Radon with two fans still high

[Rman]

I have a 3/4 basement with 8 foot ceilings. Home built in 2015
There is a 3 inch perforated pipe below the slab in the 6 inch gravel. The original radon readings were 22-24 pc/l. The allowable is 2-4 pc. I installed one radon fan outside then up to the roof. Reading dropped to 16 pc. Added a second radon fan in parallel outside. Reading is now 10-11 pc steady. I’m thinking that I need fresh air introduce to basement but not leaving a window open in north Nj. Is there a backwards vent type similar to a dryer vent that would allow air to enter but not the local critters? The boiler is a direct vent with fresh air supply on another pvc pipe to outside. As air is needed in the house 3 bath fans stove vent dryer will the fresh air intake help the Radon level or will it pull it upstairs to the living space? There is a sump pump but can’t be sealed too many pipes drain into sump. 2 central air. A water softener. A water filter system. Is it feasible to add a 3rd fan outside to pull more air outside. I installed this system while I was building my home and final inspection all passed. The local radon guys want to abandon my system and install new pipes etc. Thanks

 

[DIYorBust]

Who wants lung cancer? Nobody. That's why it's worth getting a pro for this if your system isn't working right. If you think there's a better way, why not get a second contractor to take a look?

 

[Sponsor]

 

[Olympia Pernille]

Radon is a radioactive gas that you cannot see, smell or taste and can get into your home undetected. Radon is dangerous. So Better look for a contractor to fix a radon problem just as you would choose someone to do other home repairs. It is wise to get more than one estimate if possible and to ask for references. Contact some of those references to ask if they are satisfied with the contractors' work. Be sure to get a written cost estimate that outlines all of the work to be carried out. This is for your good and the safety of your family.