Installing a Radon Mitigation Fan, Your Step-by-Step Homeowner Guide

by Suncourt Inc. August 28, 2026

Your home could be sitting on an EPA action-level radon reading right now, and you would have no way to know without a test. Once testing confirms an elevated radon level, one of the most common solutions is an active soil depressurization system, which uses a continuously operating fan to draw radon-containing soil gas from beneath the home and vent it outdoors.

We walk through exactly how that fan gets installed, piece by piece, so you know what a proper job looks like whether you are hiring it out or handling part of it yourself.

What a Radon Mitigation Fan Actually Does

Radon is a radioactive gas that forms as uranium breaks down in soil and rock, and it finds its way into homes through foundation cracks, sump pits, and gaps around pipes. You cannot see it, smell it, or taste it, which is exactly why the EPA identifies it as the second leading cause of lung cancer in the United States, tied to an estimated 21,000 deaths a year.

A radon mitigation fan is the working component of a sub-slab depressurization system, the method most commonly used to fix elevated readings across the country. The fan sits on a length of PVC pipe that runs from a suction point beneath the slab, through the home or along an exterior wall, and out above the roofline. Once it is running, the fan creates negative pressure under the foundation. It pulls soil gas into the pipe before it ever has a chance to enter your living space, then releases it into the outdoor air where it disperses safely.

Suncourt's Centrax fan kits, the RDN04 and RDN04-3, are built around a centrifugal impeller designed specifically for this kind of continuous suction work, and both are engineered and assembled in the USA by Suncourt, a family-owned manufacturer based in Durant, Iowa.

Note: In homes with slab or basement foundations, the fan typically creates negative pressure beneath the slab. Other foundation types, including crawl spaces, may require a different soil-gas collection configuration.

Signs Your Home Needs a Mitigation Fan

The only reliable sign that your home needs a mitigation fan is a confirmed test result. Radon levels shift with the seasons, the soil under your specific lot, and even how tightly your windows and doors seal, so two homes on the same street can post very different numbers.

A short-term test measures your home over a few days and gives you a fast read, while a long-term test runs for at least three months and produces a more accurate average. Many homeowners run a short-term test first, especially during a real estate transaction, then confirm elevated results with a second test before committing to a full system. Our radon testing and mitigation overview breaks down both testing methods in more detail.

Once a confirmed result is 4.0 pCi/L or higher, EPA recommends taking action to reduce the home's radon level. A qualified radon professional can determine whether active soil depressurization and a mitigation fan are the right approach for the home's foundation and layout.

Tools and Materials to Gather First

4-inch or 3-inch PVC pipe, elbows, and couplings sized to match your fan kit.
PVC primer and cement for solvent-welded PVC joints, as required by the system design.
A radon mitigation fan kit that includes anti-vibration couplers, such as the RDN04 or RDN04-3.
Mounting brackets or a pipe strap rated to hold the fan's weight.
A manometer or air pressure indicator to confirm suction once the system is live.
An exterior vent cap or termination fitting rated for the roofline or wall penetration.
Urethane sealant or hydraulic cement for slab cracks, sump lids, and pipe penetrations.
A drill, a pipe cutter or reciprocating saw, and a stepladder for attic or roofline access.
Electrical wiring and disconnect components required by the manufacturer's instructions and applicable local electrical code.
A system label to post near the vent pipe and electrical panel identifying it as a radon mitigation system.

Step by Step, Installing a Radon Mitigation Fan

Test first. If an initial short-term test is 4.0 pCi/L or higher, follow EPA guidance for a confirmation measurement before making a mitigation decision. EPA recommends fixing at 4.0 pCi/L or above and considering mitigation between 2 and 4 pCi/L.
Choose the suction point. Depending on the home, a system may draw from a suction pit cored through the slab, an existing drain-tile system, or a properly sealed sump configuration. The correct location and number of suction points depend on sub-slab airflow and the home's construction.
Seal accessible cracks, sump lids, and penetrations that could allow soil gas or conditioned indoor air to bypass the system. Floor drains and other functional openings should be addressed using an appropriate radon-resistant method rather than automatically sealed shut.
Route the vent piping so the radon exhaust terminates outdoors above the roof in accordance with current radon mitigation standards and applicable local requirements. The discharge must also be positioned far enough from windows, doors, air intakes, and other openings to reduce the risk of radon re-entering the building.
Choose an approved fan location outside conditioned living space, such as an appropriate attic location or exterior installation. Both configurations are shown on the RDN04 product page, and we cover the tradeoffs in the next section.
Mount the fan with the anti-vibration couplers supplied along with the fan. Slide the anti-vibration couplers onto the pipe on both sides of the fan, then secure the fan body to a bracket or strap so the pipe joints are not carrying the fan's full weight.
Have the fan wired according to Suncourt's installation instructions and applicable electrical code. Local requirements may govern the circuit, disconnect, wiring method, and who is permitted to perform the work.
Add a manometer or air pressure indicator to the vent stack so you, and any future home inspector, can confirm the fan is running under suction at a glance.
Cap and label the vent pipe above the roofline, and post a system label near the electrical panel and the pipe itself identifying it as an active radon mitigation system. Measures must be taken to stop water, debris, and wildlife from traveling down the exhaust pipe and reaching the fan; water or obstruction damage can void the warranty.
Retest after installation. EPA recommends a post-mitigation measurement within 30 days after the system begins operating, but not sooner than 24 hours after startup. Continue to retest periodically, including about every two years, to confirm radon remains low.

