Radon systems do not last forever. They have moving parts and failure points. Unfortunately, many homeowners are ignorant of these facts and many contractors are not educating the occupants of the home on what radon system maintenance is to be expected. This is why radon fan failure alarms are now required in states and municipalities that adopt consensus radon mitigation standards. The purpose of these alarms is to let the occupants know that the radon system may not be working.
Alarms are important
Never ignore a radon alarm. Yes they can be loud, yes they can be annoying, but they’re trying to get your attention. Just like the check engine light on your vehicle, a radon alarm is trying to tell you something. Read on to see what the alarm could be telling you and how to fix it.
How radon alarms work
Most radon alarms work in conjunction with a pressure gauge or manometer. When a radon system is installed, you’ll often see a U tube on the suction side of the system. This u tube is typically inside the home and somewhere easy to see by home occupants. It’s important to make note of the U tube reading because if it changes, you could be in trouble. A u tube is a lot like a speedometer on your car, it’s giving you important information, but it’s not giving you all the information. You can tell me that you’re driving 35 mph, but if you ask me if that’s safe, welp… I’m gonna need to know more, right? Are you in a school zone or the highway? Manometers are much the same way. Think of a radon alarm being like the lane assist feature on modern cars. It’s telling you to pay attention.
Most radon alarms will calibrate based on your initial radon mitigation system pressure. Let’s say you have a PDS 150 or KTA 150 radon fan and the U tube during alarm calibration is at 0.4″ of water column pressure. That is well within the operating range on that fan: so far so good. You’re moving about 200-250 cfm at that resistance; and hopefully all of that air is coming from your soil and not your house. A well designed system will only pull soil air. You test for radon and confirm that your radon system is functioning properly: your radon levels are low. Great! Now the alarm has calibrated and is ready to alert you if something changes.
Common Reasons a Radon Alarm Goes Off
Now let’s say our example system above starts beeping. Maybe you have the KTA 2.0 system with a built in radon alarm or maybe you have an aftermarket alarm like an Obar alert, RSA1 from RadonAway, or Fantech brand. The reasons for alarm will be the same, so let’s get into it.
Is the radon fan on?
First check the fan. Is the fan even on? This is far and away the most common reason an alarm will go off. Whoops, you had a breaker flip or a power failure. Oh no, someone unplugged the fan so they could plug in a power tool or xmas lights (why wasn’t it hardwired with a locking switch plate? hmmm). Or maybe someone cut the wire while working else where in the home? Or what if the fan was just plain old and it finally died?
These are all super duper common reasons a radon fan would be off. In the past, you wouldn’t hear anything. You wouldn’t see the radon levels rise because radon gas is invisible. You wouldn’t smell the radon like a natural gas leak; radon is odorless. You would simply live in ignorance until your next system inspection or radon test. GULP. That’s a scary thought. How many radon systems have dead fans and ignorant homeowners right now? I would guess thousands, maybe tens of thousands.
In this scenario, you simply turn the fan back on, the alarm stops its alerts; you perform a radon test and ensure everything is working. Phew, that was close!
What’s the U tube reading? Higher or lower?
High pressure
In this scenario, the radon fan is still on. You can hear it. However, your radon fan alarm is still beeping and flashing red. Now it’s time to inspect the U tube. You see the manometer is now at 1.7″ of W.C. pressure. You can’t remember what it was when they system was put in; however the certified radon pro followed standards and there is a placard right next to the U tube. You see that initial installation pressure was 0.4″ of suction. Wow that’s a big increase. There is a lot more resistance in your system. That’s like going from two thousand RPMs on your car to redlining at seven thousand. Something is definitely wrong.
Now check your system: is there a clog in the pipe? Often times, after power failures, radon systems can get clogged with leaves or debris from trees and critters.
Has it rained or snowed a lot recently? Is your sump pump on? Precipitation is the number one cause of spikes in radon system pressure. Just last week a homeowner called with a pesky, “annoying” radon alarm. After troubleshooting we found standing water inside their crawlspace. Radon fans cannot pull soil gas through water. Their system was effectively broken. On top of that they had water in their house! That will cause mold and other indoor air quality issues. It turns out a gutter got clogged and sent water back into the house–and the radon system found the problem before it became a much bigger issue! Hooray!
Low pressure
What if the U tube reading dropped to zero? Time to scroll back up. Your fan is turned off.
What if it didn’t go all the way to zero but maybe went down to 0.2″ of pressure? Well that means the system is now moving close to 300 CFM. That’s good right? More air is better—get all that radon out, right? It depends. Where is the air coming from? Usually if the system’s pressure drops significantly it’s a sign of a broken system. Imagine you’re drinking a milkshake and the straw gets a hole in it. Are you gonna be able to finish your milkshake?
Ripped crawlspace barrier or loose PVC are the two biggest culprits when it comes to significant pressure drops. Another common culprit is a windstorm (read here). Inspect the system from top to bottom. Use a smoke bottle if you have to. Be sure that there are not significant leaks. Check the radon fan couplers. Make any system repairs and you hope to see the manometer reading get back to normal. Always perform a radon test after system repairs to be sure they’re working correctly
Conclusion
Radon alarms are important. Yes they’re annoying when they go off at 2 a.m.., but we want them to get your attention. Radon is serious stuff and you need to be sure you’re not exposed to high levels—especially when you paid for a mitigation system.
Always assume the alarm is working correctly and work to find the problem. Most radon fan failure alarms work based on the pressure in the system. Understanding your initial installation pressure is key to understanding if your pressure increased or decreased significantly, which can then inform your inspection and repair decisions.
We hope this article helped you find your mitigation problem. If not, shoot us an email or give us a call!
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