Form over function sucks, but duct tape helps

[Dusted]

I just installed a 900 cfm range hood in my kitchen. Twin centrifugal blowers into collector with 6 inch exhaust vent. Turn it on and find that in addition to sucking huge amounts of air, it also blows out in the opposite direction from half of the intake on both blowers. Manufacturer says I installed it wrong! Anyway it was obviously incorrectly engineered, maybe due to appearance. Instead of the funky, space age, twin 6 inch intake screens they should have made throttle plates to properly contain the intake air. Duct tape to the rescue. Any place the intake blew back at me I taped it up. Ended up covering a bit more than one third of each intake screen. Intake surface area is still greater than exhaust outlet by quite a bit so I shouldn’t be starving the blowers. Rant over

 

[Jackalope]

Sounds like the 6" duct was not enough to take all the air volume too. While there may have been issues in how it held the air in it all should have went out if there was room. This would create pressure and blow back.