Can I reduce the radon fan noise?
Most likely, yes. This is a common question I get from people. There are several factors that can contribute to radon fan noise. We will take a look at each contributing factor.
Not all of the following factors apply to every situation, it is usually a combination. Over the years having installed hundreds of radon mitigation systems myself, I have learned some basic noise reducing procedures as well as some specialized methods for tough situations I will share with you.
An Installation NOTE:
After installing hundreds of radon mitigation systems for my clients, I have come to learn quickly most people do not like a noisy radon mitigation system. After the first couple of noise or vibration complaints, I gave particular consideration to noise reduction in the design and installation of the radon systems I installed.
It is much easier to to avoid noise and vibration during installation, verses after the system is installed. The small added cost or labor up front, is well worth it, compared to a noisy radon system or bothersome vibration felt throughout the home. This is also one of the differences between a good and not so good radon contractor.
Fan Motor Noise
Fan motor noise is primarily related to how powerful the fan is or the amount of wattage used by the fan motor. Often a larger fan is used than what is needed.
This type of noise can be reduce by the placement choice of the fan. Ideally installing the fan in a well insulated attic space greatly reduces or eliminates any noise heard inside the home.
If the fan is installed in an attic or garage the fan can be wrapped with fiberglass insulation. You can get fiberglass insulation with a vinyl or plastic cover on one or both sides, secure it with zip ties. Make sure to use a fan specifically designed or radon and the cool air flowing through fan will keep it from overheating even when wrapped with insulation.
Radon Fan Vibration
All radon fans will have at least a little vibration, that is helped by using rubber couplings at the top and bottom when mounting the fan. These rubber couplings also make it easy remove the fan for replacement.
However, many contractors use a hole saw the exact size of the radon vent pipe when they drill through a rim joist, beam, or wall sheathing to mount the radon fan on the exterior a home. This puts the radon vent pipe in direct contact with the framing of the home usually just a foot or so away from the fan. Even using rubber couplings much vibration is transferred to the structure and can be felt in the walls and floor.
Often I have seen where the radon fan itself is in direct contact with the siding or a framing component of the building. This vibration can produce a low pitch hum that can be heard (and felt) throughout adjoining rooms in the home.
Brackets and Hangers
This same vibration can also be transferred due to the way the vent pipe or fan is secured to the structure.
There are many different ways to secure, brace, or attach radon fans and vent pipes. There are PVC pipe clamps and J hooks, metal pipe hangers and brackets, and threaded rod steel hangers, steel strapping tape and vinyl strapping tape and various improvised or custom types also.
Air Flow Noise
If a radon fan is installed outside the building, it should not be audible inside unless there is a window close by, that is sometimes opened. This noise would be from both airflow and the fan. A lower wattage fan would be the best solution. If the noise transfer is through an open second floor window then it is likely to be the piping airflow noise and the exhaust noise. The exhaust piping could be switched to thicker walled PVC piping or even a muffler on the exhaust stack if aesthetics is not a concern.
PIPE THICKNESS: Radon PVC piping is either 1/8 inch walled schedule 20 also known as sewer and drain (S&D) or 1/4″ walled schedule 40 DVW or schedule 40 foamcore pipe. Using thicker walled pipe, especially the foamcore, will partially reduce airflow noise transmission.
SYSTEMS ROUTED THROUGH CLOSETS: If the house has a single floor section (ranch style) the system can be piped up through a closet to the attic. Avoid using a master bedroom closet. A hall closet is the best choice for minimal noise impact.
INSULATING THE PIPE: Piping that is routed through a space that needs to minimize airflow noise can be insulated for noise reduction. Sliding the next size larger flexible insulated duct over the pipe in the area that needs to have quieter piping can be very effective. Using closed cell foam or thicker walled pipe is less effective.
CRAWL SPACE MEMBRANES: If the home has a dirt floor crawl space the airflow noise from a sub-membrane suction system can sometimes be audible in the living area above the crawl space. Open face fiberglass insulation can be placed on top of the membrane or in the joist cavities above the suction location to dampen the noise. The smaller the pipe size drawing air from under the membrane the quieter the air flow noise. To reduce sub-membrane noise, downsize the pipe under the membrane to a 2″ pipe which can move up to 50 cfm or a 1.5 inch pipe that can move up to 35 cfm of air.
ROUTING NEW CONSTRUCTION PIPING: The air moving through a radon pipe has enough noise to be carried through drywall. Try to not route new construction passive radon pipes through walls adjacent to a bedroom, especially the master bedroom. Builders rarely think about this detail. If you can hear air flow noise through the drywall your only partial solution is installing a lower wattage fan in the attic. If it is really bothersome to the owner the system may need to be re-piped up the outside of the home.
EXHAUST MUFFLERS: Companies that supply radon products manufacturer different style air flow mufflers. Some of the mufflers restrict the airflow at higher airflow speeds. This would only affect high airflow systems. Their effectiveness for noise reduction also varies. In general a muffler will not reduce the airflow noise coming from the piping or the fan noise itself. The mufflers will however lower the exhaust noise if they are placed near the exhaust port. The actual noise reduction is moderate but the sound pitch is lowered which makes the noise less offensive. System exhaust noise is usually only bothersome if the exhaust is at the first floor roof and the exhaust pipe is visible from a location that is frequently occupied. A 2nd floor window that looks at a radon exhaust pipe on the garage roof or an exhaust out of a ranch roof that is visible from a rear deck would be good canidates for a muffler. The best muffler noise reduction is with the muffler installed on the end of the exhaust pipe with no chimney cap so that air flow is straight up. We have installed the muffler on the exhaust port on the roof for maximum noise reduction even though it looks a bit out of place.
Your Radon Mitigation Contractor
If your radon mitigation contractor is concerned about customer satisfaction he should be willing to make a good effort to help reduce the noise in your system. It is not unreasonable to ask for him to do so.
Need More Help?
Leave a comment below and I will give it my best shot. If you think it would help, you can send me a couple of pictures of the problem using the Contact Us page.
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