The new fan hums, the pipe is labelled and the installer has packed up. Those are good things to have in place. The answer to whether the radon level came down still comes from a radon measurement.
A system indicator can help you notice a change in operation. It is not an indoor radon reading. Treat equipment checks and radon testing as two different parts of owning the system, just as a furnace running does not tell you the temperature in every bedroom.
Leave installation day with a usable record
Ask the installer for the system description, commissioning findings, operating instructions and contact details. Identify the fan, any alarm or pressure indicator, and the normal condition you should expect to see. Photograph the indicator in that documented condition so you have a comparison later.
| Check | What it tells you | What to keep |
|---|---|---|
| System indicator and alarm | Whether operating conditions match the installer instructions | Normal reference and service contact |
| Long-term radon measurement | Radon concentration over the measurement period | Location, dates and report |
| Post-renovation review | Whether work affects system integrity or testing needs | Work details and professional advice |
Have the installer explain what to do after an alarm, power interruption or changed reading. Do not adjust valves, disconnect piping or switch the system off to save electricity without appropriate advice. Arrange service when the system is not operating as intended, and keep its electrical supply protected from accidental unplugging.
If the sump cover forms part of the sealed system, ask how pump access and maintenance are handled. Our sealed sump-lid guide is useful before someone removes a cover and leaves its seals damaged.
Confirm results with the current measurement protocol
Health Canada: guide for radon measurements in residential dwellings recommends a long-term home test with at least 91 days during the heating season. A test can begin at any time of year; plan its duration accordingly. Follow the guide's placement instructions and your provider's directions. A brief commissioning reading does not replace that assessment. If a test includes fewer than 91 heating-season days and returns below 200 Bq/m³, retest during the next heating season. An above-guideline result from a test lasting at least 91 days warrants action even outside the heating season; do not postpone it just to repeat the test.
Ask who supplies the follow-up detector, where it will be placed, who submits it and who receives the result. Put those responsibilities in the handover rather than assuming the installer or homeowner has the other half covered. Keep the start and end dates, location and report together.
Use the result to discuss whether further adjustment or mitigation work is needed. Do not interpret a reduction alone as sufficient without considering the resulting level and current Health Canada guidance. The goal is to reduce exposure, not simply to produce a smaller number than the first test.
Retest after meaningful changes
Health Canada recommends a follow-up test in the next heating season after a radon mitigation system is installed. It also recommends retesting after relevant renovations, damage or changes to the lowest lived-in level. Homes with active mitigation systems should be retested every five years. That periodic interval is not a reason to ignore a system fault between tests.
Basement renovation can alter the conditions you originally tested. New openings in the slab, work around a sump or changes to how the basement is occupied should be discussed with the mitigation professional. Keep the radon system on the project drawings so it does not become an unexplained pipe for another trade to relocate.
If you are still deciding whether to finish the basement, read testing before basement finishing. Testing and mitigation are easier to coordinate when slab and wall access have not yet been hidden by the new room.
Keep a simple system log
A useful log has four columns: date, observation, action and report location. Record service visits, fan replacement, alarms, major renovations and radon test results. There is no need to turn this into a daily spreadsheet unless the system instructions call for particular monitoring.
For example, after a basement plumbing project, record what was opened, how the sealing was restored and the advice received about follow-up measurement. That is more helpful than trying to remember, several years later, whether the pipe work happened before or after the last detector was used.
If the house is sold, include the system information and measurement history with the handover documents. The next owner needs to know why the fan stays on and what a normal indicator looks like. A quietly operating system is easy to overlook precisely because it is doing its job in the background.