Is My Radon System Working?
If you bought a home with a radon system, or your system has been running for years, it can be hard to know what is normal. Here are the parts homeowners usually ask about and the signs that are worth checking.
Four things to check first
Is the pipe connected, intact, and still terminated the way you remember?
Is the fan humming quietly, loud/grinding, or silent?
Is the fluid uneven (usually means suction) or flat on both sides?
Flat gauge, weird fan noise, loose pipe or lid, or a high retest. Call Bill.
Details on each part are below. Not sure what you are seeing? Call or text a photo to Bill's cell at (815) 370-9682.
Start with the manometer
The clear U-shaped gauge on many radon systems is called a U-tube manometer. It shows whether the fan is still applying suction to the system.
The manometer is not a radon test. The only way to know the radon level in the home is to test the home.
Uneven fluid usually means the fan is pulling. If both sides are level or flat, the system may not be pulling suction and should be checked. A working fan is usually quiet but often makes a soft hum or whisper of air up close; the manometer is the better confirmation. Not sure what you are looking at? Call or text a photo to Bill's cell at (815) 370-9682. That is his cell phone.
What homeowners usually ask about
The radon fan
The fan runs continuously. A properly working radon fan is not perfectly silent. Most produce a soft, steady sound of air moving through the pipe. A fan that becomes noticeably louder, rattles, grinds, hums, or sends vibration through the wall may be wearing out or may have another system issue that should be checked. If the system becomes completely silent, check the U-tube manometer. If the columns are level with each other, the system is not showing suction. If the reading changes substantially from its usual mark or the fan sounds different, send Bill a clear photo of the fan and manometer. We can typically come out the same day or the next day. Text Bill a clear photo of the fan and the U-tube manometer for a quick look. If the failed fan is one we installed and it is within the five-year warranty, the service visit, labor and replacement fan are included at no cost.
Fan replacement and repair - learn more
The pipe
The pipe moves soil gas out of the home. Loose, cracked, disconnected, or oddly routed pipe is worth having Bill look at.
The sump lid
A sealed sump lid helps the system pull from the right place. Access still matters, because the sump pump has to remain serviceable.
Crawlspace plastic
Crawlspace systems rely on sealed plastic and barrier details. Loose seams or torn plastic can affect how well the system pulls.
The exterior vent
The vent pipe should carry discharge safely outside and above the roofline. If the pipe looks loose, damaged, oddly terminated, or different than it used to, send a photo or call Bill.
If you are trying to understand how a full installation is planned, see what to expect during install. If you want the visible parts, fan, and gauge checked over, see Radon System Inspection & Checkup.
What photos help Bill
- The fan and the fan label, if it is reachable safely.
- The manometer on the pipe.
- The sump lid or suction point.
- The exterior pipe from the fan up to the roofline.
- Any crawlspace plastic, loose seams, or torn areas.
Signs worth checking
The manometer is flat or the reading changed noticeably.
The fan is loud, grinding, rattling, vibrating, or not running.
A pipe looks disconnected, cracked, loose, or unfinished.
The sump lid is loose or no longer sealed well.
Crawlspace plastic is torn or seams have opened up.
A radon retest came back elevated.
Related radon guides
Radon System Inspection & Checkup
Want Bill to look over the visible parts, fan, and gauge on an existing system?
Radon Fan Replacement & System Repair
What to check when a fan is loud, silent, vibrating, or not pulling correctly.
What to Expect During Install
How Bill plans a mitigation route, install day, cleanup, and walkthrough.
Radon Testing Guidance
What test results mean and when retesting is useful.
Before You Finish Your Basement, Test for Radon
Why radon planning is easier before finished materials are installed.
Helpful official radon resources
Last reviewed by American Radon Systems: June 2026
- CDC reducing radon levels in your home
Explains common radon reduction systems, including vent pipe and fan systems.
- U.S. EPA radon overview
Federal radon guidance, including why testing is the way to know a home's level.
- Illinois IEMA-OHS Radon Program
Illinois radon program information and licensing context.
Reviewed by Bill Dahlstrom, Illinois radon mitigation license RNM2018212.
Not sure what you are looking at?
Send a few photos or call Bill. We can usually point you in the right direction.