Persistent soil smell in room furthest from Radon system—Will a bigger fan (RP265) fix a "Dead Zone"?
I recently professionally encapsulated my crawlspace and later installed a Radon system (RadonAway RP145) for radon and terrible crawlspace soil gas odor post-encapsulation. It’s helped significantly, but I still have an odor in the room furthest from the fan. My radon levels are low (usually under 0.5), but the smell correlates with the minor spikes in that room (0.6 to 1+).
The house is a two story colonial with hard clay soil. The fan pulls from the garage slab and the crawlspace. I think the garage slab is "stealing" all the suction, leaving no vacuum for the far end of the house where the smell is. My manometer shows 0.5”.
I want to DIY swap the RP145 for a more powerful RP265 to avoid having contractors back inside the house (immunosuppressed family member).
What should I be worried about besides backdrafting? I know how to test the gas water heater in the garage for backdrafting with a smoke pen, but are there other risks to "over-fanning" a house? The garage water heater shares a chimney with a gas furnace there. The other gas furnace is on the attic. No other gas appliances.
Does a fan upgrade actually work for localized odors, or is a second suction point from my original fan to the further location the only real cure?