Radon fan location: outside via drain tile?
Per the oft cited recommendation, we installed a passive radon pipe in our home during construction. It’s piped off the foundation Form-A-Drain and incorporates a top of the house area with electrical circuit and enclosure for the radon fan. We are now at the point where it probably makes sense to install that fan. In fact the fan is here ready to be plumbed in. (I have good reason to believe the passive radon pipe vent works, at least to some degree; certain times of the year you can see frozen water vapor near its output.)
Our radon results hover around 4 to 6 pCi/L. This a composite of a series of readings the last three years that include 2 short term charcoal tests from Air Chek, 2 four month long canister tests from AccuStar, and a Corentium real time radon meter running since last November 1st. These measurements all taken on the ground floor.
Important note: The aforementioned tests were largely taken during the winter where it is generally assumed radon is at its worst due to stack effect, wet and frozen soil outside, and general sealing up of the house. A spot check with the Corentium late summer / early fall indicates levels below the 4 pCi/L recommended action level. One of the late spring charcoal tests corroborates that trend coming at 2 pCi/L. (I have a late spring first floor test charcoal test that, as expected for an upper level, was much lower, .7 pCi/L.)
So now to the question, do I plunge forward and put the fan in the existing radon piping, with a radon alarm nearby in case it were to fail? Or, do I install it outside?
As it turns out, due to a change in how we wanted the land graded near our home, our Form-A-Drains daylight into “wells” near the home. My intention was to fill the wells with 2B stone, and then bury them as we do our final landscaping near the house. Here is the thing, one of those wells happens to have a conduit direct to the electric panel. Not only that, this well has connectivity to a separate perf drain run under the center of the house. Ostensibly that secondary perf drain, buried at ground level under a few triaxles of clean 2B stone, could perform significantly better than the main Form-A-Drain as a radon exhaust pathway.
I found an example of a somewhat similar outdoor radon venting scheme. Anyone have experience with same? http://www.radonfree.com/downloads/drain2daylight.pdf
PS 1: Yes, I am aware of the “hire a radon expert” clause.
PS 2: I spend 99 percent of my indoor time on the 1st floor. One of the cats does sleep downstairs a few hours a day though.
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