Radon Mitigation System Inspection: What to Check Before Calling a Contractor

Before calling a certified mitigator for an inspection or service visit — which costs $150–$300 — there are several things a homeowner can check in 30 minutes that will either resolve the issue, inform the contractor call with specific findings, or confirm that professional service is genuinely needed. This checklist covers the complete self-inspection sequence for an ASD radon mitigation system, organized by location in the home.

What You Need

A flashlight or phone light
A stepladder for attic access (if the fan is in the attic)
A smartphone to photograph anything unusual
This checklist

No specialized tools are required for this inspection. Everything on this list is assessable by a homeowner with basic observational ability and safe access to the fan location.

Step 1: Check the Manometer (Living Space — 30 Seconds)

Find the U-tube manometer — the liquid-filled gauge mounted on the visible portion of the riser pipe, typically in the basement, utility room, or closet. Observe the liquid level:

✅ Liquid displaced (one side higher): Fan is generating negative pressure. System is operating. Continue checklist to confirm no other issues.
❌ Liquid level (equal on both sides): Fan is not generating suction. Proceed to Step 2 before calling a contractor — there may be a simple fix.

Step 2: If Manometer Shows No Pressure — Check Power

Go to the fan location (attic, exterior, or garage). Is the fan running? Can you hear or feel airflow from the discharge?
If the fan appears not to be running: check the outlet by plugging in a lamp or phone charger. Is the outlet live?
Check the circuit breaker panel for the circuit supplying the fan outlet — is any breaker tripped?
If power is confirmed at the outlet but the fan is not running: the fan has likely failed. This requires professional fan replacement — there is no user-serviceable fix for a burned-out fan motor.
If the outlet has no power (breaker tripped): reset the breaker. If it trips again immediately, there is a wiring issue — do not continue resetting; contact an electrician.

Step 3: Fan Location Inspection

Access the fan location safely. Bring your flashlight.

✅ Fan housing: no visible cracks or damage
❌ Fan housing: cracks visible — fan must be replaced regardless of whether it still runs (cracked housing discharges radon at the fan location)
✅ Inlet pipe connection (from below): secure, no gaps, no sign of separation
❌ Inlet connection: loose or separated — this is an air leak that reduces fan efficiency; pipe must be reconnected and re-cemented
✅ Outlet pipe connection (to discharge): secure, no gaps
❌ Outlet connection: loose or separated — reconnect and re-cement
✅ Fan mounting: stable, not in contact with adjacent framing
❌ Fan touching adjacent framing: add rubber isolation pad or adjust mounting
✅ Electrical connection: undamaged power cord or secure hardwired connection
❌ Damaged power cord: do not operate — contact an electrician or the original installer

Step 4: Discharge Cap Inspection

✅ Cap is intact and undamaged
❌ Cap is cracked, missing, or severely corroded — replace the cap; this is a DIY-accessible fix ($15–$30 for a standard 3″ PVC weatherproof cap)
✅ Cap opening is unobstructed — no bird nesting, debris, or ice visible
❌ Cap is obstructed — clear the obstruction. For ice: this is a cold-climate common issue; wrapping the pipe in heat tape near the cap can prevent recurrence.
✅ Pipe below the cap is secure and has not shifted in wind or from thermal movement
❌ Pipe has shifted or become unsecured — restrain with appropriate pipe strap or bracket

Step 5: Visible Riser Pipe Inspection

✅ Pipe is physically intact — no visible cracks or impact damage
❌ Pipe is cracked or damaged — section must be replaced by a professional
✅ All visible joints show cemented connections (purple/gray ring visible at each joint)
❌ Joints appear dry-fitted (no cement ring visible) — these are air leaks that must be re-cemented; this is professional work if in a hard-to-access location
✅ Pipe is strapped to framing every 4–6 feet
❌ Loose or missing pipe straps — tighten or add straps; this is a DIY-accessible fix
✅ Required AARST warning label is present and legible
❌ Label is missing or unreadable — obtain a replacement label from a radon supply distributor or your original installer

Step 6: Suction Point and Slab Inspection

✅ Core hole seal around riser pipe at slab is intact — no gaps or crumbling
❌ Core hole seal is deteriorated or gapped — reseal with hydraulic cement (DIY-accessible)
✅ No new visible slab cracks since last inspection
❌ New slab cracks visible — photograph and document; seal wide cracks with polyurethane caulk; schedule a retest to confirm these new pathways are not affecting radon levels
✅ Expansion joints and control joints show intact sealant
❌ Sealant is cracked, pulled away, or missing in joints — reapply polyurethane caulk (DIY-accessible)
✅ Sump pit (if present) has an airtight lid that is secure
❌ Sump lid is loose, damaged, or missing — this is a significant radon bypass pathway; replace or repair the sump lid immediately

Interpreting Your Inspection Results

All ✅ — System Appears Intact

If all checkpoints pass and the manometer shows displaced fluid, the system is operating normally. If you are conducting this inspection because of elevated radon test results, a professional diagnostic visit is still advisable — some performance issues (fan approaching end of life, partial suction field coverage) are not apparent from visual inspection alone.

One or More ❌ — Action Required

For DIY-accessible fixes (pipe straps, sealant, sump lid, discharge cap): address these immediately. For items requiring professional work (cracked housing, separated pipe joints in inaccessible locations, failed fan, hardwired electrical issues): contact your original installer under the workmanship warranty if within the warranty period, or any certified mitigator for an out-of-warranty service call.

Frequently Asked Questions

How do I know if my radon mitigation system needs service?

Run through this inspection checklist: check the manometer (displaced fluid = running), inspect the fan housing and pipe connections, confirm the discharge cap is unobstructed, and examine the visible pipe and slab sealing. If all items pass and the manometer shows the system is running, conduct a 48-hour radon test to confirm actual performance. If the test shows elevated levels despite the system appearing operational, schedule a professional diagnostic visit.

Can I do this inspection myself or do I need a professional?

This entire inspection is accessible to any homeowner comfortable with attic access and basic observation. No specialized tools or training are required. Professional involvement is needed only when the inspection reveals issues that require construction work (re-cementing separated pipe joints in inaccessible locations, fan replacement, electrical repairs) or when the visual inspection passes but elevated radon levels require deeper diagnostic investigation.

What is the most important thing to check on my radon system?

The U-tube manometer — check it first, check it monthly. A displaced liquid column tells you in 5 seconds that the fan is running and generating negative pressure. Everything else on this checklist refines your understanding of system integrity and performance, but the manometer is the primary indicator that can reveal the most critical failure mode (fan stopped) without any tools or expertise.