the truth about their air flow as the California Energy Commission has requested. All the specs below are proven by having been tested to the Home Ventilation Institute’s test spec, HVI-916. The fans made by each company are very similar designs – 24 inch blades on 3/4 HP motors. These have shown to be the best in the industry. The reason Tamarack is the leader is because of their higher performance blade. Thorwaldson is now selling the Tamarack fan as well as the VentCool fan and offering an infinitely variable speed option. Kurt Shafer, founder and inventor, now has the only rooftop mounted whole house fan and he makes it using any of the fans below. The huge difference is that without the flexible duct in an attic to restrict air flow, the aif flow is expected to be over 7000 CFM with the Tamarack design and over 6000 with the VentCool or Airscape design.
QuietCool is the one company that refuses to comply with the CA Energy Commission. True, they did agree in writing in 2017 to publish their HVI-916 performance after paying $210,000 in fines to the state, but they still publish exaggerated and false performance figures that are propagated all over the internet.
Their model number ES-7000 has been tested to HVI-916 and pulls 5170 CFM. But the QuietCool specification sheet says it pulls 6,878 CFM on high speed. Under that QC adds “HVI-916 5170”. The result is that there are several large online retailers that have their main page saying “QuietCool ES-7000 whole house fan 6,878 CFM”. Below are some of those retailers.
WholeHouseFan.com – they have the ES-6000 showing 5,665 CFM on the first page.
REWCI.com – has ES-7000 at 6878 on pg 1 and HVI on pg 2.
EComfort.com has ES=7000 at 6878 on 1st pg and HVI on pg 2.
IndustrialFansDirect.com has ES-7000 on 1 st and 2nd no HVIAmazon.com
WholeHouseFanDeals.com – this site goes to wholehousefan.com see above
Walmart.com has ES-7000 says 7000 CFM no specs
HomeDepot.com – has ES-7000 at 6878 no HVI 3rd pg to get specs
Lowes.com – has ES4700 at full cfm and HVI lower on pg. No cfm in top selector.
Here is one retailer without QC – Sears.com
Page revised 6-10-19