Replacement Radon Fans, an Overview

replacement radon fans, ensure space between fan and wall
Ensuring space between fan and wall.

A Little Bit About Radon Fans

Radon Fans function as the heart of an active radon mitigation system. An active radon mitigation system is one that is powered by a radon fan, or one that uses some other sort of powered ventilation device, such as an air exchange ventilator or fresh air circulation fan as an integral aspect of the radon mitigation process. A passive radon mitigation system is one that does not have a fan.

Typically a radon fan is connected to 3 or 4 inch PVC vent pipes. It sucks air from below the basement or first floor of a building, from a hole that’s drilled through the concrete floor. The radon laden air is sucked up from below the floor, past the fan and pushed up and out the termination point of the radon vent pipe. The radon gas is sucked and pulled along with other air and soil gases including a lot of moisture that is also trapped in the soil beneath the building.

The primary technical requirements for a radon fan is that is rated for continuous use and can withstand high moisture conditions. The typical radon fan is basically an inline ventilation fan. There are well over 100 various types of radon replacement fans and models of radon fans produced by several manufacturers, that greatly vary in cost, size, shape, power curves, air flow characteristics, etc.

Replacing a radon fan, AMG Force, a box style radon fan, very powerful, made in USA by Festa Radon Fans
AMG Force, a very powerful fan

The average service life of the most radon fans is about 10 to 11 years, as reported by manufacturers in the USA. Most of the top radon fans are warrantied by the manufacturer for 5 years. Radon fans are quite durable since they are designed to run 24/7 year after year. I’ve replaced several radon fans that were in continuous service for well above 20 years. These longer service life spans, here in central New York, are achieved by fans installed in attics or heated spaces, and not on the exterior of the home, where cold weather conditions greatly shorten the life of radon fans.

For the most part, radon replacement fans are pretty efficient. On average the most common radon fans use about 65 to 75 watts. That roughly equals an electricity cost about $50 to $80 a year in a year. Some of the more powerful radon fans like the AMG Force pictured above, manufactured by Festa Radon Technologies, can use around 300 watts, costing around $200 a year or more to operate. In recent years there has been a trend in new highly and more powerful, DC low voltage radon fans. Some have twice or better the performance at a fraction of the energy usage, but they can be double or more the cost. These highly efficient low voltage DC radon fans can certainly be worth the extra cost especially in the long term, paying for themselves in energy cost savings.

Radon fans can also do a very good job of reducing indoor moisture. I like to point out this side benefit of many radon mitigation systems. Most basements, here in central new york anyways, have high humidity if not outright damp or wet. Concrete basement floors and concrete slabs on grade are like giant sponges that often absorb ground moisture, wicking it up through capillary action and release it into the indoor air, or even form puddles or damp spots on the floor. An average radon fan can easily pull up to several gallons a day of moisture or more from below the slab.

Case in point: I installed a radon mitigation system in a home as a condition for the sale of the home. It had a fully finished, basement level apartment. For many years the homeowner, living in the basement apartment, emptied his dehumidifier about 10 or 12 times every week, almost like clock work. He monitored the dehumidifier that ran almost continuously and dumped it out as needed once or twice every day. I returned about a week after the radon mitigation job to pick up a radon test and found the homeowner quite perplexed. He was wondering how this radon system could affect the operation of his dehumidifier. He explained that he had only dumped it once, the day after the system was installed, and kept checking it for a malfunction, since it had not filled up in nearly a week. The dehumidifier had only kicked on a few brief times and reservoir was nearly empty. I explained to him how much moisture a radon system could potentially remove. He said if he had know, he would of installed the radon mitigation system years ago for that benefit alone!

Consider the cost of running a radon fan verses a dehumidifier: An average radon fan running continuously costs about $65 a year and has the potential to remove several gallons or more a day of moisture from below the floor; Helping to keep the soil dry, reducing the moisture contact with the bottom of the concrete; Potentially as in the account above working better than a dehumidifier and you don’t have to empty it. Compare that to a single standard size dehumidifier designed to take up 70 pints of moisture from the air per day will cost about $350 a year. Multiply that times two or three as I have seen many homes with multiple dehumidifiers in the basements – all running. The cost of a radon mitigation system can in some cases, be offset in one or two years, in the energy savings alone, verses the cost of humidity / moisture reduction over multiple dehumidifiers and will do a better job of it.

