Adding more cold Air returns in basement

I live in Wisconsin, and have a Rheem furnace. Not sure on serial number or model, but it was put in last November. Central Air was installed this Spring. Here are some pics: http://imgur.com/a/QzFqF

I'm wondering if there would be an issue for me to cut into the duct work to add in 2 registers. My intent is that when I turn on the furnace fan, I want it to draw cold air from the basement up into the rest of the home.

I have a split level home with no doors between the upstairs and the downstairs, so the basement is sitting at 65F (or colder) most of the time, and the upstairs is sitting at 72 (which the thermostat is set on.)

I'm also considering picking up an ecobee3 and putting a sensor in the basement, so it will run the fan a bit more often to help normalize the temp a bit, without constantly running the Central Air unit. Seems sensible to me that drawing in more air from the basement and less from the upstairs is a good thing. Obviously, I would get a register cover that could be closed as needed.

Good idea? Bad idea? Where would I be making the best call if I was to cut into the duct? I assume on the picture labeled "front side," somewhere before the duct flares out?

Thanks!

Quick edit - I'm not worried about humidity or radon. Radon test was fine, and humidity is never above 50%. I've got a dehu that barely runs set at 50%.

submitted by /u/CRoswell
[link] [comments]