A mitigation system has one moving part and one gauge, and most owners never learn either. Then the fan dies quietly some February and the house spends a season at pre-mitigation levels with nobody the wiser. Five minutes of knowledge prevents all of that.
What normal is
A healthy fan hums softly, continuously, forever — it never cycles like a furnace. Standing near the pipe you may hear faint airflow; from the living space you should hear nothing.
Wisconsin winters add quirks: brief gurgles after rain or thaw as condensation drains back down the pipe are normal. A persistent gurgle means water pooling in a low spot of a badly sloped run — fixable, and worth fixing before it throttles the airflow.
The manometer in one paragraph
The u-tube on the riser holds colored fluid at two levels. Uneven equals suction equals working. Level equals no vacuum equals dead system — check plug, switch, breaker, then call. Put a tape mark at the normal level and any drift becomes obvious at a glance.
Sounds that mean the fan is done
Grinding, rattling, or a wobble you can feel through the pipe are bearing failure announcing itself; fans last five to ten years and rarely die politely. Repeated breaker trips and a slowly sinking manometer tell the same story in different ways.
Replacement is a same-day swap on the existing pipe, not a new system. Retest after the swap to confirm the number returned to normal.
The whole maintenance calendar
Monthly: glance at the manometer as you walk past. Yearly: thirty seconds listening at the fan, a look at the visible pipe and roof discharge. Every two years: retest and file the report. That is the entire cost of ownership — less attention than a furnace filter, protecting the air your family breathes all winter.
If you remember one thing
Tape-mark the manometer today and glance at it monthly. Every failure mode a radon system has — dead fan, leak, blocked pipe — shows up as those two fluid columns drifting toward level, usually long before any sound does.
It is the cheapest early-warning system in your house, and it is already installed.
