Radon fan replacement and system checks: is your system still working?

How to tell if your radon fan is working

Most systems have a U-tube manometer on the pipe: a small clear tube with colored liquid. Some also have an alarm. The fan is meant to run all the time; the EPA says it should never be turned off.

Here’s how I describe it: when the system is producing the suction it was designed for, the two columns of liquid sit at different levels. When I start up a system, I mark the normal reading and show the homeowner what it looks like.

Gauge liquid

Radon manometer readings explained

There’s no single reading, in inches of water column, that’s right for every fan and every house. That’s why the installer should mark yours.

If the columns become level, the system may have lost suction: maybe the fan quit, or the gauge tube came loose. It should be checked. The reading can vary a little, but if it moves a lot from its usual mark, have it looked at.

And the manometer doesn’t measure radon. It measures pressure, not concentration. Only a test tells you the radon level in the house.

Radon fan troubleshooting by symptom

Most failures I see are motors that eventually give out, vibration from rigid mounts, worn connections and water in the pipe. Warning signs are a new noise or a louder hum, vibration, an alarm if there is one, or a manometer that’s off from its normal reading. Sometimes there’s no noise at all, and the fan just stops. That’s why I tell owners to check the manometer from time to time.

Noise and vibration

First, I listen for where the noise is coming from. Is it the motor? Is the PVC humming? Is the whole wall vibrating? Not every hum means the fan needs replacing.

I check the mounts, clamps and flexible couplings, and whether the pipe is resting on framing that carries the noise. I also look for water in the pipe. If there’s a new noise coming from the motor, I inspect the fan before it fails.

Water, condensation and ice

The gas pulled from the ground carries moisture, and in winter that moisture condenses. That’s why the pipe should slope so the water drains back where it belongs instead of pooling and restricting the airflow. In colder climates, I also look for ice at the discharge.

I don’t advise owners to cut or turn the pipe themselves. The discharge has to stay a certain distance from openings, in the right position.

Radon fan replacement: when and what it costs

For planning, I’d figure on replacing a fan every 5 to 10 years, but I wouldn’t put a universal life span on one. Some last much longer and some don’t, depending on moisture, ice or a system that strains the fan. I judge a fan by how it runs and the pressure reading, then confirm with a test. Radon has no smell and gives no warning, so I don’t wait for one.

Angi puts radon fan replacement cost at about $150 to $350, typically every 5 to 10 years (April 2026). The new fan has to match what the system needs, not just fit the pipe. For the cost of a whole system, see radon mitigation cost.

Can you replace a radon fan yourself?

I wouldn’t advise it. It looks easy enough: two pipe couplings and an electrical connection. But you need the right fan, mounted in the right place, with no leaks and a protected circuit.

What you can do is watch the manometer and report any change. I’d want a professional to replace the fan and check the pressures, then a follow-up test to confirm your radon level. Depending on your state, the person doing that work may have to be licensed or certified.

Radon mitigation system maintenance

• Glance at the manometer every month or so and compare it with the installer’s mark.
• Listen for new noise or vibration.
• Look at the outside discharge after storms and in freezing weather.
• Retest at least every two years (EPA), and after repairs, renovations or foundation work.
• Keep the system label, the install paperwork and your test reports together.

New to radon? Start with radon in your basement. Still deciding whether your system is right for the house? See how radon mitigation systems work and how to test for radon.