Troubleshooting Radon Fans

Proper diagnostics help to properly size replacement radon fan
U-tube Manometer is a pressure gauge. When liquid is high on one side it indicates the fan is working.

Troubleshooting Radon Fans and Reading The Manometer: Radon fans work by moving along the radon laden air as the fan blades spin, then typically, after many years when the motor bearings seize up, they die. But there are some audible signs of old age that forwarn the need for radon replacement fans.

Noisy Radon Fans: As a radon fan ages beyond it’s productive service life, the motor bearings begin to wear out at an exponential rate, pending some other damage or defect to the fan. As the bearings begin to exponentially wear, they can become quite loud, ranging from annoying loud, to your neighbors calling the authorities to file a complaint, loud. Sometimes the loud bearing noise will come and go for short or long periods of time up to several months or even over a year, then can come back with a vengeance. The bearing noise coming and going seems to be associated with cold and warm temperatures. At any rate, when you hear a loud bearing noise coming from the radon fan, it’s telling you its on its last leg and you should plan on replacement.

U-tube Manometer – installed on the PVC vent pipe usually in the basement or occasionally in the garage. The manometer is a pressure gauge and serves as a visual indicator to let you know the radon system fan is operating. The proper operation of a radon fan is indicated by the Manometer Gauge, the “U” shaped tube with red or blue colored liquid in it. There should be a sticker next to the manomenter that explains how to read it. When the fan is properly working, the colored liquid is pulled higher on one side than the other, caused from suction inside the pipe pulling through the small vinyl tube going into one side of the “U” shaped tube.

Radon Mitigation Data Sticker: The sticker also states that if the colored liquid on both sides of the “U” are even, it indicates the system (fan) is not working and you should check the power source or call for service. See the accompanying pictures for reference. If the radon system installation followed the EPA or similar standards of practice, the sticker should include the contractors contact phone number to assist in questions or help in diagnosing problems.

When the manometer liquid is level on both sides, it indicates the fan is turned off or not working.

Orphan Radon Mitigation Systems: Unfortunately I have found many radon systems have no stickers, or stickers left blank, usually on purpose. Their installers not wanting to be contacted for any warranty or service work. It’s also common to find when there is a number, the company is no longer in business. In our Syracuse area of central New York, radon contractors come and go quite frequently. Most radon mitigation systems in this area are installed by contractors who do it as a part time side job, and do not want to be bothered with warranty or service work, hence, leaving the sticker blank. I refer to these as orphan systems.

Improperly Sized Radon Fans: I get quite a few calls, dozens a year, where a home has a operating radon mitigation system, but the radon level tested high. This is usually in the process of selling the home. In about half or more of these cases, I find the radon fan is undersized or not powerful enough to properly reduce the radon and replacement with the right fan reduces the radon sufficiently. At other times, in addition to changing out to a larger more powerful fan, other work is also required, such as additional suction point or balancing fresh air ventilation.

Radon Fan Wiring Problems. This is another issue that comes up sometimes. If the fan is not working, you need to ensure there is a good power source for the radon fan to operate 24/7. This may require evaluation by a qualified electrician. Sometimes there can be a short, caused from a loose wire or other issue that cuts off power to the fan. I have found radon fans that were hard wired to a switched circuit. An example of a radon fan being improperly wired is when it is wired into the basement light circuit. When the basement lights are turned off at the switch at the top of the stairs, it turns off the radon fan. The home owners never realize it because the light is turned on when they are in the basement and the radon manometer indicates the fan and system are working, only to be turned off again when the lights are turned off.

