Will a radon mitigation system increase my electric bill?

The arithmetic

Residential radon fans are small, typically drawing something in the range of a few dozen watts up to around ninety depending on the model and how much resistance the system presents. Running continuously, that lands most households at a few dollars a month on the electricity line. It is a real cost and a small one, and it is predictable in a way most household loads are not.

Fan sizing is what moves the number, and bigger is not better. A unit chosen to overcome the actual resistance of the system draws less and runs quieter than one oversized on the theory that more suction must help.

Why it has to run all the time

The obvious saving is a timer, and it does not work. The system holds the space under the slab at lower pressure than the basement, and that difference is what keeps flow running the correct direction at every opening. Switch the fan off and the pressure equalises within a short time, entry resumes, and the level climbs back.

Cycling it also undermines the thing that makes the result trustworthy. A house whose system runs intermittently has no stable level to measure, and a confirming test taken during an on period says nothing about the rest of the week.

The offset people do not expect

Installation includes closing the openings that were carrying the most gas, and those same openings were carrying conditioned air out of the house. Sealing a sump pit lid, the slab-to-wall joint, and the gaps around penetrations reduces the uncontrolled air exchange that was already costing money on heating and cooling.

The offset is rarely enough to cancel the fan outright, and it is real. For most houses the honest summary is that the whole thing is close to a wash against existing leakage, with the fan itself too small a load to notice against seasonal variation in a utility bill.

Still deciding what to do about a reading? The testing page covers how a measurement is taken, and what a system costs breaks the ranges down by method. If you got here from a map or a ZIP-code lookup, what Ohio's radon maps show explains what those averages are actually measuring.