Radon Mitigation System Maintenance Guide

A radon mitigation system is a simple machine — typically a fan, a pipe, and some sealant — but its job is critical. Because radon is invisible and odorless, a failing system gives no obvious warning signs. Regular maintenance and scheduled retesting are the only way to confirm your system is still doing its job.

How Often to Test After Installation

The EPA recommends testing your radon levels every two years after a mitigation system is installed, and any time you make significant changes to your home that could affect foundation integrity or air circulation — adding living space below grade, renovating a crawl space, or making changes near the slab.

You should also retest after any event that could affect your system:

• The system indicator shows no pressure differential
• You hear unusual noise from the fan
• Power outages or surges that may have affected the fan
• After buying a home with an existing system (don’t assume the previous owner tested)

Long-term charcoal canister tests (48–96 hours) or continuous electronic monitors give the most reliable readings. Short-term tests are acceptable for initial screening but should be followed up with a longer test if results are near the action level.

Checking the System Indicator (U-Tube Manometer)

Most active radon systems include a visual indicator — typically a small plastic U-tube filled with colored fluid mounted on the pipe near where it enters the wall or ceiling. This manometer shows whether the fan is creating negative pressure in the pipe.

When the system is working correctly:

• The fluid in one arm of the U-tube sits lower than the other, indicating suction
• The difference in fluid levels is typically 0.5 to 2 inches

If both arms of the U-tube are level — equal fluid height on both sides — the system is not creating suction. This is the most common sign of fan failure.

Check your system indicator monthly. It takes less than a minute and gives immediate feedback on whether the fan is running and pulling pressure. Some systems use a simple flag or gauge instead of a manometer — confirm with your installer what indicator was installed and how to read it.

Signs the Fan Is Failing

Radon fans are designed for continuous operation and typically last 10 to 15 years, though some fail earlier due to moisture, power surges, or bearing wear.

Warning signs that your fan may be failing or has already failed:

• U-tube indicator shows no pressure differential. This is the clearest mechanical sign.
• Unusual noise. A healthy radon fan produces a low, steady hum. Rattling, grinding, squealing, or intermittent sound indicates mechanical problems.
• Fan is warm or hot to the touch. Excess heat can indicate a struggling motor.
• Fan is completely silent. In a quiet basement or utility room, you should be able to hear a faint hum from an operating fan. Total silence may mean it’s off.
• Elevated retest results. A routine retest showing radon levels have climbed back above pre-mitigation levels is the most definitive evidence that something has changed — whether that’s a failed fan, a new entry pathway, or a change in foundation conditions.

When to Call a Professional

Contact a licensed radon mitigation contractor if:

• Your system indicator shows no pressure differential
• You suspect the fan has failed
• Post-mitigation retest results are at or above 4 pCi/L
• You need to modify the system for a renovation project
• Your warranty requires periodic professional inspection (some contractors require this to maintain warranty coverage)

Fan replacement is a straightforward job for a qualified contractor — usually completed in under two hours. The cost typically runs $200 to $500 depending on fan model and accessibility.

Annual Maintenance Checklist

A short annual inspection helps catch problems early:

• Check the U-tube or pressure indicator. Confirm fluid levels show suction. Note any change from previous checks.
• Listen for the fan. Stand near the fan housing and confirm a steady, consistent hum.
• Inspect visible pipe sections. Look for disconnected joints, cracks in the PVC, or pulled fittings — especially near the fan.
• Check exterior vent. Confirm the exterior pipe exit is clear of debris, bird nests, or ice dams.
• Inspect slab sealant. Areas around the suction point penetration and any sealed cracks should remain intact. If sealant has cracked or pulled away, contact your contractor.
• Review your test date. If it’s been more than two years since your last radon test, schedule one.

Keeping a simple log — date checked, indicator reading, notes — takes minutes and gives you documentation if you ever sell the home or need warranty service. Find local radon mitigation contractors in your area if your system needs inspection or repair.