--- title: "Is My Radon System Working? Checks and Upkeep" url: https://vermontradon.com/is-my-radon-system-working/ description: "How to check a radon mitigation system: read the gauge or alarm, keep the fan running, retest every two years, and what to do when a fan fails. EPA and Vermont guidance." last_reviewed: 2026-10-18 source: "U.S. EPA; Minnesota Department of Health; Vermont Department of Health; CRCPD. Each fact is footnoted to its source below." publisher: "Vermont Radon, an independent guide, not affiliated with the Vermont Department of Health or EPA. Not medical advice." --- # 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](https://vermontradon.com/find-a-contractor/) 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] [Order a retest kit](https://vdh.webapps.aidcvt.com/water_supplies/radon) [See Airthings monitors](https://discount.airthings.com?aw_affiliate=eyJjYW1wYWlnbl9pZCI6IjEiLCJ0cmFmZmljX3NvdXJjZSI6InZlcm1vbnRyYWRvbi5jb20iLCJhY2NvdW50X2lkIjoyNDI1N30) (Affiliate link) If you buy through the Airthings link, Vermont Radon may earn a commission at no extra cost to you. [How we make money](https://vermontradon.com/how-we-make-money/) The Health Department Lab kit is not an affiliate link. ## 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](https://vermontradon.com/buying-or-selling/). ## 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] ## Next steps - [Fixing radon: systems and costs](https://vermontradon.com/fixing-radon/) - [Find a certified contractor](https://vermontradon.com/find-a-contractor/) - [Monitors vs. test kits](https://vermontradon.com/radon-monitors-vs-test-kits/) - [Understanding your results](https://vermontradon.com/understanding-results/) ## Sources [^1]: **U.S. Environmental Protection Agency**. [Consumer’s Guide to Radon Reduction: How to Fix Your Home (EPA 402/K-10/005, 2025)](https://www.epa.gov/sites/default/files/2016-12/documents/2016_consumers_guide_to_radon_reduction.pdf). Checked 2026-10-17. [^2]: **Minnesota Department of Health**. [Radon Mitigation Systems](https://www.health.state.mn.us/communities/environment/air/radon/mitigationsystem.html). Checked 2026-10-18. [^3]: **Vermont Department of Health**. [Fixing Radon in Your Home (fact sheet, January 2024)](https://www.healthvermont.gov/sites/default/files/document/env-hh-radon-fixing-radon-in-your-home.pdf). Checked 2026-10-17. [^4]: **Vermont Department of Health**. [Radon in Your Home](https://www.healthvermont.gov/environment/healthy-homes/radon). Checked 2026-10-17. [^5]: **Vermont Department of Health Laboratory**. [Radon Test Kits (Health Department Lab webstore)](https://vdh.webapps.aidcvt.com/water_supplies/radon). 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)](https://www.epa.gov/sites/default/files/2015-05/documents/hmbuygud.pdf). 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)](https://aarst.org/TheRadonReporter/Radon-Reporter-December-2025/39). Checked 2026-10-17.