Valves and Dampers - American Radon Mitigation

Valves and Dampers

There is no known safe level of radon exposure, so we aim to reduce radon levels as much as possible at American Radon Mitigation. However, you shouldn’t have to pay excessive operating costs to achieve that. This article discusses how to use valves and dampers to reduce system operating costs without sacrificing radon reduction. 


A mitigation system needs to create a vacuum under the entire house to lower radon levels effectively. We found that in many instances, a small radon fan such as the RP140, Spirit, or Rn1 was not strong enough to create adequate suction under every area of the house, which meant that we would not see optimal radon reduction. However, a larger fan such as the RP145, Maverick, or Rn2 was oversized. Highly powered fans cost more to run and pull more conditioned air from the home. In addition, the large fan could increase operating costs by a few hundred dollars a year.

One way to improve efficiency is by using an adjustable radon fan such as a Fantech EC fan.

Adjustable Radon Fan


Another method is using valves and dampers, which are especially helpful for systems with multiple suction points that do not need the same amount of suction in each location. For instance, we usually only need to draw 5 to 10 CFM from a crawl space, so we typically use 2-inch PVC with a 2-inch ball valve, which allows the fan to draw more air from other areas of the home that need more suction.

Valves and Dampers

To demonstrate the difference valves can make, we performed a test using a mock-up system with a RadonAway RP145 and a 4-inch gate valve.

Difference Valves can make

Difference Valves can make

The fan consumed about 65 watts with the valve wide open, which meant it would cost about $65 a year to operate the fan. The U-tube showed a static pressure of about 0.2 inches.

Pressure with valve open

When we closed the valve halfway, the U-tube went up to 1 inch of static pressure, and the fan dropped to about 50 watts.

Pressure with half open

We reached 1.9 inches of static pressure and 34 watts when the valve was nearly closed.

Pressure with nearly closed

One downside to gate valves is that, when nearly closed, they whistle.

Nearly closed valves whistle


In those instances, we use an adjustable damper like the one below.

Adjustable Damper

We would save approximately 30 watts by nearly closing the valve, which translates to about $30 a year to run the fan. That figure does not account for the conditioned air loss, which is usually the largest component of the system’s operating cost. We’ve seen instances where the system was over $1,000 a year to operate, accounting for the loss of conditioned air. Dialing in the system improves overall efficiency for significant savings over the life of the system.

If you are interested in lowering radon levels as much as possible while still keeping energy costs down, contact us to set up a free estimate within the Twin Cities MN Metro area.