I have to totally agree with rnen on staying away from big box stores when it comes to installation. The big box stores have significant track records for bad workmanship. The big box stores don’t actually do the installation, they shop it out to local contractors and then tack 10% (or more) onto what the contractor is going to charge. Cheapest contractor wins the work.
My personal experience with having Home Depot install a Whole House Fan was a nightmare because of their sub-contractor. Waited three months for installation. Dozens of phone calls and trips to the store to complain. Finally canceled the installation and found a contractor myself who had the thing up within days.