Hoping this is in the right category, please move if needed. I have a fairly new house (purchased Jan 2019) and have run a radon test twice. We are over the level and I'm looking at putting in a Radon Mitigation system. I want to do it DIY, but Boy, do I have questions. Let's start with the fact that the basement already has a Radon Mitigation connection installed. (See Pic) BUT, the problems come in when I do my research. ALL Radon Mitigation Fans are made for either 3" or 4" PVC connections and THIS thing is 3½ inches. How exactly does that work? I can find couplers made for connecting 3 to 4 and for connecting 4 to 3, but there are not any for 3.5". am I missing something? [img]https://cimg8.ibsrv.net/gimg/www.doityourselft.com-vbulletin/1500x2000/img_0810_1__a11000ace7c2935932df54f36a2dbce709453b79.jpg[/img]

I've seen this topic come up in a few searches but none seem to fit this situation. I understand that each floor should have at least one return and that this includes the basement. I'm finishing half of my 900 sq ft basement. Half fully finished and half unfinished utility/work room. There is a wall basically down the middle that I framed and (mostly) insulated. There are no forced air heating vents in the utility area. In the finished zone I have in-floor heating. There is a the original ceiling heat vent serviced by a 4 inch duct. Additionally, I added a floor level heat vent serviced 5 inch duct. In the unheated utility room where the furnace is located, is original, ceiling mounted air return. Questions: - I assume I should at least bring the return vent in the unheated utility room down to near floor level? - Does the heated, finished room require its own return vent connected to the return duct? (not sure if that's possible) or - If not should I install a grille at floor level... allowing return air to flow from the heated finished room to the unheated utility room? (along with lowering the return in the unheated room) - Are there any potential problems that could arise from leaving a basement room unheated? Primarily on the dividing wall? Thanks as always.... I'm putting a lot of time and effort into this basement and I don't want to fall down because I overlooked some detail.