How do you maintain a radon mitigation system?
Updated August 2026
A radon system is nearly maintenance-free, so the whole job is a monthly 10-second look at the manometer (the little U-shaped gauge on the pipe) and a radon retest every 2 years. If the two fluid columns sit level with each other, the fan has stopped and radon is no longer being pulled out from under the slab. The inline fan is the only moving part; it runs 24/7 and lasts 5 to 10 years, then costs $150 to $300 for the fan plus install. EPA's action level is 4 pCi/L. See retest timing and the fan check.
| Task | Interval | Effort |
|---|---|---|
| Glance at the manometer U-tube on the pipe | Monthly | 10 sec · DIY |
| Confirm the two fluid columns sit at different heights | Monthly | 10 sec · DIY |
| Listen that the inline fan is still humming | Monthly | 10 sec · DIY |
| Task | Interval | Effort |
|---|---|---|
| Retest radon with a kit or a pro | Every 2 years | $15–30 kit / $150 pro |
| Retest after finishing a basement or new HVAC | After changes | $15–150 |
| Task | Interval | Effort |
|---|---|---|
| Replace the mitigation fan | 5–10 years | $150–300 + install |
| Reseal sump covers and slab penetrations | As needed | $10–50 · DIY |
What neglect costs
Radon is invisible, so the only way a stalled fan shows up is on a test, and by then you have been breathing it. Radon is a leading cause of lung cancer among non-smokers, and a mitigation system that quietly quits can let levels climb back over the 4 pCi/L action line within days. The fix is almost insultingly cheap next to the stakes: a replacement fan is $150 to $300, a DIY retest kit is $15 to $30, and a professional test is around $150. A manometer you glance at each month is free. Skipping the retest is the classic false economy.
Leave these to a pro
Fan replacement is the one job most people hand off: the fan usually lives in the attic or outside on the vent stack, is wired to a dedicated circuit, and must be sealed airtight when reinstalled, so a radon contractor charges $300 to $600 all in for the $150 to $300 part plus labor. A pro is also worth it for the confirmatory retest and for diagnosing a system that reads high even with the fan running, which can mean adding a new suction point ($500 to $1,500). The monthly manometer glance and swapping in a DIY test kit stay on your side.
This whole checklist ships as reminders in OnOtto: every task above, on the right schedule for your home, snooze-proof.
Load this checklist as remindersFrequently asked questions
How do I read the manometer on my radon pipe?
The manometer is the clear U-shaped tube taped to the vent pipe, partly filled with colored fluid. When the fan is pulling suction, the two columns sit at different heights, often an inch or two apart. If they have leveled out to the same height, the fan has stopped or the system has lost suction, and radon is no longer being vented. Many systems mark a normal range on the gauge; snap a photo when it is working so you have a reference to compare against.
How often should I retest radon if I have a system?
Every two years is the standard, plus any time after a big change: a finished basement, new HVAC or ductwork, foundation work, or an addition, all of which can shift airflow and radon entry. A short-term DIY kit is $15 to $30 and a pro test around $150. If a reading comes back at or above the 4 pCi/L action level even with the fan running, call your radon contractor, because the system needs an adjustment or a stronger fan.
Does the radon fan need to run all the time?
Yes, continuously, 24 hours a day, year-round. The fan holds constant negative pressure under the slab so soil gas never gets a chance to enter, and cycling it off would let radon rebuild within hours. It draws roughly the power of a low-watt light bulb, so the running cost is minor, often $5 to $15 a month. Never switch it off to save energy or quiet the house; if it has grown noisy, that is a sign the fan bearing is wearing out.