Keep your family safe from effects of radon
November is Radon Action Month, and recently I wrote about key things everyone should know about the gas. This week I want to discuss the importance of the radon fan when it comes to sub-depressurization mitigation techniques.
Radon gas is created when the uranium in our soil and rocks decays. Radon gas outside is safe but if it gets inside your home, it can be harmful in concentrated amounts, possibly leading to lung cancer. It is actually the leading environmental cause of lung cancer after smoking.
Radon fans are an integral part of the radon mitigation system that pulls air from the soil and vents it outdoors through a pipe that ends above the roof's edge. Drawing air from below the slab creates a negative pressure and stops radon from entering your home through the foundation.
A radon mitigation system must be leak-free to prevent radon contamination. That's why you'll find Canadian-national Radon Professional Program professionals only using C-nrpp-approved radon fans.
Not all radon mitigation systems have fans. For example a passive radon system doesn't include a radon fan. However, these systems are marginally effective and frequently fail at keeping radon below safe levels.
The radon mitigation fan is an essential element of the mitigation system. There are three main types of radon fans: low
suction, moderate suction and high suction.
When there is a drain tile or four to six inches (10-15 cm) of gravel under your property, radon reduction systems often use low suction and airflow fans. These fans are the quietest because of the low draw level.
Moderate suction fans are used for medium to large homes with gravel or drain tile under the concrete slab. They can move a lot of air without much suction, suggesting that the slab has numerous cracks and holes or that the material under your house is porous. Homes with drain tile and concrete block walls tend to leak the most.
Typically, high-suction fans are used with tight soils like clay and sand. These fans require four inch (10 cm) piping and often numerous slab penetrations to pull sufficient air. They are noisy, and will need a noise suppressor due to the high suction rate.
Today, there are energy efficient radon fans that come with EC motors. These fans can be dialed down to consume as little
as one watt of energy in certain applications, making them a great investment in the long run for the energy-conscious homeowner.
A backdraft in equipment, such as your water heater, could result from a radon system that draws too much air from within your house, resulting in carbon monoxide and causing severe risk to your family. To stop the radon system from sucking conditioned air out of your home, block openings to the earth wherever practical. A radon professional will seal all the cracks and holes in your slab during installation, preventing these backdrafts from occurring.
All radon sub-depressurization techniques use the same radon vent system, and the radon fan must run continually. Radon gas will be extracted from the soil and expelled to the home's exterior when connected to a subsystem and PVC piping.
Make sure that the discharge is above the building's eaves, at least 10 feet (3 metres) away from building openings, and less than two feet (0.6 metres) below the discharge so the gases cannot re-enter the residence. The system can be routed either inside or outside the home.
The system should be installed by a C-NRPP certified professional who will determine the correct fan based on the airflow tests performed. The fan will typically be placed in your basement or attic. Any vent pipe running through non-conditioned air space must be insulated to prevent freezing.
Fans may last five years or longer (manufacturer guarantees rarely go beyond five years). They will cost approximately $300 to $600 for a replacement and people with a radon mitigation system should retest every two to three years or have a continuous radon monitor in their home.
Your system will also have a U-tube manometer which will monitor and alert you when the fan malfunctions; however, more systems installed by radon professionals now have alarms that sound when the airflow in the vent pipe stops.
Your best bet to avoid radon problems is to keep radon out of the home in the first place. Subslab ventilation and membrane products are available for new construction homes and should be part of the national building code (currently only coded in parts of Ontario).
If you have high radon levels, several mitigation methods and products can help you reduce the radon levels in your home. Ask your builder about how they are addressing radon and request a radon mitigation system be installed. Get your older home tested and take the necessary steps to keep your family safe and healthy.