Gurgling From Groundwater. Most years I get one or more calls from people telling me there radon fan is making a gurgling noise at the suction point, usually in a basement floor. This is almost always due to high water table following a recent heavy prolonged rainfall or snow melting. If the water level in the ground rises up to the the bottom of the basement floor, to where it comes close to or in contact with the concrete the suction from the fan begins to lap the water up into the pipe, which can make a loud gurgling noise. This is usually the case when there is not good drainage under the floor, no sump pump or poorly operating sump pump. This is usually a temporary condition the will go away after a couple of day or in some cases a couple of weeks or so when the water table recedes to its normal level.

Obstructions In The Radon Fan. Sometimes things can get into the radon vent pipe. I have seen various things that fall or fly down down an uncovered radon vent pipe and land on the fan motor or get stuck in the blades. Depending on the object if small it may get chopped up and you never notice. Sometimes the object can block the fan blades from turning which will usually cause the fan motor to hum as it tries to turn the blades. Sometimes it can partially lodge in the spinning blades causing them to be out of balance that results in varying degrees of vibration and related noise from the vibration. Sometimes the fan is ruined and needs replacement, other times the item can be removed and the fan works fine.

Replacing a radon fan with a dead animal in it
Dead squirrel obstructing radon fan

Some of the things I’ve seen that got into radon vent pipes, landing on the fan are birds. Birds and critters typically will not enter a radon fan if it is blowing out a significant amount of air as most fans do. Some people turn off their radon systems when they go on vacation, which invites critters to investigate. I’ve see more than one bird nest build right on top of the radon fan in such a case. Other things I’ve found causing problems obstructing radon fans are, dead birds, dead squirrels, and sticks that fell from overhead branches.

Critter Covers. As you might surmise, some type of a screened cover would tend to keep most every type of thing out of the radon vent pipe. That is true. Most mitigation contractors offer some type of critter cover as an option for an added cost of about $20 to $50. The added cost, in addition to the fact that screened vent covers can sometimes greatly restrict the air flow and reduce the radon system efficiency are reasons they are usually not installed as part of a standard system. If your system has very low air flow however a screened cover is a good investment to prevent critter problems.

The location of a radon fan can vary greatly. Often people call me to replace or diagnose a noisy or failed radon fan and they don’t even know where the fan is located. Most radon fans in our area are located on an exterior wall of a home because that is the cheapest and easiest place to install them. A radon fan and vent pipe hanging on the side of a house is not really a thing of beauty, so they are usually relegated to one side or the other, out of sight as much as possible. I must admit I have seen radon fans installed on the front walls of homes a few times, as if they want to show it off, strange. If there is any option at all, I recommend for the sake of resale value, the front wall of a home should be your last choice for location of a radon fan.

Some radon fans are located in attic spaces, very commonly a garage attic space or other attic above the house. Garage attics are usually fairly easy to access, some have pull down stairs. The same is true of some attics above the house, but many homes attics can be quite difficult to access. Some attics access scuttles opening in ceilings are sealed off, and not readily accessible to service the radon fan. I have had to access radon fans in attics where the ceiling access, usually in a closet, was sealed off and covered over with blown in fiberglass or cellulose insulation. Talk about a mess when the hatch is opened up. Once in the attic the radon fans might be a long ways from the opening and difficult to get to through the insulation or low roof clearance.

Sometimes radon fans are located inside the house basement. This is true in our area in many of the bigger expensive homes that had radon systems installed prior to 1994. The basement was a logical place to install the radon fan, and they vented them outside like a dryer vent. Then the EPA came out with a national standard for radon mitigation installation which did not allow for radon fan placement inside or below the living areas in homes. Canada followed the United States lead and also not allowing for radon fan placement inside or below the living areas in homes. This meant in most cases as in the US that the radon fans were mounted on the exterior of homes and the vent pipes routed up the walls to above the roof.

But in the cold winter weather of Canada these systems ran into all kinds of icing issues. The warm moist air pulled from the ground through the radon fan would condensate further up the vent pipe and in very cold weather would freeze and the vent pipes would become blocked off with ice. This ice blockage stopped the air flow the rendered the radon mitigation system useless until it thawed out, which could be days, weeks or months. The icing issues also shortened the life of the radon fans by over half.

