Radon Manometer Reading High

Radon mitigation systems are installed to reduce natural radioactive gas from coming up into your home or building.  After installation, often you will see a white PVC pipe coming up from the concrete in the lowest floor’s slab.  If the install was done correctly, this pipe should be hidden as much as possible in a mechanical room, storage room, or in a closet.

What is a Radon Manometer?

Have you ever noticed the clear curved tube with colored liquid at the bottom attached to the radon pipe?  That is called the manometer.  It displays the level of air suction inside of the radon system.  It is a very helpful part of the radon system to give installers important information about the system performance as well as give home owners’ a visual clue that their system’s fan is running.  The manometer does NOT read the radon levels, but only pipe air pressures.  The only way to know radon levels after installing a radon system is to perform a radon retest.

How to Read a Radon Manometer

When the radon system is turned on, you should see one side of the colored liquid positioned higher than the other side.  If both sides are even (the same height), then there is a problem.  The higher side colored liquid shows the suction amount inside of the system piping.  The larger the number next to the top of the colored liquid, the higher the suction is in the pipe.  Higher suction does NOT mean more airflow.  It is opposite of what you would think.  The lower the number means that there is more airflow inside of the pipe.

For example, a radon system with a Festa Maverick fan with a monometer reading of 1.5” of water column shows that there is about 40 cubic feet of air moving through the pipe per minute.  At 1.0” water column, that number jumps up to over 100 cubic feet of air!  If the manometer reads 2.1” with a Maverick fan, then there is high pressure inside of the system but no airflow moving.

Don’t worry too much about the airflow.  Each house is different and to fix the radon problem, every home needs different amount of suction force to move sufficient air.  We have seen some homes with very high radon get fixed with very high suction and only a little movement of air, and other systems where we were moving hundreds of cubic feet of air per minute to get the radon down low.  Your certified radon installer should be trained to determine the correct size of piping and radon fan for your house’s unique situation.

My Manometer is at Zero.  What Should I do?

First verify that there is a flexible tube is coming out of the top of the manometer and going into the pipe.  The tube can sometimes be under tension and pop out.

Second put your ear to the pipe.  Do you hear air flowing?  If you do not, the fan is off.  The most common reason why fans turn off is that a breaker or CFCI powering the fan has been tripped and needs to be reset.  Note that GFCI breakers can be anywhere in the house and even on the outside on a porch or patio.  If you have an external radon system, make sure it has not been switched off or unplugged.  If you still can’t turn the fan back on, call the radon mitigation company that installed the system for assistance.

My Manometer Reading Has Changed Since it Was Installed

Let’s start by making sure the manometer is still calibrated correctly.  Pull out the flexible tube from the white radon pipe.  The colored liquid should now be even across the manometer.  If the liquid is at zero, your manometer is calibrated correctly.  If colored liquid is high or low compared to zero, then it was likely bumped and you can easily slide the rigid curved manometer tubing up or down on its mount to re-zero the liquid level.

It is common for the manometer reading to vary throughout the year.  Any change less than 0.4” is nothing to worry about.  If your manometer reading changes more than 1.4”, make sure that it is calibrated to zero as described above.  If it still is either high or low, contact your radon mitigation installer for assistance.

Is there any Maintenance I Need to Perform on My Manometer?

Unless it gets bumped and needs to be recalibrated back to zero as described above, the only possible thing you might need to do at some point would be to refill the colored liquid inside the manometer due to evaporation.  You can purchase manometer refill liquid from amazon or you can simply use water with some food coloring in it.

For more information contact Utah Radon Services.