How do I size a Radon Fan?

What radon fan is right for my home?

Radon fan sizing can be difficult for licensed mitigators, not to mention do-it-yourselfers.  When sizing a radon fan, there’s only one thing that matters: PRESSURE FIELD EXTENSION.  Pressure field extension simply means: how far am I drawing radioactive air from beneath my home?  It’s typically determined by taking specific measurements using a suction point and micro-manometer.  For the DIYer, these tools are cost-prohibitive.  If you want your radon mitigation system done right, always call a licensed, certified radon mitigator.

What am I getting myself into??

In order to estimate your fan size for yourself, you’ll need three things:

  1. Size of the building footprint (in square footage)
  2. Current radon level (long-term test, if possible)
  3. Building type
    • slab on grade
    • basement
    • walkout
    • tri-level or garden level
    • crawlspace, etc.

It is for this reason, that it’s impossible to size a radon fan before the building is completed and a radon level has been established.

With this information, PDS can help you size a fan by phone.

PDS’ phone estimations are just that: estimations.  Unfortunately, PDS does not take returns on DIY fan installs.  Take accurate measurements and be confident in your selection.  PDS is here to help.  The only folks with a guarantee are radon mitigation professionals performing contracted work.

Tips on fan sizing:

  • Use a floor bushing and dig a large suction pit (at least 15-20 gallons [3-4 “home depot” buckets] of dirt and debris).   Dirt augers are helpful tools for this job.
  • Always use a manometer.  PDS cannot help diagnose fan issues if we cannot calculate airflow and static pressure.
  • Be prepared to change fans or add a second system on the opposite end of the home.
    • Even mitigators with decades of experience sometimes come up short.  It’s not always as simple as adding a “bigger” fan.
  • Know what’s under your home:
    • request foundation plans from the original owner/home builder
    • 4″ gravel base or just dirt?
      • clay?  sand?  something else?
    • Were radon-ready new construction techniques used?  If so, what products were installed? (Home builder should have a record)
      • Typically, with properly designed RRNC homes, a low wattage, low-volume fan can be used like the Fantech Rn1 or the RadonAway RP145
  • How to Video: Understanding Fan Curves for performance calculations