After research and testing, Canada decided it was preferable to place radon fans inside the home and vent them near ground level like a dryer vent. In the Canadian governments health agency online booklet titled, Radon Reduction Guide for Canadians” they recommend installing the radon fan in the basement of the home and venting out like a dryer vent. In my personal opinion the US would be doing well to follow suit. The EPA radon mitigation standards were quickly put together and basically mimicked the plumbing vent code, which designed to vent sewer gas. Sewer gas is very different than radon gas and can be quite smelly. Radon gas is odorless and dissipates very quickly when released into the outdoor air.

Replacing Your Radon Fan

Replacing an old radon fan
We recommend hiring a pro for replacing and old radon fan. It might seem like an easy job, but there are safety concerns and other issues that should be considered.

Replacing an old radon fan is sometimes simple but can also be daunting. First of all, from my experience of having replaced hundreds of radon replacement fans in central New York, half or so of the existing radon fans in homes today are no longer being manufactured. The manufactures have either gone out of business or have upgraded their old fans with new, more efficient models or in some cases, cheaper to manufacture models. As mentioned above there are more than 100 different radon fans readily available from various outlets.

Replace your own radon fan or Hire a pro? This may be a good question to ask if you consider yourself to have decent handyman skills. But, I will list below some reasons why I recommend you hire a professional to replace your old radon fan.

  • First, electrical safety. Most radon fans I have come across are hardwired to some type of electrical circuit. This means, as likely this is the case, it is a job for a qualified electrician. When connecting and disconnecting electrical wiring there is the potential for electrocution safety hazard.
  • Second, lifting safety. Lifting heavy weight may be required which could potentially cause injury to you or others or damage to your house or the radon system. Just yesterday I changed out an exterior radon fan on a two story house that had a 4 inch, schedule 40 PVC pipe and fittings. The heavy vent pipe extended up past the 2nd story roof, weighing close to 100 pounds or more. I had to disconnect the vent from the fan and from the brackets on the wall and change out the tight fitting fan while holding up the pipe. Kind of a balancing act and feat of strength combined with over 30 years of contractor experience.
  • Third, ladder safety. Two story homes typically require a ladder to detach and attach the radon vent pipe. All ladder jobs are potentially dangerous. Of course you will need a suitable ladder and it may require the assistance of a second person.
  • Fourth, choosing the right fan. As mentioned earlier, there’s over 100 different radon fans to choose from. Many older radon fans are no longer in production. It’s important to properly size the replacement fan to your system. There are a couple of very popular, less expensive radon fan models that are installed on the majority of systems; However for many homes they are woefully underpowered. A more powerful fan, at the same price point would be a much better choice.
  • Fifth, better choices available. A lot of the older model fans have been replaced by more efficient fans and some of the better fans are less expensive than direct replacements by about half the cost.
  • Sixth, some radon fan choices are really bad. Some radon fans are little better than junk, specifically some of the ones not made in the United States.
  • Seventh, warranties. Some of the biggest radon fan companies (two in the top three) can be quite difficult when trying to process a warranty claim. So difficult in fact that I stopped selling their fans, years ago. Good luck if you have a warranty issue with one of their fans.
  • Eighth, other warranty issues. Speaking of warranties, many of the manufacturer warranty programs only apply to fans installed by radon professionals.
  • Ninth, deceptive advertising. Some fans are marketed as radon fans but are not suitable to be used as a radon fan. They are either not rated for long term continuous duty or they are not rated for the high moisture conditions needed for a radon fan. This is typically a problem when looking for a cheap radon fan solution online.
  • Tenth, understanding fan design power curves. Some fans marketed for radon use, may meet the duty requirements, but are not designed with the proper power curves (kind of like torque) needed to suck air from below a concrete floor. At first glance they might look good on paper, with a high rate of CFM (cubic feet per minute) – air flow, but that air flow drops to near zero once resistance is introduced. In other words they may work great as a window fan or circulating air in a greenhouse, but really suck (perform poorly) at suction power needed for radon mitigation.

I hope this has been helpful for your understanding of radon replacement fans. Click here for a link to my other website for more information on choosing the correct radon fan.