We are selling my folks home and had the opportunity to have a radon mitigation system installed. The buyer required it;-(
It consists of 4 inch PVC installed in a hole through the floor and sealed. There is a small pit dug out to make an air (radon?) space for the fan to pull a vacuum from under the floor.
Part of the install features a manometer to show that the pressure under the slab is less than above the slab. The idea is radon will not come up through the slab and any movement will be air going down.
Out side view. Vents above windows.
Fan nameplate. The fan curve shows 18 cfm at 3.5" WC.
You can see a few drops of condensation at the outlet. A side benefit is supposed to be less humidity in the basement.