Inline radon fans, sometimes called “radon pumps”, are extremely powerful air movers. Radon fans create vacuum pressure or suction–which is why they’re mistakenly referred to as pumps. They actively remove soil air (called mitigation or sometimes remediation) via a closed system. The technical term for this process is active soil depressurization. A–hopefully–trained and certified radon professional designs a system that forms a barrier between the insulated air inside the home and the soil. They then puncture this barrier layer and create a plenum which will be used to exhaust the radioactive air safely above the roofline of the home. Radon can be remediated or mitigated in other ways, however, these methods are often more expensive upfront or in the long term. Opening windows or adding fresh air make up can work for a short time; however, over the life of the home all new air that you bring into the house gets prohibitively expensive to heat or cool, so active soil depressurization is the preferred, economical and energy-efficient method.
Why are radon fans more expensive than other inline fans, you may ask? Great question! Soil air is very humid. Soils in North America typically have water vapors in them. Even desert regions with low moisture soils have water vapor in radon systems. This is because condensation will form inside the radon pipe due to temperature differences between cool soil air and hot exterior air (and vice versa depending on the time of year and region of the country). It’s been estimated that a radon fan can actively move up to 15 gallons of water vapor per day out from under the home. This is just the moisture that is removed: a side benefit to a well-designed radon system. Back to the question on cost: a radon fan must be able to withstand the onslaught of water that will drip through a system back to the soil, which means it needs a higher IP rating that most inline fans that only deal with conditioned air. This IP44+ rating means that radon fans can withstand more dust and moisture than your average fan.
Don’t skimp on radon fan selection. Get a trained professional to properly size your radon fan—your utility company will thank you for it.