A radon mitigation system is one of the lowest-maintenance things in a house. It has one moving part, the fan, and no filters to change. But "low maintenance" isn't "no maintenance," especially in a crawl space home where plumbers, HVAC techs, and pest-control crews may be crawling over the membrane every year. This guide covers the checks Murfreesboro homeowners should do, the retest schedule, and the warning signs that mean it's time to call a professional.
The first retest
Every new system needs a post-mitigation test. It should start at least 24 hours after the fan is turned on, and industry practice is to complete it within the first 30 days. Use closed-house conditions, with windows and exterior doors shut for 12 hours before and during a short-term test, and the HVAC running normally. Many installers include this test; some buyers prefer an independent certified tester. The target is a result below the EPA action level of 4 pCi/L, and the EPA suggests considering further reduction between 2 and 4.
If the result is high, call the installer. Most certified mitigators guarantee a reading below 4 pCi/L in writing, and the fix is often more sealing, a better-sealed membrane, or an added suction point.
Your quick monthly check: the manometer
The manometer is the small U-tube gauge, usually filled with colored liquid, mounted on the vent pipe. When the fan is running, the liquid sits higher on one side. Installers often mark the starting level.
- Uneven levels, close to the mark: normal.
- Levels even, at zero: the fan has stopped, lost power, or the pipe is blocked.
- Reading much higher than the mark: possible blockage, such as water in the pipe.
- Reading much lower: possible leak, a torn membrane, or a weakening fan.
An easy habit is to glance at it whenever you change your HVAC filter.
Talk it through with a certified pro. Free referral for Murfreesboro and Rutherford County homes.
(629) 201-4576Listen to the fan
A steady low hum is normal. Rattling usually means a loose mount or pipe strap. A grinding or squealing sound can mean failing bearings. A fan that's silent with an even manometer needs attention. Check the breaker or outlet first, then call for service.
Fans run around the clock, so they eventually wear out. Many come with multi-year manufacturer warranties; keep the paperwork. Replacement is a routine job, and a certified mitigator can confirm the new fan is the right size.
Crawl space membrane care
This is the part that matters most in Rutherford County, where crawl spaces are so common.
- Ask contractors to be careful. Anyone working under the house should know there's a sealed radon membrane and avoid tearing it.
- Inspect after service visits. Look for tears, pulled seams, or loose edges at walls and piers.
- Patch promptly. Small tears can be repaired with compatible seam tape or sealant. Large damage should be handled by the installer.
- Watch for water. Pooling water on or under the membrane points to a drainage problem worth fixing. Middle Tennessee's heavy rains test crawl space drainage.
- Keep the access door closed. It's the boundary between the crawl space and the outdoors or garage.
Slab and basement homes
On slabs and basements, check that the seal where the pipe enters the floor is intact and that the sump lid, if there is one, stays sealed. New cracks after settling, or new openings cut for plumbing or electrical work, should be sealed.
Exterior checks
Look at the outdoor pipe and discharge a couple of times a year. Straps should be tight, joints intact, and the exhaust above the roof edge with nothing blocking it. Gutters and downspouts shouldn't dump water onto an exterior fan.
The long-term retest schedule
The EPA recommends retesting a mitigated home about every two years. Also retest after:
- Finishing a basement or adding a room
- Replacing the HVAC system or ductwork
- Major crawl space work, such as encapsulation or plumbing repairs
- Foundation repair or settling
- A fan replacement
Tennessee's free state kit works well for routine checks. For a sale, buyers usually want a professional test.
Talk it through with a certified pro. Free referral for Murfreesboro and Rutherford County homes.
(629) 201-4576Keep good records
Store the original test, the proposal and invoice, the post-mitigation result, the fan model and warranty, and each retest. A buyer's inspector will look for the manometer, the label, and recent results. See our home sale page for that process, and our cost guide for what affects the price of repairs and upgrades.
Frequently asked questions
How do I know my radon system is working?
Check the manometer, the U-shaped gauge on the pipe. Uneven liquid levels mean the fan is pulling suction. Then confirm with a radon test: the gauge shows airflow, not radon levels.
How often should I retest my home after mitigation?
The EPA recommends retesting about every two years, and after major renovations, foundation work, or HVAC changes.
How long do radon fans last?
Fans run nonstop, so they eventually wear out. Many carry multi-year manufacturer warranties. Replacing a fan is a routine service call for a certified mitigator.
What should I do if a contractor tears my crawl space membrane?
Have it patched and resealed with compatible tape or sealant, then check the manometer. A large tear can let crawl space air bypass the suction and raise radon levels.
Can I turn the system off in summer?
It's not recommended. Radon can enter year-round, and a system that's switched off provides no protection. It's designed to run continuously.