A note before you read. This is general consumer information for Canadian homeowners, buyers, sellers, landlords, and renters, drawn from publicly available Health Canada and Canadian National Radon Proficiency Program (C-NRPP) sources. It is not medical, legal, or warranty advice. Radon results are reported against the Health Canada guideline of 200 Bq/m³; RadonTest.ca coordinates testing logistics and does not interpret individual results or provide health assessments. Whether a mitigation system is keeping your home below the guideline can only be confirmed by a completed radon test — not by a gauge — and questions about a malfunctioning system should go to a C-NRPP-certified mitigation professional.
Key facts at a glance
- The U-tube manometer on your radon pipe shows the FAN is moving air — not your radon level. It is a fan/pressure indicator, not a radon meter.
- Only a radon test confirms you are below 200 Bq/m³. No gauge, light, or alarm measures the radon concentration in your home; a test does.
- The fan must run continuously. It is never switched off — that's how the system keeps soil gas out of your living space.
- Radon fans typically last about 5 to 10 or more years. When one wears out, replacement runs roughly $200–$300.
- Health Canada recommends a long-term confirmation test after mitigation — and then re-checking the system with a long-term test within two years of activation, and every five years afterward.
- A manometer can read "fine" while the level is still elevated if the system is under-sized or conditions in the home have changed. The gauge and the test answer two different questions.
The manometer tells you the fan works — not your radon level
If you have a mitigation system, you almost certainly have a small clear gauge mounted on the radon pipe, usually near the fan or where the pipe passes through a wall. It is a U-tube manometer: a U-shaped tube partly filled with coloured liquid. It is the single most useful at-a-glance check you have — as long as you understand exactly what it does and doesn't tell you.
What it measures. The manometer reads the suction (pressure difference) the system is pulling on the soil beneath your home. Read it like this:
- The two liquid columns sit at different heights → the system is pulling suction. The fan is moving air and the system is doing its mechanical job. This is what you want to see.
- The two columns sit at equal heights (level with each other) → the fan likely isn't working. No pressure difference means no suction — a sign the fan has failed, lost power, or the pipe is blocked or leaking.
That's the whole reading. Health Canada describes this gauge as a way to tell that the system is operating and the fan is moving air — in other words, it is a fan/pressure indicator.
The critical limit — read this twice. The manometer does not measure the radon concentration in your home. It cannot. It only tells you the fan is creating suction; it says nothing about how much radon is left in your living space. A system can pull good suction and still leave your home above 200 Bq/m³ if the fan is under-sized for the house, if a suction point isn't reaching part of the foundation, or if conditions have changed since it was installed. The only thing that measures your actual radon level is a radon test. Keep those two ideas separate and you'll never be misled by a healthy-looking gauge.
Quick checks you can do
None of these require tools or training — they're the simple habits of living with a system that's quietly doing its job.
- Glance at the manometer regularly. Different column heights = the fan is pulling suction and working. Equal heights = something's wrong. Pick a memorable moment — say, whenever you're down near the fan — and make the glance a habit.
- Confirm the fan is running. The fan is designed to run continuously and should never be switched off. If you find it off — flipped at a breaker, unplugged, or shut down after service — that's a problem to fix, not a power-saving feature.
- Ask your installer to show you how to check it. When the system goes in (or at your next service visit), have the C-NRPP-certified installer walk you through reading the manometer and confirming the fan is on. Two minutes at handover saves a lot of guesswork later.
- Ask about a warning device. Many systems can be fitted with an alarm or indicator that signals a fan failure. Health Canada recommends asking for a warning device at installation so you're alerted if the system stops working, rather than relying on remembering to look.
- Find the system label. A certified installer should leave a label on the system noting the activation date and the original suction (or flow) reading when it was commissioned. That reading is your baseline — it's what lets you notice later if the manometer has drifted from where it started.
Signs something's wrong
Any one of these is a reason to look closer and, if needed, call a professional:
- The manometer columns have equalized. Two columns now sitting level with each other point to lost suction — typically a stopped fan, a power problem, or a blockage or leak in the pipe.
- A previously-noted suction or flow reading has changed. If you (or the label) recorded where the gauge sat at activation and it's now noticeably different, the system's performance has shifted.
- The fan is silent, or it's older than about 10 years. Fans wear out; one near or past the ~5–10-year mark is on borrowed time, and silence where there used to be a faint hum is a flag. (Listening for the fan is a practical homeowner tip, not a Health Canada instruction — treat the manometer as your primary check.)
- After a power outage or a service visit, the fan didn't restart. Outages and maintenance are the classic moments a fan ends up off. Check that it came back on, and that the manometer shows suction again.
If you spot any of these, the manometer and the fan have told you what they can — the next step is a professional, and ultimately a test to confirm where your level actually stands.
The only way to know it's actually working: test
Here's the part homeowners most often miss. A manometer can read perfectly "fine" while your radon level is still elevated. The gauge confirms the fan is pulling suction; it does not confirm the result. If the system was under-sized, if part of the foundation isn't being reached, or if something about the home has changed, you can have good suction and a level that's still above the guideline. The gauge answers "is the fan working?" A test answers "is my home below 200 Bq/m³?" Both matter — but only the test tells you whether you're actually protected.
Health Canada's verification approach for a mitigated home has a clear sequence:
- A short-term test right after activation. Once the fan is on (started at least 24 hours later), a short-term test gives a quick confirmation that the system is working — before you've lived with it for a full season. This is one of the few jobs a short-term test is actually for.
- A long-term (about three-month) test the following heating season. This confirms the annual average is now below the guideline — the number that matters for your health. To avoid a conflict of interest, this confirmation test should ideally not be done by the company that installed the system.
- An initial long-term re-check within two years of activation.
