When people get a radon mitigation estimate, the install price is the first thing they look at. The second question is almost always about the fan: what will it add to my power bill, how long will it last and what happens when it quits?
Good questions. The fan runs around the clock for years, so it is worth understanding.
What the radon fan does
An active radon mitigation system has three main parts: a sealed suction point under the slab or under a crawl space membrane, a pipe that runs to above the roofline and an in-line fan in that pipe. The fan creates steady suction beneath the foundation, pulling radon-laden soil gas out from under the house and venting it outdoors before it can get inside.
If the fan stops, the system mostly stops working. That is why the fan is the part to keep an eye on.
How much electricity a radon fan uses
Radon fans run continuously, 24 hours a day, every day. A commonly cited range for radon fan power draw is about 100 to 300 watts, though models vary, and the right fan for a given house depends on the soil, the foundation and how much suction the system needs.
Typical yearly cost
The commonly cited estimate for the electricity to run a radon fan is about $30 to $300 per year, and most homes land toward the lower end of that range. Where your home falls depends on:
- The fan model and its wattage
- How hard the fan has to work, which depends on the soil and the foundation
- Your electricity rate
How to estimate your own fan's cost
If you know your fan's wattage, which is printed on its label or listed in its manual, you can estimate the yearly cost yourself:
- Multiply the wattage by 24 hours and by 365 days.
- Divide by 1,000 to get kilowatt-hours (kWh) per year.
- Multiply by the per-kWh rate on your power bill.
When we design a system, we size the fan to the house so it pulls enough suction without using more power than it needs.
How long a radon fan lasts
Radon fans are commonly replaced every 5 to 10 years. Some last longer and some fail earlier. Things that affect fan life include:
- Running conditions. A fan working against a lot of resistance works harder.
- Moisture. Soil gas carries moisture, and condensation in the pipe is normal. A properly sloped pipe lets water drain back down rather than collecting in the fan.
- Heat and weather exposure. Fans are installed outdoors or in an attic, never in the living space, so they see real temperature swings.
- Installation. A fan mounted so it is not stressed by the pipe, with good seals, tends to have an easier life.
Since a fan replacement is a normal part of owning a radon system, it is worth budgeting for one within that 5 to 10 year window.
How to check your system: the manometer
Most radon systems have a manometer on the pipe, usually a small U-shaped tube with colored liquid. It shows whether the fan is creating suction.
- Liquid levels uneven: the fan is pulling suction. This is what you want to see.
- Liquid levels even: no suction. The fan may be off, failed or unplugged, or the pipe may be disconnected or blocked.
- A big change from the installed reading: something has changed. Many installers mark the original level, so compare against that mark.
Make a habit of glancing at it every so often, such as when you change your HVAC filter. It takes five seconds.
A working manometer means the fan is pulling suction. It does not tell you your radon level. The EPA recommends retesting after mitigation, and retesting periodically after that is a good idea too.
Radon fan noise
A properly installed radon fan should make a low, steady hum, if you notice it at all. Because fans go outside or in the attic and not inside the living space, most homeowners rarely hear them. Things that can make a system louder:
- A fan mounted near a bedroom window or against a wall that carries vibration
- Air rushing noise from pipe sizing or routing
- Water gurgling in the pipe, usually from condensation
- A bearing starting to wear out
A new grinding, rattling or squealing sound is worth checking out. It is often the first sign a fan is near the end of its life.
Signs your radon fan needs attention
- The manometer reads even or has moved a lot from its original mark
- The fan is silent when it used to hum, or noisier than it used to be
- A follow-up radon test comes back higher than your post-install result
- The fan is past the 5 to 10 year range and you have never had it checked
- Visible damage to the pipe, the fan housing or the electrical connection
Before assuming the fan is dead, check the simple things: the breaker, the outdoor disconnect switch if there is one and whether the pipe has come apart at a joint.
Fan quiet, noisy or reading wrong? We repair and replace radon fans on existing systems, including systems someone else installed. Fan replacement and repair are quoted on site. Get a free quote.
Replacing a radon fan
Fan replacement is usually a straightforward job. The old fan comes out, a properly sized replacement goes in, seals and connections are checked and the manometer is reset. It is also a good time to look at the rest of the system for cracked pipe, loose fittings or a torn crawl space membrane. Then a radon test confirms the system is still keeping levels down.
Because the right fan depends on the system, we quote fan replacement and system repair on site. See our radon system repair page for more.
The full cost of owning a radon system
Putting it together, here is what a typical system looks like over its life:
| Item | Typical range |
|---|---|
| Sub-slab depressurization (slab or basement) | $900–$2,500 |
| Crawl space sub-membrane system | $1,500–$3,500 |
| Combination foundation (crawl + slab/basement) | $2,200–$3,800 |
| Electricity to run the fan | about $30–$300 per year |
| Fan replacement / system repair | quoted on site, typically every 5–10 years for the fan |
All prices are estimates; your final price comes after an on-site look. For the install side, see our radon mitigation cost guide, our sub-slab depressurization page and our guide to radon in crawl space homes.
Frequently asked questions
How much electricity does a radon fan use?
Radon fans run 24 hours a day. A commonly cited range for their power draw is about 100 to 300 watts, depending on the model. The commonly cited yearly electricity cost is about $30 to $300, with most homes toward the lower end. Multiply your fan's wattage by 8,760 hours, divide by 1,000 and multiply by your rate to estimate yours.
How long does a radon fan last?
Radon fans are commonly replaced every 5 to 10 years. Moisture, heat, how hard the fan has to work and how it was installed all affect its life. Check the manometer on the pipe now and then; if the liquid levels are even or have moved a lot from the original mark, the fan may need attention.