A frozen radon exhaust the fan can look fine and do nothing
The air leaving the pipe is moist. In a hard frost, a collar of ice can form at the outlet, especially if it is short or poorly cleared. Airflow drops. The U-tube or manometer, which had been showing suction, moves toward zero.
Clear the outlet if you can reach it without putting yourself at risk on the roof. If the blockage returns every night, the installer lengthens or insulates the exhaust. Do not switch the fan off “until it warms up.” Snow. A stopped fan.
The 4-day test gives a first reading. The 91-day test covers the three-month minimum Health Canada asks for. Both are $59 before tax: shipping, return and the laboratory are included, taxes extra. The PDF report is sent within 2 business days after the laboratory receives the detector.
Above 200 Bq/m³, mitigation is confirmed with a quote. Gaz Radon is C-NRPP certified for measurement and mitigation.
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