When the gauge goes flat, the fan comes first
Radon fans run around the clock for years and eventually wear out. A repair ends with a working gauge and a retest.
The systems nobody thinks about — until the gauge goes flat
Radon mitigation took off in Pennsylvania in the late 1980s, and the suburbs around Harrisburg have been accumulating systems ever since. The split-levels off Linglestown Road, the 1990s colonials in Hampden and Lower Paxton townships. Thousands of those homes have a pipe in the basement and a fan that has been running, without a day off, for ten or twenty years.
Fans don’t last forever. Most wear out on a roughly decade-long cycle, which means a wave of local systems is quietly due. And plenty of current owners inherited their system with the house: no manual, no explanation, no idea what the little tube of fluid on the pipe is for.
This page covers that whole situation: figuring out what your system is, replacing a fan that’s done, and getting the gauge to say something true again.
Sound familiar?
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The fan has gone silent
No hum at the pipe usually means no suction below the slab.
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Loud, rattling, or grinding
Bearings on the way out tend to announce themselves before they quit.
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The gauge fluid sits level
Equal fluid in the U-tube typically means the system has stopped pulling.
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The installer is long gone
Plenty of local systems outlived the company that put them in.
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You inherited a mystery system
Bought a house with pipes and a fan nobody ever explained.
Reading the gauge on your pipe
That small U-shaped tube on your radon pipe is a manometer, and it’s simpler than it looks. It holds colored fluid, and the fan’s suction pulls one side of the fluid up.
So the check takes five seconds. If the two fluid columns sit at different heights, the fan is pulling. That’s what you want. If the fluid sits dead level on both sides, there’s no suction. The fan has likely stopped, tripped a breaker, or come unplugged.
A few honest caveats. The gauge only reports suction, not radon. A pulling fan on a cracked pipe, or a system that was never designed right, can show a healthy gauge over a basement that still tests high. And a gauge can misread if the fluid has evaporated over the years. That’s why the gauge is a screening habit, not a verdict. The verdict comes from a radon test.
Make the glance a routine, the way you check a smoke-detector light. For the fuller walkthrough (sounds, discharge pipes, and when to escalate), see is my radon system working?
What a repair visit typically covers
A system-repair call is mostly detective work, and it usually runs wider than the fan itself. The fan gets assessed and, if it’s done, replaced with one matched to the system’s airflow needs, not just whatever’s on the shelf. The pipe run gets looked over for cracked couplings, failed seals, and joints that have worked loose through years of vibration. The gauge gets checked and refilled or replaced so it reads honestly again. If the suction point or sealing around the slab has degraded, that comes up too.
What can’t be promised from a webpage: which fan, what parts, or what your particular system needs. A repair scope follows from looking at the system, and system designs vary house to house.
One step matters after any repair, and it’s the one that’s easiest to skip: the retest. A new fan proves the system pulls; only a radon test proves the house is back below where it should be. Our radon testing guide covers how that test runs, or you can have testing scheduled along with the repair.
Gauge looks wrong or the fan's gone quiet? Have it looked at.
Frequently Asked Questions
How long do radon fans last?
On the order of a decade, in industry experience. Some quit sooner, some run fifteen years. They work around the clock, every day, so wear is a when, not an if. The gauge going flat is usually how owners find out.
Can I replace the fan myself?
Some handy owners do, but there are real catches. The fan is wired into the house, the pipe couplings have to reseal airtight, and the replacement needs to match the system's airflow design. A wrong-sized fan can underperform quietly for years. If any of that gives you pause, it's a quick professional job.
My system hums louder than it used to. Is that a problem?
A change in sound is worth attention even when the gauge still shows suction. New rattles or grinding often mean the fan's bearings are wearing out, and vibration can also point at loose mounts or pipe contact. Catching it early usually means a planned swap instead of a dead system discovered months later.
What does the U-tube gauge actually tell me?
One thing only: whether the fan is creating suction in the pipe. Unequal fluid levels typically mean it's pulling; level fluid typically means it isn't. It says nothing about the radon level in your air. Only a test measures that.