A radon fan, sometimes called a radon blower, is the motor of a radon mitigation system. It sits in the vent pipe and runs all the time, pulling soil gas from under your foundation and pushing it out above the roof. That suction keeps the air pressure under the slab lower than the pressure in your home, so radon flows into the pipe instead of into the house (EPA, Consumer’s Guide to Radon Reduction). Systems with a fan reduce radon more effectively than passive systems without one.
Where a radon fan goes
The fan has to be outside the living space: in an attic, in a garage with no living space above it, or on the outside of the house. It can never be in a basement, a crawlspace or anywhere in or below a lived-in area (EPA, Consumer’s Guide; MDH). Keeping it in unconditioned space prevents radon from leaking back into the home (MDH).
EPA’s installation standards add more rules for the fan itself (EPA, Radon Mitigation Standards):
- It is designed or sealed to keep soil gas from leaking out of its housing.
- An outdoor fan is rated for outdoor use or sits in a watertight housing.
- It is mounted in a vertical run of pipe where possible, to avoid condensation building up inside it.
- It is mounted so it passes as little vibration as possible into the house framing.
- It is connected with removable couplings, so it can be serviced or replaced.
- A fan mounted outside is hard-wired, and the circuit has a disconnect switch or breaker for servicing.
Power use and running cost
Radon fans typically draw less than 90 watts, similar to leaving a 60- to 90-watt light bulb on all the time (National Radon Program Services, Kansas State University). Running continuously, that is about 530 to 790 kWh a year. At the US average residential electricity price of 18.16¢ per kWh in August 2026 (EIA), that works out to roughly $95 to $145 a year. Your cost depends on your fan’s wattage and your local rate.
There is a second, smaller cost: the system draws some heated or cooled air out of the house along with the soil gas. Good sealing of the foundation keeps that down (Kansas State University; EPA, Consumer’s Guide).
Choosing the fan
The installer sizes the fan for the house, sometimes after diagnostic tests that show how easily air moves under the slab (MDH). How many suction points a home needs depends on how easily air moves through the gravel or soil under the slab and on how strong the radon source is (EPA, Consumer’s Guide). That decision is part of the system design, which is why EPA recommends a qualified contractor.
How to tell it’s working
Every active system should have a warning device where you can see or hear it (EPA, Consumer’s Guide). Most often it’s a U-tube manometer, a small liquid-filled gauge on the pipe (MDH). When the fan is pulling suction, the liquid sits higher on one side than the other. If the two sides are level, the fan isn’t working. Some systems also have an alarm that sounds if the fan stops. Note where the liquid sits when the system is new, and look at it regularly.
Never turn it off
The fan must run continuously for the system to work. Turning it off lets radon build back up (EPA, Consumer’s Guide).
How long radon fans last
EPA says fans may last five years or more, and manufacturer warranties tend not to exceed five years. Kansas State University’s radon program gives typical lifespans of 10 to 15 years (EPA, Consumer’s Guide; Kansas State University). When a fan fails, it can be replaced without redoing the system. See radon fan noise, lifespan and replacement and what a replacement costs.