Can a heat recovery ventilator (HRV) fix a radon problem?

Dilution versus interception

The two approaches work at different points in the problem. An active sub-slab system intercepts soil gas before it enters, by holding the ground beneath the floor at lower pressure than the room so that flow reverses at every opening. An HRV lets the gas in exactly as before and then thins it with outdoor air, recovering some of the heat on the way through.

That difference sets a ceiling on what ventilation can achieve. Halving a reading takes roughly doubling the air-change rate, and each further halving costs another doubling. A house starting well above the threshold runs out of practical ventilation capacity long before it runs out of radon.

Where an HRV is genuinely the right call

There are real cases. A building with no accessible slab to work under, such as certain slab-on-grade constructions or an upper-floor unit in a larger structure, may leave no suction point to create. Some tightly built modern houses need mechanical ventilation for humidity and indoor air quality regardless, and the radon reduction arrives as a secondary benefit of equipment being installed anyway.

There is also the modest-reading case: a house sitting in the range where action is a judgement call rather than a recommendation, where an HRV that a homeowner wanted for other reasons may bring it comfortably down. That is a different proposition from relying on one to solve a high reading.

The practical drawbacks worth knowing

An HRV runs continuously and recovers only part of the heat it exchanges, so it carries an ongoing energy penalty that a radon fan does not. It also needs balancing: an unbalanced unit that exhausts more than it supplies leaves the house at lower pressure than the ground, which pulls harder on the foundation and can push a reading up rather than down.

And it requires maintenance to keep performing. Filters and cores need cleaning on a schedule, and effectiveness declines quietly when that lapses. A sub-slab fan, by contrast, has one moving part and a gauge that shows at a glance whether it is still working.

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.