Radon systems help to reduce the humidity levels in basements in addition to reducing the radon levels in homes. A typical radon system can cause a 4 to 10% reduction in the relative humidity in the basement of a house.
As you know, radon systems are put in place to prevent Radon gas from entering homes. But how does it help to reduce moisture levels in a house? Does this mean you don’t need a dehumidifier?
How does a radon system reduce moisture?
A radon system reduces humidity inside a house by creating a negative pressure zone between the basement and the soil underneath it. This causes the humid air inside the basement to move into the radon system and out of the house.
But not all radon systems reduce humidity, only active sub-slab depressurization systems reduce humidity.
Let me explain this in detail;
The secret to humidity reduction lies in the effect a radon system has on the pressure inside the basement of a house. As you know, due to the stack effect, the hot air in the basement moves upward, creating a negative pressure zone there. It is this negative pressure that draws in radon gas from the soil underneath it.
This negative pressure in the basement also draws in moisture from the soil and outside. This is the reason why the basements of homes are generally more humid than their other living areas.
You can reduce these moisture and radon levels by installing a fan-based active sub-slab depressurization radon system. This system uses a fan to suck out the air beneath the foundation of the basement. This creates a negative pressure zone between the basement and the soil below it.
This negative pressure zone draws in the moist air from the basement. This moist air is removed through the pipes of the mitigation system to the outside. This airflow from the basement to the radon system causes the less humid air from the outside to come in. This new air replaces the old humid air of the basement, thus lowering its overall humidity. This is how a radon mitigation system helps to reduce humidity.
Does a radon system reduce humidity in summers and winters?
Environmental Protection Agency ran an experiment in 2007 (Source) to study the effect of an active radon system in humidity reduction. According to the study, the humidity reduction by radon systems is most effective during winter months when the humidity of the outside air is low. During the summer months, radon mitigation systems didn’t show any significant reduction in humidity levels due to the high moisture content in the air outside.
But how does the effect of radon systems on indoor air humidity relates to outside air humidity?
As mentioned before, an active radon mitigation system like ASD (Active Soil Depressurization) causes outside air to come into the basement. As the humid air in the basement is replaced by this outside air, the humidity of the outside air matters. Since air humidity is higher in the summer months, the air drawn into the basement is also humid. This is why radon systems do not cause any significant reduction in humidity during the summer months. But they are more effective in the winter months since the relative humidity of the outside air is lower in those months.
How long does it take for a radon system to reduce moisture?
The duration for seeing the effect of a radon mitigation system on humidity can vary from a few weeks to months, depending on the size of the mitigation system and the basement’s size and design. The more powerful a system is, the faster it can dry the air. Mitigation systems also dry a smaller basement faster than a larger one. The duration also depends on the layout of the basement and the things in it. A simple basement with no furniture or obstructions will dry faster than a complex one.
How effective is a radon mitigation system in reducing humidity
During the winter months, a radon mitigation system can reduce 4 to 10% of moisture from the basement of a house. The mitigation systems used in EPA’s testing (of which I mentioned earlier) extracted 13 to 19 gallons of moisture per day during the testing months.
Using a full depressurization system that draws air from multiple sources is more effective in reducing moisture levels than using the same system but having a single inlet pipe.
A radon mitigation system also reduces the load on the dehumidifier in the basement of the house. However, a radon system cannot replace a dehumidifier, especially during summer when the humidity levels are higher.
Do radon systems help with mold?
Radon systems help reduce mold growth since they reduce the humidity levels inside the house’s basement. You will notice a significant reduction in mold growth and that musty smell in the basement a few weeks after installing a new radon mitigation system.
The reduction in indoor humidity levels can lower asthma cases, especially in children. As 21% of Asthma cases in the USA are attributed to dampness and mold exposure, I would say that a radon mitigation system is doing a good job. It will also improve the moisture-resistant properties of the concrete foundation and basement floor. These benefits are enough reason to install a fan-based ASD (Active Soil Depressurization) radon system at your house.
Can radon systems increase humidity?
A radon system can increase humidity during humid, summer months. This is because it replaces the air inside the house with the more moist air from the outside.
This is the reason why you shouldn’t get rid of your dehumidifier for a radon system. The primary function of radon systems is to reduce radon levels, not humidity. One has to use a dehumidifier to reduce moisture levels during the hot summer months.
Where does the water in the radon pipes go?
Since the radon mitigation system also sucks in the humid air in the basement, there will be condensations in its pipes. This condensed water is removed using a condensate bypass which will pass this water to the sump pump.
Here is how a condensate bypass work;