Existing system help

Is my radon system working?

Written and reviewed by Bill Dahlstrom, Illinois radon mitigation license RNM2018212 · Updated

Maybe you bought a home that came with a radon system, or yours has run for years and you want to know it still works. This page shows what each part does and when to call.

Quick checklist

What should I check first?

Look at the pipe

Is it still connected, in one piece, and ending outside where it used to?

Listen to the fan

Is it a quiet hum, a loud grind, or nothing at all?

Check the gauge

Is the liquid higher on one side than the other? That usually means the fan is pulling.

More on each part is below. If something looks wrong, the list of signs further down says when to call.

First check

How do I read the gauge?

The clear U-shaped gauge on the pipe is called a U-tube manometer. It shows whether the fan is still pulling on the system.

If the liquid is higher on one side, the fan is usually pulling. If both sides are even, the system may not be pulling and should be checked. The gauge tells you more than the fan sound does.

The gauge does not measure radon. To know your radon level, you have to test the home. With the fan running, you can use a free or low-cost Illinois county kit.

Radon system manometer and state license tag on PVC pipe
System parts

What does each part do?

Exterior radon fan and disconnect mounted on the side of a home

The radon fan

The fan runs all the time. Most make a soft, steady sound of air moving through the pipe. A new rattle, grinding, or shaking is worth a look. If the fan goes quiet, check the gauge.

Read about fan replacement and repair →
White radon mitigation pipe routed through a basement

The pipe

The pipe carries the radon from under the floor to the outside. If a section is loose, cracked, or pulled apart, have Bill look at it.

Sealed sump lid with access port for a radon mitigation system

The sump lid

A sealed sump lid helps the system pull from the right place. The lid still has to let you get to the pump when it needs work.

Sealed crawlspace plastic used with a radon mitigation system

Crawlspace plastic

In a crawl space, the system pulls from under sealed plastic. Torn plastic or open seams can keep it from pulling well.

Outside

The pipe outside

The pipe outside should send the radon out above the roofline. If it looks loose, damaged, or different than it used to, have it checked.

To see how we plan a new system, read what to expect during install. If you want the fan, the gauge, and the pipes looked over, ask about a radon system inspection and checkup.

Which photos help Bill?

  • The fan and its label, if you can reach them safely.
  • The gauge on the pipe.
  • The sump lid or the spot where the pipe goes into the floor.
  • The outside pipe, from the fan up to the roof.
  • Any torn plastic or open seams in the crawl space.
When to call

When should I call Bill?

The gauge is level on both sides, or it reads very differently than it used to.

The fan is loud, grinding, rattling, shaking, or not running.

A pipe looks pulled apart, cracked, loose, or unfinished.

The sump lid is loose or no longer sealed.

The crawl space plastic is torn or the seams have opened.

A new radon test came back at 4.0 or higher.

“Great team! Professional installers & responded recently to an issue with a loud fan. They were quick to answer my call and quick to perform repairs.”
Lauren G · Birdeye · December 2025
FAQ

Questions about radon systems

Fan sounds, the gauge, and upkeep.

Does the radon fan run all the time?

Yes. A healthy mitigation fan runs continuously, and it should not be switched off in winter or while you are away. Whenever it is off, soil gas has its normal path back into the house, and the system gives no protection until it is running again. In our experience, running it year-round adds roughly $60 to $125 a year to the electric bill, depending on the fan and your rate. A light steady hum can be normal. If it gets loud, rattles, or goes silent, call Bill; that is a service call, not a switch.

Is sealing the sump necessary for radon mitigation?

Often yes. An open sump is a common soil-gas path. We typically seal the sump with a lid that still allows pump service and access. Sealing alone is not a full mitigation system, but a proper lid is usually part of a good design when a sump is present.

My radon fan is noisy. What does that mean?

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. We can usually come out within a day or two, including systems another company installed. There is no trip charge. A fan replacement is $575, including the fan, the visit, the labor, and a new five-year fan warranty, and Bill confirms that before the visit. 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. Call Bill’s cell at (815) 370-9682, and send a clear photo of the fan and manometer if you can.

My radon fan is silent. Is it broken?

A properly working radon fan is not perfectly silent. Most produce a soft, steady sound of air moving through the pipe. If the system becomes completely silent, check the U-tube manometer. A working U-tube manometer normally shows the two liquid columns at different heights. If the columns are level with each other, the system is not showing suction. The manometer shows suction, not the radon level in the home. Call Bill’s cell or send him a photo of the gauge. Service is usually within a day or two.

How do I read the U-tube manometer?

The manometer is the small clear U-shaped gauge on the pipe. It shows suction, not the radon level in the home. Uneven liquid levels usually indicate suction. If both sides 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 at (815) 370-9682 (his cell).

Can you service my radon fan brand?

Almost always. We work on RadonAway, Fantech, Festa, and other common radon fan brands, including systems another company installed. If you are not sure what you have, text Bill a photo of the fan label and the U-tube manometer.

Does a radon system need maintenance?

Very little. Glance at the U-tube manometer now and then to confirm the liquid is uneven, listen for the soft, steady sound of the fan, make sure the outside pipe and fan look secure, and leave sump lids and sealed openings alone. Retest every two years. Call Bill if the gauge goes flat, the fan gets loud or silent, or anything gets damaged.

Can a radon system freeze up in winter?

Yes. Any radon system can ice up if it gets cold enough. The fan pushes warm, damp soil air up the pipe, and in a hard freeze that moisture can frost over inside the top of the pipe and choke the airflow for a while. It clears on its own when temperatures come back up, and there is no reason to shut the fan off. Here is the part worth knowing. Radon risk comes from your average exposure over years, not from one cold snap. EPA bases the health risk on long-term exposure. Say the pipe iced up for two full weeks and the house went back to its untreated level the whole time. That is two weeks out of fifty-two. The other fifty weeks the system is pulling the level down as usual, so your yearly average moves only a little. If the fan sounds different or the gauge sits far from its usual mark after the thaw, send Bill a photo at (815) 370-9682.

Helpful official radon resources

Last reviewed by American Radon Systems: June 2026

Reviewed by Bill Dahlstrom, Illinois radon mitigation license RNM2018212.

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Call Bill's cell at (815) 370-9682, send a few photos to that number, or fill in your info.

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