Where to Drill PFE Test Holes

Pressure Field Extension Testing (PFE) is a critical step in radon mitigation. It helps optimize radon system design, determine the ideal suction point placement, and select the right size radon fan. PFE testing helps ensure the radon mitigation system is designed and installed to effectively remove radon from the entire home, creating a safe and healthy environment.

Do you ever wonder where to drill PFE test holes? Test holes should be where the pressure field extension is expected to be the weakest.

Let’s examine where we placed test holes in a 1975 home without drain tile.

This sketch illustrates where we placed test holes in the basement. Now, let’s examine why we selected these locations.

PFE Test Hole Placement

In the basement, a center footing divides the house into thirds: to the front of the center footing (points 5 and 6), to the back of the center footing (points 1 and 2), and the crawl space area to the right (points 3 and 4).

This home has a split entry with a crawl space under the entryway. The plan is to put the primary suction point in the crawl space. We will place a couple of test holes in there to ensure we reach the far corners (3 and 4).

To the front of the center footing is a bedroom, which is furthest from the suction point. We will place a test hole in the bedroom’s back corner (6) and the front corner (5). This room has carpet, so we can lift the corner to drill a test hole. Once we are done, we will fill the holes and re-stretch the carpet.

The living room may have a center footing under the slab going all the way through, so we would also want a test hole there (2).

On the back side of the center footing is an office space. We will also place a test hole in the far corner of that room (1). That area has a tile floor, so we will drill a 1/4″ hole in the grout line instead of a normal 1/2″ hole.

Finding Baseline and Target Pressure

Once the test holes are drilled, we connect tubing to each hole and run it back to the micromanometers. From there, we record our baseline pressures, and then we will figure out our target pressure. Target pressure field extension is the pressure we want to see in all our test holes once the system is up and running.

Want to Learn More?

If you want to learn more about figuring out target pressure and what goes into engineering a radon mitigation system, check out our video course. In this course, we will cover test hole placement, baseline pressure, target pressure, using the 2″ pitot tube from Kansas State University, overcoming challenges, friction loss, pipe sizing, and fan selection. The course offers 2 hours of NRPP CE credit.

Are you looking for a mitigator in the Twin Cities, MN, area that uses PFE testing on every mitigation system? Contact us for an estimate.