Indoor Attic Placement vs Outdoor Placement

Attic Placement

Keeps the fan protected from direct weather exposure.
Requires solid blocking or strapping so the fan is not just hanging on the pipe.
Needs the vent pipe sealed tight anywhere it passes through conditioned living space.

Outdoor Placement

Keeps the fan and its motor completely outside the home's conditioned space
Simplifies future service, since there is no attic access needed to reach the fan
Calls for a shielded or elevated mount so rain, debris, and wildlife cannot reach the housing

Both Suncourt kits use the same 4-inch Centrax centrifugal fan. The RDN04 includes two 4"-to-4" anti-vibration couplers, while the RDN04-3 includes two 4"-to-3" couplers for use with 3-inch piping. Brackets, piping, manometers, and other system components should not be described as included unless separately confirmed.

Note: For exterior installations, follow Suncourt's requirements for keeping water, debris, and wildlife from entering the exhaust pipe and reaching the fan. The fan is rated for outdoor operation, but damage caused by water or internal obstructions is excluded from warranty coverage under the supplied product warning.

Mistakes That Weaken a Radon System

Failing to properly address slab openings, sump lids, drains, and penetrations that can allow soil gas or unwanted air leakage.
Skipping the anti-vibration couplers, which lets fan noise and vibration travel straight into the framing
Terminating the vent pipe too close to a window, door, or air intake
Wiring the fan to a switched outlet that someone can accidentally turn off
Mounting the fan so its full weight rests on the pipe joints instead of a bracket or strap
Skipping the post-install retest, which is the only way to confirm the system actually brought levels down

When to Call a Certified Radon Professional

The EPA's Consumer's Guide to Radon Reduction recommends a qualified contractor for full system design, since a poorly placed suction point can fail to lower levels or pull conditioned air instead of soil gas. Homeowners who are comfortable with PVC work and basic electrical wiring can often handle a straightforward fan swap on an existing system, but designing a new suction point, coring a slab, or routing a vent pipe through multiple floors is a job worth handing to someone trained for it.

Find a qualified radon mitigation professional through your state radon program or an EPA-recognized national credentialing program such as NRPP or NRSB, subject to your state's requirements. If you have questions about which Suncourt fan kit fits your setup, our team is reachable through the Suncourt contact page.

Keeping Your Fan Running for the Long Haul

A properly installed radon mitigation fan runs continuously. Check the manometer or other system-failure indicator regularly to confirm the system remains under suction. A sudden change in motor pitch, a louder hum, or a manometer reading that drops to zero all point to a problem worth investigating right away.

Replacing a fan in an existing, correctly designed system may be more straightforward than installing a new mitigation system, but homeowners should first check Suncourt's instructions, local electrical/building requirements, and any state radon rules. New suction points, system redesign, and complex vent routing should be handled by a qualified radon mitigation professional.

Suncourt's RDN04 and RDN04-3 kits carry a 5-year limited warranty, and pairing that coverage with a retest every 2 years is the simplest way to confirm your system is still doing its job years after installation.

FAQs

How long does it take to install a radon mitigation fan?

Installation time depends on whether you're replacing a fan in an existing system or building a complete mitigation system. A full residential mitigation system can often be installed in about a day, although foundation type, piping, electrical work, and access can change the timeline.

Can a homeowner install a radon mitigation fan without a contractor?

Homeowners with PVC and electrical experience can install or replace a fan on an existing vent pipe. However, EPA advises consumers to use qualified radon professionals and check state requirements. It is also important to check the manufacturer guidelines before attempting an installation.

Where should the radon fan be located?

The fan should sit outside the conditioned living space, either in an attic above an insulated ceiling or mounted on an exterior wall, never inside a basement or crawl space, so that any leak at a pipe joint vents outdoors rather than into the home.

How do I know the fan is still working?

Check the system's manometer or warning device against its normal operating reading. A zero reading or significant change can indicate that the system is not operating as expected and should be investigated.

How much does a radon mitigation fan kit cost?

Suncourt's current RDN04 and RDN04-3 kits include the 4-inch Centrax centrifugal fan and two anti-vibration PVC couplers. Other components required for a complete radon mitigation system (including vent piping, supports, a system-failure indicator/manometer, sealing materials, and electrical components) are not listed as included with these kits. Current product pricing is available on the individual product pages.

Breathe Easier With a Properly Installed Radon Fan

Installing a radon mitigation fan comes down to a handful of details done right: a sealed slab, a properly routed pipe, a securely mounted fan, and a retest that proves the system works. Get those right, and the fan runs quietly in the background for years, pulling radon-containing soil gas from beneath the home before it can enter the living space.

If you are ready to start the project, Suncourt's RDN04 and RDN04-3 Centrax radon mitigation fan kits are MET Listed, engineered and assembled in the USA, and backed by a 5-year limited warranty. Reach out through our contact page or call us if you want help picking the right kit for your home.