- A long-term test every five years after that for as long as you own the system.
That cadence — short-term at activation, long-term the following heating season, a re-check within two years, then every five years — is the mitigated-home schedule. (If a re-check ever comes back at or above 200 Bq/m³, treat it like any high result: Health Canada recommends acting within one year, sooner the higher the level.) For the full retesting rhythm across all situations, see how often you should retest radon in Canada.
If your system isn't working
A mitigation system is mechanical, and like any mechanical thing it can be serviced and repaired. If the manometer has equalized, the fan is silent, or a confirmation test comes back high, here's the path:
- Contact a C-NRPP-certified mitigation professional. This is the same qualification you'd want for a new install — proper diagnostics matter for a repair too. Search the directory at c-nrpp.ca/find-a-professional. RadonTest.ca does not perform mitigation or recommend specific companies; our guide on how to choose a radon mitigator walks through the questions to ask.
- A failed fan is usually a straightforward fix. Fans last about 5 to 10 or more years, and replacement typically costs about $200–$300 — a modest repair that restores a system you've already invested in. A pro can also check that the rest of the system (sealing, suction points, venting) is still doing its job.
- Then confirm with a test. Once the system is running again, follow it with a long-term test to verify your level is back below the guideline — a working fan and a confirmed result are two separate boxes to tick.
If you want a refresher on how the whole system is meant to function — what the fan and pipe are actually doing under your home — see our companion guide, how radon mitigation works in Canada.
Frequently asked questions
How do I know my radon system is working? Two separate checks. First, the mechanical check: look at the U-tube manometer (different column heights = the fan is pulling suction) and confirm the fan is running continuously. Second — and this is the one that confirms you're protected — a radon test, because only a test shows whether your home is below 200 Bq/m³. A healthy gauge tells you the fan works; a test tells you whether the level is below 200 Bq/m³.
What does the manometer (U-tube) tell me? It shows the suction the system is pulling. When the two coloured liquid columns sit at different heights, the fan is moving air and the system is working. When they're equal (level with each other), the fan likely isn't working — a sign of a stopped fan, lost power, or a blockage.
Does the manometer measure radon? No. The manometer measures pressure/suction only — it tells you the fan is moving air, not how much radon is in your home. Health Canada frames this gauge as a fan/pressure indicator. To know your radon level, you need a radon test; the gauge can't tell you that.
How often should I retest after mitigation? A short-term test right after the system is activated, a long-term (about three-month) test the following heating season (ideally not by the installer), an initial long-term re-check within two years of activation, and a long-term test every five years afterward. See how often to retest radon in Canada.
How long do radon fans last? Typically about 5 to 10 or more years. When a fan wears out, replacement runs roughly $200–$300. The fan must run continuously and is never switched off; a silent fan, or one well past the 10-year mark, is worth checking.
My radon system's gauge looks fine — am I risk-free? The gauge looking fine means the fan is working — it does not mean your radon level is below the guideline. A system can pull good suction and still leave a home elevated if it's under-sized or conditions have changed. Don't call a home risk-free on the strength of the gauge; test to confirm you're below 200 Bq/m³.
What if the fan is off after a power outage? Switch your attention to the manometer once power's back: if the columns are equal, the fan hasn't restarted and the system isn't pulling suction. Many fans restart on their own, but not all do, and some need a reset. If it won't come back on, contact a C-NRPP-certified mitigation professional.
Should I have a warning device on my system? It's worth it. Health Canada recommends asking for a warning device at installation — an alarm or indicator that alerts you if the fan fails — so you're not relying on remembering to check the gauge. If your system doesn't have one, a certified pro can advise on adding one.
Confirm your system is doing its job
A working fan is the goal — but a long-term test is the proof. The manometer tells you the fan is moving air; a test tells you your home is actually below the Health Canada guideline. After mitigation, that confirmation is the step that lets you stop wondering.
Order your RadonTest.ca kit → — confirm your mitigation system is keeping you below the guideline with a long-term test: lab analysis by a C-NRPP-certified laboratory (with an all-in-Canada analysis option), tracked shipping both ways, and results delivered with clear Health Canada context.
Sources
- Health Canada — Radon: Reduction Guide for Canadians (U-tube manometer as fan/pressure indicator; continuous fan operation; warning-device recommendation; verification cadence — short-term at activation, long-term the following heating season ideally not by the installer, re-check within two years and every five years; fan lifespan 5–10+ years and replacement $200–$300), published Feb 2023, modified 2025-09-24. https://www.canada.ca/en/health-canada/services/environmental-workplace-health/reports-publications/radiation/radon-reduction-guide-canadians-health-canada.html
- Health Canada — Reducing radon levels in your home (mitigation systems and the continuously running fan; use of C-NRPP-certified professionals), modified 2025-10-09. https://radontest.ca/links/hc-mitigation-guide
- C-NRPP — Find a Professional (directory of certified measurement and mitigation professionals). https://c-nrpp.ca/find-a-professional/
- Take Action on Radon — Reducing radon (mitigation systems, fan operation, and verification testing for Canadians). https://takeactiononradon.ca/protect/reducing-radon/
The point that the manometer measures pressure/suction (fan operation) and not radon concentration is RadonTest.ca's plain-language clarification grounded in Health Canada's framing of the gauge as a fan/pressure indicator; listening for the fan is offered as a practical tip, not a Health Canada instruction. Lab analysis is performed independently by a C-NRPP-certified laboratory; results are reported against the Health Canada guideline of 200 Bq/m³. RadonTest.ca coordinates kit logistics and sample submission only — it does not interpret or modify lab results and does not provide medical, legal, or warranty advice. Information attributed to Health Canada, Take Action on Radon, and C-NRPP is summarized from the public sources listed above; confirm time-sensitive details with the responsible body.