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Is my radon system working?

Like a furnace or chimney, a radon reduction system needs occasional maintenance. Look at its warning device regularly, keep the fan running, and retest at least every two years.⁠1

Check the gauge or alarm

A fan-powered (active) system has a warning device, usually a manometer, and the EPA says to look at it on a regular basis to make sure the system is working correctly.⁠1 A U-tube manometer is a small gauge on the vent pipe that visually indicates whether the fan is working. Some systems also have a monitor that sounds an alarm if the fan is not working properly.⁠2

Your contractor should explain how your system operates and how to maintain it, and give you written operating and maintenance instructions and copies of any warranties.⁠1 Keep them with your house papers, and ask the installer what the gauge should show when the system is working.

Keep the fan running

The fan should never be turned off. It must run continuously for the system to work correctly.⁠1

Fans may last for five years or more, and manufacturer warranties tend not to exceed five years. After that a fan may need to be repaired or replaced. The cost depends on labor and materials, so ask qualified mitigators for estimates before work begins.⁠1 In Vermont, the Health Department points to two directories of certified radon mitigation contractors, NRPP and NRSB.⁠3 Our contractor page links both.

After the work: retest, then keep watch

Test again after a system is installed to make sure levels are below 4.0 pCi/L, then test every two years to make sure it’s still working.⁠4 The Lab’s long-term kit is $25 and its short-term kit is $50.⁠5

Between tests, a digital monitor records radon continuously and can show unusual swings.⁠6 It doesn’t replace the retest: CRCPD says consumer monitors are not for mitigation decisions and to verify their results with an approved test.⁠7

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After you remodel

If you make major changes after a system is installed, such as turning an unfinished basement into living space, ask your radon contractor whether the changes could void any warranties. If you are adding a new foundation for an addition, ask what measures will keep radon low throughout the home. After you remodel, retest in the lowest lived-in area to make sure the work didn’t reduce how well the system works.⁠1

If your system is an HRV

A heat recovery ventilator used for radon control should run all the time. Its filter needs periodic cleaning and should be changed twice a year; the EPA puts replacement filters at $10 to $25. The outdoor fresh-air vent should be checked for leaves and debris, and a heating, ventilating and air-conditioning professional should check the ventilator every year to make sure the air flow stays properly balanced.⁠1

Selling a home with a system

If you sell a home that has a radon reduction system, the EPA says to tell potential buyers and give them information about how the system operates and is maintained.⁠1 More on buying or selling a home.

Common questions

How often should I retest after a radon system is installed?

Test again after the system is installed to make sure levels are below 4.0 pCi/L, then every two years to make sure it’s still working.⁠4

Can I turn off my radon fan?

No. The EPA says the fan should never be turned off; it must run continuously for the system to work correctly.⁠1

How long does a radon fan last?

The EPA says fans may last for five years or more, and manufacturer warranties tend not to exceed five years. After that a fan may need to be repaired or replaced.⁠1

Last reviewed How we source facts

Sources

7 official sources
  1. U.S. Environmental Protection Agency. Consumer’s Guide to Radon Reduction: How to Fix Your Home (EPA 402/K-10/005, 2025). Checked 2026-10-17. ↩
  2. Minnesota Department of Health. Radon Mitigation Systems. Checked 2026-10-18. ↩
  3. Vermont Department of Health. Fixing Radon in Your Home (fact sheet, January 2024). Checked 2026-10-17. ↩
  4. Vermont Department of Health. Radon in Your Home. Checked 2026-10-17. ↩
  5. Vermont Department of Health Laboratory. Radon Test Kits (Health Department Lab webstore). Checked 2026-10-17. ↩
  6. U.S. Environmental Protection Agency. Home Buyer’s and Seller’s Guide to Radon (EPA 402/K-24/001, March 2024). Checked 2026-10-17. ↩
  7. Conference of Radiation Control Program Directors (CRCPD). Consumer Digital Radon Monitors (CRCPD guidance, reprinted in The Radon Reporter, Q4 2025, p. 39). Checked 2026-10-17. ↩

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