Components of an ASD Radon Mitigation System
ASD (active soil depressurization) systems may consist of the following components:
The point where the radon mitigation system passes through the basement floor. Below the floor, the pipe connects to the suction pit.
Although you’ll never see it, the suction pit is an important component of the ASD system. In order to ensure that air is being sucked evenly from all areas beneath the foundation of your home, a suction pit is created by digging a hole in the soil and gravel beneath the floor of the basement. This method is an ingeniously simple concept that helps to increase the effectiveness of the radon mitigation system. The size of the pit is determined by the soil type, size of slab, and design of the mitigation system. Performing pre-installation diagnostics helps a C-NRPP professional to calculate the size of the pit required.
The pipe used to build an ASD system is Schedule 40 PVC pipe. The system can be installed using either 3” or 4” diameter pipe. This pipe is generally white or grey. This pipe is used because of its durability and its resistance to cracking. Maintaining a sealed system is important to ensure that radon doesn’t leak out and into the home.
The radon fan is the heart of the ASD system. Radon fans are specially designed to be air-tight, quiet and efficient. Radon fans are built to a higher standard than some other types of fans because the radon fan case must be completely sealed. As with all other sections of the radon mitigation system, there must be no air leakage between the fan and the home in order to avoid radon contamination of the home’s interior air. C-NRPP professionals will only use radon fans that have been approved and listed by C-NRPP.
Active radon mitigation systems have a system pressure gauge (often a U-Tube Manometer) that indicates the pressure in the piping system created by the radon fan. The initial pressure (indicated by the level of liquid in the tube) will be marked by the system installer. You should regularly check the gauge to ensure the system is operating properly. If the gauge indicates a substantial change (a 20% or more difference from the original marked pressure), or if it reads zero pressure (where the liquid in the tube is now level), your radon mitigation system may not be working properly and you should call for service. Sometimes, depending on where the system is installed, an electronic alarm is used. This alarm provides the homeowner with an audible alarm if the pressure of the system drops below an acceptable level. The electronic alarm is typically used when the fan is located in a location with limited accessibility, and viewing the System pressure gauge is difficult.
From the outside of your home, the only part of the radon mitigation system that will be visible is the exhaust pipe. This pipe usually exits the side of the house; typically from the area between the basement and main floor or above the roof level. In areas with considerable snowfall, the pipe must exit the home high enough from the ground so that it will not be blocked by snow in the winter. Your C-NRPP professional will also consider factors such as windows, decks, other air intake or discharge pipes in the house, neighbouring homes, and play areas when choosing the location for the exhaust pipe.
- Membranes – A plastic membrane may be used when a concrete basement floor slab is not present, or is not present in all areas of the building. In this case, a membrane should be used to provide a barrier seal between the building envelope (home) and the soil. The membrane can be added as part of a Radon Mitigation System called a Sub-Membrane Depressurization system.
- Sump Pit Cover: A tightly-fitted and sealed cover should be used over a sump or septic pit which is installed in a home. The cover must be properly fitted and sealed around the full area of the sump pit and sealed around all pipes and cords passing through the cover.
- Labels: the various components of a radon mitigation system should be properly labeled to ensure future occupants of the home are aware of the radon system.