So far I have installed one for the main portion ...

So far I have installed one for the main portion of our home. Another unit will go up before summer. It wasnt hard to install. I think the hardest part of the install was cutting into our newly textured ceiling. I mentioned going into the attic before summer hits because it was in the range of 120 degrees in the attic when I did the first install. Trust me, take care of it now before the heat gets here.

I also ordered and installed the QC remote controller which saved me a ton of hardwiring. The main box gets installed on the main fan unit in the attic and was not hard to accomplish.This works from your phone and allows you to control the fan speeds and how long you want the fan to run (the timer).
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As far as savings and other benefits. We rarely have to use the air conditioner. Thats a humongous savings right there! W do as is suggested and leave the house sealed up during the hot part of the day and then in the evening, when it's cooler, we crack certain windows which gives us good airflow and then we turn on the QC fan. It works great and cools off within a very short period of time.

We just had a new roof put on in 2017 and hope this will add to its longevity.

I would suggest this QC whole house fan to anyone who wants to lower their home cooling bill. This is one of the better home improvement items you can do to a home.